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Chemistry > Topic 1 - Key Concepts In Chemistry > Flashcards

Topic 1 - Key Concepts In Chemistry Flashcards

1
Q

Titanium and iron are examples of transition metals.
Figure 6 shows the % abundance of each isotope in a sample of titanium. Calculate the RAM of titanium in this sample. (2)

Ti-46 = 8
Ti-47 = 7
Ti-48 = 75
Ti-49 = 6
Ti-50 = 4

A

Ti-46 = 8
Ti-47 = 7
Ti-48 = 75
Ti-49 = 6
Ti-50 = 4
= 100 (1)

46 x 8 = 368
47 x 7 = 329
48 x 75 = 3600
49 x 6 = 294
50 x 4 = 200
Total = 4791 (1)

4791/100 = 47.91 (1)

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2
Q

The atomic number of magnesium is 12.
Magnesium exists as 3 isotopes: magnesium-24, magnesium-25 and magnesium-26.
Describe, by referring to the numbers of subatomic particles, the differences between 1 atom of each of these isotopes. (2)

A

Mg-24, Mg-25 & Mg-26 have 12, 13 & 14 neutrons (1)
Mg-25 & Mg-26 have 1 & 2 more neutrons than Mg-24. (1)

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3
Q

Explain, in terms of subatomic particles, what is meant by the term isotopes. (2)

A

Atoms with the same number of protons (1)
But different number of neutrons (1)

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4
Q

Element E has an atomic number of 5.
In a sample of E there are two isotopes. One isotope has a mass number of 10 and the other
isotope has a mass number of 11. Select an option. (1)

All atoms of element E in this sample contain:
5 protons
5 neutrons
6 protons
6 neutrons

A

5 protons

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5
Q

Calcium has an atomic number of 20 and a mass number of 40.
Which row of the table shows the number of protons and number of neutrons in this atom of calcium?

No. of protons - No. of neutrons
20 - 20
40 - 20
20 - 60
60 - 20

A

20 protons - 20 neutrons

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6
Q

Figure 8 shows the arrangement of electrons in an atom of calcium. Explain, using the information in Figure 8, in which period of the periodic table calcium
can be found. (2)

2, 8, 8, 2

A

Period 4 (1)
As it has 4 electrons (1)

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7
Q

Chlorine has an atomic number of 17.
The nucleus of an atom is made up of protons and neutrons.
Atoms of chlorine contain 17 protons. Figure 4 shows some information about a proton, a neutron and an electron.
RAM Relative charge
Proton. 1 +1
Neutron 1 0
Electron Almost 0 -1

Explain, using the information in Figure 3 and Figure 4, why atoms of chlorine have no overall charge. (2)

A

Same number of protons & electrons (1)
So charges cancel/balance each other (1)

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8
Q

Atoms of chlorine-37 have a mass number of 37.
Calculate the number of neutrons in atoms of chlorine-37. (1)

A

37 - 17 = 20

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9
Q

The scientist John Dalton lived over 200 years ago.
John Dalton suggested an early model of atoms.
When Dalton first described atoms he said that
 all elements are made of atoms
 atoms are not formed of any smaller particles
 all atoms of the same element are identical.
Give 2 differences between Dalton’s model of atoms and today’s model of atoms. (2)

A

In modern model:
Atoms are formed of sub-atomic particles (1)
Atoms have a nucleus (1)
Atoms contain protons (1)
Atoms contain neutrons (1)
Atoms contain (shells of) electrons (1)
Atoms of same element can have different numbers of neutrons (isotopes exist) (1)

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10
Q

A sample of silicon contains isotopes.
State, in terms of subatomic particles, how atoms of these isotopes are the same. (1)

A

Same number of protons

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11
Q

This sample of silicon contains three isotopes.
92% of the atoms are silicon-28
5% of the atoms are silicon-29
3% of the atoms are silicon-30
Calculate the relative atomic mass of silicon in this sample. (2)

A

28x92 + 29x5 + 30x3 = 2811 (1)
2811/100 = 28.11 (1)

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12
Q

A carbon atom contains 6 electrons, 7 neutrons and 6 protons.
State the mass number of this atom. (1) ……………..…..
Give its electronic configuration. (1) ………………

A

13
2,4

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13
Q

An atom of aluminium has an atomic mass of 27.
Aluminium has an atomic number of 13.
State the number of electrons, neutrons and protons in this atom. (3)

A

Electrons = 13
Neutrons = 14
Protons = 13

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14
Q

Figure 4 shows the atomic number and mass number of two isotopes of argon.
Describe the structure of an atom of argon-38 and of an atom of argon-40. (3)

Isotope Atomic number Mass number
Argon-38 18 38
Argon-40 18 40

A

Both have 18 electrons/2,8,8 8n shells/orbits (1)
Both have 18 protons in their nucleus (1)
Argon-38 has 20 neutrons and Argon-40 has 22 neutrons (in the nucleus) (1)

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15
Q

A sample of magnesium contains
79% of magnesium-24 atoms
10% of magnesium-25 atoms
11% of magnesium-26 atoms.
In most calculations the RAM of Mg used is 24.
Use this information to explain why, in this sample, magnesium has a RAM of 24.3 (6)

A

RAM of magnesium is 24.3 due to:
The existence of more than 1 isotope
Accurate relative mass is calculated using weighted mean
Magnesium-25 and Magnesium-26 are both heavier isotopes than magnesium-24
Magnesium has the highest %
Therefore the RAM is closer to 24 than 25 or 26

Calculation of RAM:
Consider 100 atom sample
In the the given sample 79 atoms have a mass of 24
In the the given sample 10 atoms have a mass of 25
In the the given sample 11 atoms have a mass of 26
Total mass of 100 atoms = 75
75/100 = RAM = 0.75

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16
Q

An ion of element X can be represented as
125^ X ^2-
This ion of element X has 54 electrons.
Calculate the number of protons and the number of neutrons in this ion. (2)

A

Number of protons = 54-2 = 52 (1)
Number of neutrons = 125-52 = 73 (1)

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17
Q

An atom of potassium has atomic number 19 and mass number 39.
Give the electronic configuration of this potassium atom. (1) ……………………………………
This potassium atom forms the ion K+
Which row shows the number of protons and the number of neutrons in this potassium ion, K+? (1)

Number of protons. Number of neutrons
19. 19
19. 20
20. 19
20. 20

A

19 protons - 20 neutrons

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18
Q

Magnesium has an atomic number of 12.
Which line in the table shows the correct numbers of protons, neutrons and electrons in a positively charged magnesium ion? (1)

Protons Neutrons Electrons
10 12 12
10 12 10
12 10 12
12 12 10

A

Mg2+
12 protons - 12 neutrons - 10 electrons

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19
Q

An aluminium atom has the atomic number 13 and the mass number 27.
Which row shows the numbers of subatomic particles present in an aluminium ion, Al3+?

Protons Neutrons Electrons
13 14 13
13 14 10
14 13 10
14 13 17

A

13 protons - 14 neutrons - 10 electrons

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20
Q

In 1871, the Russian chemist Dmitri Mendeleev produced the first version of the periodic
table.
Describe how Mendeleev arranged the elements in this 1st version of the periodic table and why the elements are arranged differently in the modern periodic table. (4)

A

Using the properties of the known elements & their compounds at the time (1)
leaving gaps for elements/predicting existence and properties of elements yet to be discovered/newly discovered elements have been added (1)
In order of increasing RAM (1)
In modern periodic table, elements arranged in order of increasing atomic number (1)
Mendeleev thought he’d arranged the elements in the order of increasing RAM, but this wasn’t always true due to the relative abundance of some of the pairs of isotopes (1)

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21
Q

Explain why chlorine belongs to group 7 of the periodic table. (2)

A

Seven electrons (1)
In outer shell (1)

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22
Q

Gallium is in the same group in the periodic table as aluminium and in the same period in the periodic table as bromine.
State in which group and period of the periodic table gallium can be found. (2)

A

Group = 3
Period = 4

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23
Q

Gallium had not been discovered when Mendeleev created his 1st periodic table.
Figure 9 shows some properties of gallium that Mendeleev predicted and some of the actual properties of gallium.
Describe how Mendeleev predicted these properties of gallium. (2)

Property Predicted property Actual property
RAM. About 68. 70
density. About 6. 5.9
Melting point. Lower than 40’C. 29.8’C
Density of oxide. About 5.5. 5.9

A

Compared them to the elements in the same group/period (1)
And used the trend/pattern going down the group/across a period (1)

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24
Q

State how you know that calcium is a metal from its position in the periodic table. (1)

A

In group 2

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25
Q

In the 19th century, Mendeleev arranged the elements known at the time to form his periodic table.
Mendeleev’s periodic table is different from the modern periodic table.
State one difference between Mendeleev’s periodic table and the modern periodic table. (1)

A

It was arranged by increasing relative mass.

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26
Q

Element X has an atomic number of 18. It’s in period 3, group 0.
State the electronic configuration of an atom of element X. (1)

A

2, 8, 8

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27
Q

Complete the following sentences.
The name given to group 7 in the periodic table is ………………… (1)
The name given to group 0 in the periodic table is …………………. (1)

A

Halogens (1)
Noble gases (1)

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28
Q

Explain how the electronic configuration of an atom of potassium is related to its position in
the periodic table. (2)

A

Number of electrons in its outer shell gives the group number. (1)
Number of electron shells gives the period number. (1)

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29
Q

Potassium and caesium are in the same group of the periodic table.
Explain, in terms of electrons, why potassium and caesium are in the same group. (2)

A

Same number of electrons (1)
in their outer shell. (1)

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30
Q

Give the symbol of an element in group 1. (Other than Li, Na or K) (1)

A

Rb/Cs/Fr

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31
Q

Describe the test to show that a gas is oxygen. (2)

A

A glowing splint (1)
Relights (1)

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32
Q

Potassium oxide is ionic.
Write the electronic configurations for the ions in potassium oxide, K2O. (2)

A

Potassium ion = 2, 8, 8
Oxide ion = 2, 8

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33
Q

Which element is liquid at room temperature and pressure? (1)
fluorine
chlorine
bromine
iodine

A

Bromine

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34
Q

Which element is dark-grey in colour at room temperature and pressure? (1)
fluorine
chlorine
bromine
iodine

A

Iodide

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35
Q

Mendeleev produced one of the earliest periodic tables.
State why he could not include any of the noble gases in his periodic table. (1)

A

None of them were known/discovered yet

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36
Q

The electronic configuration of a metal is 2, 8, 3.
Which group and period of the periodic table does it belong to? (2)

A

Group 3 (1)
Period 3 (1)

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37
Q

Waste water may contain phosphate ions, .
Aluminium ions react with phosphate ions to form aluminium phosphate.
Complete the ionic equation for the formation of aluminium phosphate in this reaction. (2)

A

Al^3+ + PO4^3- → AlPO4

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38
Q

Figure 6 shows some properties of three substances, A, B and C.
Deduce, using the information in Figure 6, the structure and bonding of substances A, B and C, explaining their properties in terms of their structure and bonding. (6)

A. MP=1180. Poor ability to conduct electricity when solid, good when molten
B. MP=1538. Good ability to conduct electricity when solid, good when molten
C. Mp=115. Poor ability to conduct electricity when solid, poor when molten

A

Substance A:
Giant ionic structure
(High melting point) strong electrostatic attractions between ions
Due to a lot of energy required to overcome strong forces
(Electrical conductivity) in solid ions, strongly attracted in lattice ions can move, so poor conduct when solid
When molten, ions are are free to move, so good conductor when molten

Substance B:
Metallic structure
(High melting point) strong attraction between metal ions and delocalised electrons
Due to a lot of energy required to overcome strong forces between particles in solid
(Electrical conductivity) in solid delocalised electrons
Free to move throughout metallic lattice, so good conductor when solid
Delocalised electrons and ions free to move when molten, so good conductor when molten

Substance C:
Covalent simple molecular
(Low melting point) weak intermolecular forces/attractions between molecules
Little energy need to separate molecules, so low melting point
(Electrical conductivity) in solid and when molten no delocalised electrons or ions to carry charge, so poor conductor

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39
Q

The method used to extract a metal from its ore depends on the position of the metal in the
reactivity series.
(i) One step in the extraction of titanium metal involves the displacement reaction between
titanium chloride, TiCl4, and magnesium.
TiCl4 + 2Mg → Ti + 2MgCl2
This equation can be simplified as
Ti4+ + 2Mg → Ti + 2Mg2+
Explain why this displacement reaction can be described as a redox reaction. (3)

A

Both oxidation and reduction take place (1)
Magnesium atoms lose electrons (oxidised) (1)
Titanium ions gain electrons (reduced) (1)

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40
Q

The formula of the sulfate ion is SO4^2−
Which of the following is the formula of titanium sulfate containing the Ti^4+ ion? (1)

TiSO4
Ti2SO4
Ti(SO4)2
Ti2S2O8

A

Ti(SO4)2

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41
Q

Ammonia reacts with nitric acid to form ammonium nitrate.
Complete the word equation for this reaction. (1)

A

Ammonia + nitric acid → ammonium nitrate

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42
Q

Explain why farmers spread ammonium nitrate on their fields. (2)

A

Acts as a fertiliser (1)
To increase crop yield (1)

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43
Q

An ammonium ion has the formula NH4^+
A nitrate ion has the formula NO3^–
Which of the following is the formula for ammonium nitrate? (1)

(NH)4NO3
(NH4NO)3
NH4NO3
(NHNO)12

A

Nh4NO3

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44
Q

Magnesium carbonate has the formula MgCO3.
Magnesium carbonate contains Mg2+ and CO32− ions.
The atomic number of magnesium is 12.
What is the electronic configuration of the Mg2+ ion? (1)

A

2, 8

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45
Q

Explain why solid magnesium carbonate cannot conduct electricity but solid magnesium
can. (3)

A

Ions in magnesium can’t move/held in a lattice/held together by strong electrostatic forces (1)
Magnesium contains delocalised electrons (1)
Electrons in magnesium can move (1)

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46
Q

What is the formula of the sulfate ion? (1)

A

SO4^2-

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47
Q

Sodium sulfate, Na2SO4, is an ionic solid.
Which of these is most likely to be a property of solid sodium sulfate? (1)

good conductor of electricity
high melting point
low boiling point
malleable

A

High melting point

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48
Q

Explain, in terms of electrons, how a sodium atom, Na, forms a sodium ion, Na+ (2)

A

Loses electrons (1)
Loses 1 electron (1)

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49
Q

Describe the test to show that a gas is hydrogen.

A

Apply a lit splint (1)
You should hear a squeaky pop (1)

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50
Q

Nickel is a metal.
Explain how the structure of a nickel atom, Ni, changes when it forms a nickel ion, Ni2+ (2)

A

Loses electrons (1)
Loses 2 electrons (1)

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51
Q

Potassium carbonate reacts with dilute sulfuric acid to form potassium sulfate.
Potassium sulfate contains potassium ions, K+, and sulfate ions, SO4^2-.
Write the formula of potassium sulfate.

A

K2SO4

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52
Q

The ions present in sodium sulfate are:
Sodium = Na+
Sulfate = SO4^2-
Write the formula of sodium sulfate using this information.

A

Na2SO4

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53
Q

The solid used in an experiment contained only NH4^+ ions and NOs^- ions.
Give the formula and the name of the solid. (2)

A

NH4NO3 (1)
Ammonium nitrate (1)

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54
Q

A solid ionic compound is dissolved in water to form a solution.
Describe a simple experiment to show that charged particles are present in this solution

A

Insert electrodes (into aqueous solution) (1)
Connect to electricity supply/powerpack/battery/cell (2)
Bulb lights/ammeter shows current/electrolyte decomposes (1)

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55
Q

Two compounds of barium are barium sulfide and barium chloride.
The sodium chloride solution is electrolysed.
State why sodium chloride solution, rather than solid sodium chloride, must be used in this experiment. (1)

A

So that the ions can move

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56
Q

Two compounds of barium are barium sulfide and barium chloride.
The sodium chloride solution is electrolysed.
The formulae of the ions present in the sodium chloride solution are: Na+ Cl- H+ OH-
Which ions would be attracted to the anode? (1)

A

OH-
Cl-

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57
Q

Molten lead bromide can be electrolysed to form molten lead and bromine gas.
Explain how a student could modify the apparatus (glass beaker, electricity supply, sodium chloride solution and electrodes) to carry out this electrolysis. (2)

A

Use a crucible/metal container (instead of beaker) (1)
Which will not break/melt (when heated strongly) (1)
OR
Add a Bunsen burner (under the container) (1)
Because heat is needed to melt the lead bromide/make the lead bromide a liquid (1)

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58
Q

Sodium chloride is an ionic compound, containing sodium ions, Na+, and chloride ions, Cl–.
Figure 15 shows the electronic configuration of sodium and chlorine.
Explain how sodium and chlorine atoms form the ions in sodium chloride and how the ions are arranged in the solid sodium chloride. (6)

                     Electronic configuration  Sodium.              2.8.1 Chlorine.             2.8.7
A

Sodium atoms lose electrons
Each sodium atom loses 1 electron
To obtain the electronic configuration 2.8
Which is that of sodium ions
Electrons transfer to chlorine atoms
Chlorine atoms gain electrons
Each chlorine atom gains 1 electron
To obtain electronic configuration 2.8.8
Which is that of chloride ions
Sodium ions attract chloride ions
Because of opposite charges
Ions pack close together
Ratio of ions 1:1
Ions arranged in lattice
Giant ionic structure

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59
Q

Figure 12 shows the melting points of two substances, A and B, and the abilities of the
substances to conduct an electric current when solid and when molten.
One of the substances has an ionic structure and one has a simple molecular, covalent structure.
Explain, in terms of bonding and the forces between the particles, the relative melting points
and abilities to conduct the electric current of substances A and B.

                                       Ability to conduct electricity Substance         MP          When solid       When molten A                         35              No                       No B                         801            No                       Yes
A

Simple molecular substances:
Have low melting point because=
Molecules have weak forces (intermolecular forces) between molecules. Little energy needed to overcome these intermolecular forces.
Don’t conduct electricity when solid/molten because=
Don’t contain any ions/charged particles/delocalised electrons. Therefore substance A is covalent.

Ionic substances:
Have high melting points because=
Strong electrostatic forces of attraction between ions. A lot of heat energy is needed to overcome these forces between ions.
Conduct electricity when molten because=
Ions are present and are free to move.
Don’t conduct electricity when solid because=
Ions are present and aren’t free to move. Therefore, substance B is ionic.

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60
Q

Calcium nitrate and calcium carbonate are both ionic compounds.
Calcium nitrate mixed with water behaves as an electrolyte.
Calcium carbonate mixed with water does not behave as an electrolyte.
Explain, in terms of solubility and movement of ions, this difference in behaviour. (2)

A

Calcium nitrate is soluble, calcium carbonate is insoluble (1)
So ions are free to move in solution/not free in solid (1)

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61
Q

A student used some equipment to investigate whether electricity can pass through solid ammonium chloride and through ammonium chloride solution.
If an electrical current flows in the circuit, the lamp will light up.
Figure 4 shows the results of the investigation.
Explain the results of the investigation. (3)

Substance Lamp
Solid ammonium chloride Didn’t light up
Ammonium chloride solution Lit up brightly

A

Ammonium chloride solution conducts electricity and solid ammonium chloride doesn’t conduct electricity (1)
Ammonium chloride contains ions (1)
In solution ions can move/in solid ions can’t move (1)

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62
Q

Potassium chloride has a melting point of 770°C.
Explain why potassium chloride has a high melting point. (2)

A

Ionic/lattice structure/strong electrostatic forces of attraction (1)
So needs a large amount of heat/energy to overcome these ionic forces (1)

63
Q

Sodium reacts with chlorine to form sodium chloride.
The electronic configuration of the sodium atom is 2.8.1 and the electronic configuration of the chlorine atom is 2.8.7.
Give the electronic configurations of the ions formed. (2)

A

Na^+ = 2.8
Cl^- = 2.8.8

64
Q

A molecule of methane can be represented in several different ways as shown in Figure 7.
These representations have been labelled A–E to assist you in your answer.
Describe what information can be obtained from each representation including the limitations of these representations of methane. (6)
A= molecular formula
B= dot and cross diagram
C= structural formula
D= ball and stick diagram
E= space filling (3d)

A

They show methane contains carbon and hydrogen
Structure A only shows the ratio of C:H as 1:4
Structure A gives no information about bonding in molecule/shape of molecule
Dot and cross diagram B shows the covalent bonding between the Carbon and Hydrogen atoms
Single bonds shown in B, C & D
Inner shell not involved in bonding
Structure B doesn’t show the 3d positions of atoms
Single lines used to show single covalent bonds in structure C
Only a 2d representation and not positions in space
Ball and stick model, D, shows position in space/3d arrangement
Atoms not actual connected by the sticks
Structure E space filling structure model shows 3d arrangement of atoms
E shows approximate relative sizes occupied by separate atoms
No information about type of bond between atoms atoms in structure E

65
Q

Diamond and graphite are both forms of carbon.
In both substances, the carbon atoms are held together by covalent bonds.
Describe what is meant by a covalent bond. (2)

A

Shared electrons (1)
A shared pair of electrons (1)

66
Q

Diamond has a very high melting point.
Explain why the melting point of diamond is very high. (2)

A

Diamond has a giant covalent structure/strong covalent bonds (1)
A large amount of heat energy is needed to break the lattice/bonds (1)

67
Q

Many fertilisers are produced using ammonia.
Ammonia is produced on an industrial scale from the reaction of nitrogen with hydrogen.
The equation for the reaction is
nitrogen + hydrogen ↔ ammonia
State the name of this industrial process. (1)
……………………..
State the meaning of the ↔ symbol in the equation. (1) ……………………..

A

Haber process
Reaction is reversible

68
Q

Sodium reacts with hydrochloric acid to form sodium chloride and hydrogen.
Write the word equation for this reaction. (2)

A

Sodium + hydrochloride acid (1) → sodium chloride + hydrogen (1)

69
Q

Give the formula for ammonia (1)

A

NH3

70
Q

Diamond has a very high melting point.
Explain why the melting point of diamond is very high. (2)

A

Diamond is a giant covalent structure/has strong covalent bonds (1)
A large amount of heat energy is needed to break these bonds/the lattice (1)

71
Q

Which ions are attracted to the negative electrode (cathode) during the electrolysis.

H+ OH- Na+ SO4^2-

A

H+ Na+

72
Q

State why it is important that the electrodes are inert in electrolysis. (1)

A

So that they don’t react with the electrolyte

73
Q

Explain, in terms of its structure, how graphite conducts electricity. (2)

A

Delocalised electrons (1)
Can move between the layers (1)

74
Q

Figure 12 shows the melting points of two substances, A and B, and the abilities of the substances to conduct an electric current when solid and when molten.
One of the substances has an ionic structure and one has a simple molecular, covalent structure.
Explain, in terms of bonding and the forces between the particles, the relative melting points and abilities to conduct the electric current of substances A and B. (6)

Substance A: MP=35 Doesn’t conduct electricity when solid or molten
Substance B:MP=801 Doesn’t conduct electricity when solid, conducts when molten

A

Simple molecular substances:
Have low melting points because there are weak intermolecular forces between molecules. So little energy is required to overcome/break these forces.
Don’t conduct when solid or molten, because they don’t contain any charged particles/ions/delocalised electrons. Substance A is covalent.

Ionic substances:
Have high melting points because there are strong forces of electrostatic attraction between ions. A lot of energy is required to overcome/break these forces. They conduct when molten as ions are free to move. But don’t conduct when solid, as ions aren’t free to move. Substance B is ionic.

75
Q

2 compounds of barium are barium sulfide and barium chloride.
The sodium chloride solution is electrolysed.
State why sodium chloride solution, rather than solid sodium chloride, must be used in this experiment. (1)

A

So that the ions can move

76
Q

Molten lead bromide can be electrolysed to form molten lead and bromine gas.
Explain how a student could modify the apparatus shown in Figure 8 to carry out this electrolysis. (2)

Glass beaker, electricity supply, sodium chloride solution and 2 electrodes

A

Use a crucible/metal container (instead of a beaker) (1)
Which will not break/melt (when heated strongly) (1)

77
Q

Calcium nitrate and calcium carbonate are both ionic compounds.
Calcium nitrate mixed with water behaves as an electrolyte. Calcium carbonate mixed with water doesn’t behave as an electrolyte.
Explain, in terms of solubility and movement of ions, this difference in behaviour. (2)

A

Calcium nitrate is soluble, calcium carbonate is insoluble. (1)
So ions are free to move in a solution/not free to move in a solid. (1)

78
Q

Explain why graphene will be a good conductor of an electric current. (3)

A

Carbon has four outer shell electrons (1)
Each carbon forms 3 bonds/3 electrons used in bond with other carbon atoms (1)
1 electron is free to move (delocalised) (1)

79
Q

Potassium chloride has a melting point of 770°C.
Explain why potassium chloride has a high melting point. (2)

A

Ionic lattice structure/strong ionic bonds (1)
Needs a large amount of energy to break/overcome these forces (1)

80
Q

Diamond has a giant covalent structure.
State one property of diamond that is the result of its giant covalent structure. (1)

A

High melting/boiling point/insoluble in water/doesn’t conduct electricity (1)

81
Q

Explain, in terms of electrons, how a sodium atom, Na, forms a sodium ion, Na+ (2)

A

Loses electrons (1)
Loses 1 electron (1)

82
Q

Substance X is a gas at room temperature.
It is a simple molecular, covalent substance.
Which row of the table shows the properties that substance X is most likely to have? (1)

BP= -6 Low solubility in water
BP= 600 High solubility in water
BP= -6 High solubility in water
BP= 600 Low solubility in water

A

BP= -6 Low solubility in water

83
Q

Gallium, Ga, is in the same group of the modern periodic table as aluminium.
The formula of aluminium oxide is Al2O3.
Predict the formula of gallium oxide. (1)

A

Ga2O3

84
Q

Gallium oxide has a very high melting point.
Gallium oxide does not conduct electricity when solid but does conduct electricity when molten.
What type of substance is gallium oxide? (1)

A

Ionic

85
Q

Magnesium carbonate has the formula MgCO3.
Magnesium carbonate contains Mg2+ and CO32-
The atomic number of magnesium is 12.
What is the electronic configuration of the Mg2+ ion? (1)

A

2.8

86
Q

Explain why solid magnesium carbonate cannot conduct electricity but solid magnesium can. (3)

A

Ions in magnesium carbonate can’t move/held together in a lattice (1)
Magnesium contains delocalised/free electrons (1)
Electrons in magnesium can flow/move (1)

87
Q

State two characteristic properties of metals. (2)

A

High melting point (1)
High boiling point (1)
Malleable (1)
Conducts electricity (1)
Conducts heat (1)
High density (1)
Shiny (1)
Ductile (1)
Strong (1)
Sonorous (1)

88
Q

Covalent substances can be simple molecular covalent or giant covalent.
Ammonia is a simple molecular, covalent substance.
Which is the most likely set of properties for ammonia? (1)

MP= 1713 BP= 2950 doesn’t conduct electricity in liquid form
MP= -78 BP= -33 doesn’t conduct electricity in liquid form
MP= -39 BP= 357 conducts electricity in liquid form
MP= 801 BP= 1413 conducts electricity in liquid form

A

MP= -78 BP= -33 doesn’t conduct electricity in liquid form

89
Q

Ammonia, NH3, is made by reacting nitrogen with hydrogen.
Write the balanced equation for this reaction. (2)

A

N2 + 3H2 → 2NH3 (2)

90
Q

Gold can be hammered into shape.
State the name of this property. (1)

A

Malleable

91
Q

Gold alloys can be used to repair teeth.
One reason that gold alloys are used is that they can be hammered into shape.
Give one other reason why gold alloys are used to repair teeth. (1)

A

Doesn’t corrode/insoluble/unreactive/inert/non-toxic/hard

92
Q

Alloy steels are made when iron is alloyed with other transition metals such as cobalt and chromium.
Metals have high melting points.
Explain, in terms of their structure and bonding, why metals have high melting points. (2)

A

Metal ions are surrounded by delocalised electrons (1)
Strong forces of attraction between ions and delocalised electrons (1)
A lot of energy needed to break these bonds (1)

93
Q

Covalent substances can be simple molecular covalent or giant covalent.
Consider these three substances:
Diamond, graphene and a fullerene

Explain, in terms of their structures and bonding, their relative melting points, strengths and abilities to conduct electricity. (6)

A

In all structures the carbon atoms bonded by single strong covalent bonds - shared pair of electrons
In diamond
In diamond, each carbon atom bonded to 4 others
Diamond & graphene have a giant covalent structure/lattice
Fullerene has a molecular structure
In graphene & fullerene each carbon atom is joined to 3 others
Many bonds need to be broken to melt diamond & graphene - need lots of energy, therefore, high melting points
Weak forces between molecules in fullerene - less energy needed to separate molecules, so has lowest melting point and low strength
Diamond and graphene have lots of strong covalent bonds, so both are very strong materials.
Diamond doesn’t conduct, as there are no free electrons
In graphene & fullerene, each carbon atom has 1 free electron, hence delocalised electrons.
Graphene conducts electricity
Fullerenes only conducts electricity across the surface of the molecule, no/little movement of electrons between molecules, so fullerene is poor conductor of electricity

94
Q

Bromine is a liquid at room temperature and vaporises readily.
Bromine has a simple molecular structure.
Which row of the table shows the most likely melting and boiling points of bromine? (1)

MP= -70 BP= -6.3
MP= -17 BP= 6.3
MP= -7 BP= 63
MP= 17 BP= 630

A

MP= -7 BP= 63

95
Q

Calcium chloride can be prepared by the reaction of calcium with chlorine gas.
Figure 9 shows some properties of calcium, chlorine and calcium chloride.
Explain, in terms of bonding and structure, why the properties of the product, calcium chloride, are different from the properties of the reactants, calcium and chlorine. (6)

Calcium: high MP good conductor of electricity when solid & molten
Chlorine: low MP bad conductor of electricity when solid & molten
Calcium chloride: high MP bad conductor of electricity when solid but good when molten

A

STRUCTURE:
calcium chloride is an ionic compound with lattice of positive and negative ions
calcium is a metal and so has a metallic structure of delocalised electrons
chlorine is a simple molecular covalent compound

MELTING POINT:
there are strong electrostatic forces of attraction/ionic bonds between the ions in calcium chloride
a large amount of heat energy is required to break these electrostatic forces - so calcium chloride has a high melting point
strong electrostatic forces between ions and delocalised electrons in calcium - a large amount of heat energy is required to break these electrostatic forces (so calcium has a high melting point)
chlorine has weak forces of attraction between its molecules - only need a small amount of energy to break down (so chlorine has a low melting point)

CONDUCTIVITY WHEN SOLID:
ions are fixed in a lattice and so can’t move (therefore calcium chloride cannot conduct a current) delocalised electrons in metallic structure can move to carry a current (so calcium can conduct a current) there are no delocalised electrons/ions/charged particles in chlorine molecules and (so chlorine cannot conduct a current)

CONDUCTIVITY WHEN MOLTEN:
however, when molten ions are free to move (and therefore molten calcium chloride can conduct a current)
delocalised electrons in metallic structure can move to carry a current (so calcium can conduct a current) there are no delocalised electrons/ions/charged particles in chlorine molecules and (so chlorine cannot conduct a current)

96
Q

A solid ionic compound is dissolved in water to form a solution.
Describe a simple experiment to show that charged particles are present in this solution. (3)

A

Insert electrodes (into aqueous solution) (1)
Connect to electrical supply (1)
Bulb lights/ammeter shows current/electrolyte decomposes (1)

97
Q

Molten zinc chloride is an electrolyte.
Which row shows the products formed at the anode and at the cathode when molten zinc chloride is electrolysed? (1)

Product at anode= oxygen/chlorine
Product at cathode= zinc/hydrogen

A

Product at anode= chlorine
Product at cathode= zinc

98
Q

Which of the following is the reason why molten zinc chloride is an electrolyte? (1)

it contains molecules that can move
it has a giant structure
it contains delocalised electrons
it contains ions that can move

A

it contains ions that can move

99
Q

Sodium chloride is an ionic compound, containing sodium ions, Na+, and chloride ions, Cl–
Figure 15 shows the electronic configuration of sodium and chlorine.
Explain how sodium & chlorine atoms form the ions in sodium chloride and how the ions are arranged in the solid sodium chloride. (6)

Sodium = 2.8.1
Chlorine = 2.8.7

A

sodium atoms lose electrons
each sodium atom loses one electron
to obtain electronic configuration 2.8 which is that of sodium ions,
Na-electrons transfer to chlorine atoms
chlorine atoms gain electrons
each chlorine atom gains one electron to obtain electronic configuration 2.8.8 which is that of chloride ions, Cl-
sodium ions attract chloride ions because of opposite charges
ions pack close together ratio of ions 1:1
ions arranged in lattice - giant (ionic) (structure)

100
Q

A student used the equipment in Figure 3 to investigate whether electricity can pass through
solid ammonium chloride and through ammonium chloride solution.
If an electrical current flows in the circuit, the lamp will light up.
Figure 4 shows the results of the investigation.
Explain the results of the investigation. (3)

Solid ammonium chloride= lamp didn’t light up
Ammonium chloride solution = lamp lit up brightly

A

Ammonium chloride solution conducts electricity and solid ammonium chloride doesn’t (1)
Ammonium chloride contains ions (1)
Ions can move in solution but not in solid (1)

101
Q

Carbon dioxide is a simple molecular, covalent compound.
It has a low boiling point of –78.5 °C.
Explain why carbon dioxide has a low boiling point. (2)

A

Weak intermolecular forces between molecules (1)
Little heat energy required to break these forces (1)

102
Q

A titration is to be carried out to find the concentration of a solution of sodium hydroxide.
The sodium hydroxide solution is titrated with dilute sulfuric acid.
The available apparatus includes a burette, a pipette, a funnel, a conical flask and an
indicator.
State one safety precaution that must be taken when using sodium hydroxide solution
and dilute sulfuric acid. (1)

A

Wear gloves to prevent contact with skin/safety (1)
Spectacles to proven contact with eyes (1)

103
Q

The sodium hydroxide solution is made by dissolving 4.3 g of sodium hydroxide in water and making the solution up to 250 cm3 with water.
Calculate the concentration of the solution in g dm−3
(2)

A

100cm^3 = 4.3 x 1000/250 (1)
1dm^3 = 17.1 (1)

104
Q

Write the balanced equation for the reaction of dilute sulfuric acid, H2SO4, with sodium hydroxide. (2)

A

2NaOH + H2SO4 → Na2SO4 + 2H2O (2)

105
Q

The results of titrations to determine how much of an acid is required to neutralise a given volume of an alkaline solution are shown.
Two of the titrations in Figure 14 should not be used to calculate the mean volume of acid required.
Identify each titration and give a reason why it should not be used in the calculation of the mean. (2)

Acid used in titration 1: 27
Acid used in titration 2: 25.30
Acid used in titration 3: 25.20
Acid used in titration 4: 25.80

A

Titration 1 shouldn’t be used because the burette reading isn’t precise/accurate enough. (1)
Titration 4 shouldn’t be used because the volume of acid used isn’t concordant with the other two. (1)

106
Q

The pylons are made of steel. The steel is mainly iron.
Iron is extracted from iron oxide, Fe2O3.
In the production of the iron, carbon dioxide is also produced.
Calculate the relative formula mass of carbon dioxide, CO2. (2)
(relative atomic masses: C = 12, O = 16)

A

12 + (16x2) (1)
= 44 (1)

107
Q

The equation for the reaction used in the extraction of iron is: 2Fe2O3 + 3C → 4Fe + 3CO2
Calculate the maximum mass of iron that could be obtained from 640 tonnes of iron oxide, Fe2O3. (3)
(relative atomic mass: Fe = 56; relative formula mass Fe2O3 = 160)

A

160 tonnes of iron oxide → 112 tonnes of iron (1)
640 tonnes of iron oxide → 112 x 640/160 tonnes of iron (1)
= 448 tonnes (1)

108
Q

An atom of copper has an atomic number of 29 and a mass number of 63.
Complete the table to show the numbers of protons, neutrons and electrons in this atom of copper. (2)

Number of protons =
Number of neutrons =
Number of electrons =

A

Number of protons = 29
Number of neutrons = 34
Number of electrons = 29

109
Q

Copper is in period 4 of the periodic table.
State what information this gives about the number of shells that contain electrons, in a copper atom. (1)

A

Copper has 4 shells of electrons

110
Q

Copper nitrate contains copper ions, Cu2+, and nitrate ions, NO3−
Describe, in terms of electrons, how a copper atom, Cu, becomes a copper ion, Cu2+ (2)

A

It loses (1)
2 electrons (1)

111
Q

Write the formula for copper nitrate. (1)

A

Cu(NO3)2

112
Q

The symbols for some atoms are given below:
Ca Cl K N O Ne
choose the atom in group 2 of the periodic table (1)
……………………………………
an atom that readily forms an ion with a charge of 2– (1)
……………………………………

A

Ca (1)
O (1)

113
Q

The formula of aluminium nitrate is Al(NO3)3
State the total number of atoms in the formula Al(NO3)3 (1)

A

13

114
Q

What is the most likely formula of aluminium nitride?
(1)

Al(NO3)2
AlNO3
AlNO2
AlN

A

AlN

115
Q

Chlorine has an atomic number of 17.
Chlorine-35 and chlorine-37 are two isotopes of chlorine.
Complete the table to show the numbers of protons, neutrons and electrons in each of the isotopes. (2)

number of protons in chlorine-35 =
number of neutrons in chlorine-35 =
number of electrons in chlorine-35 =
number of protons in chlorine-37 =
number of neutrons in chlorine-37 =
number of electrons in chlorine-37 =

A

number of protons in chlorine-35 = 17
number of neutrons in chlorine-35 = 18
number of electrons in chlorine-35 = 17
number of protons in chlorine-37 = 17
number of neutrons in chlorine-37 = 20
number of electrons in chlorine-37 = 17

116
Q

A normal sample of chlorine contains only chlorine-35 and chlorine-37 atoms.
Explain why the relative atomic mass of chlorine is 35.5 (2)

A

Average mass of isotopes present (1)
More chlorine-35 than chlorine-37 (1)

117
Q

Compare a use of diamond with a use of graphite, explaining each use in terms of the bonding and structure. (6)

A

DIAMOND:
Uses and properties- In cutting tools/engraving, Drill bit, Jewellery, Attractive/lustrous, High melting point
Explanations- giant molecular/covalent, each carbon atom bonds to 4 other carbon atoms, 3 dimensional structure, lots of energy needed to break it, in order to be broken many bonds would need to be broken.

GRAPHITE:
Uses and properties- to make electrodes, a lubricant, sporting equipment, pencils/drawing, conducts electricity, soft
Explanations- giant molecular/covalent, each carbon atom bonds to 3 other carbon atoms so has a free electron, delocalised electrons move to carry current, layers of carbon atoms, weak forces/bonds between layers, so layers can slide over each other.

118
Q

State what is meant by the atomic number (1)

A

Number of protons

119
Q

The atomic number of boron is 5.
Boron exists as two isotopes boron-10 and boron-11.
Use this information to explain why boron-10 and boron-11 are isotopes. (2)

A

Atoms of both isotopes have the same number of protons; 5 (1)
The atoms contain a different number of neutrons (1)

120
Q

Explain what is meant by the term relative atomic mass. (2)

A

Average mass of atoms of an element (1)
Mass of carbon-12 atom taken as 12 (1)

121
Q

Sodium chloride is a metal chloride which is soluble in cold water.
Which metal chloride which is insoluble in cold water.
(1)

copper chloride
lead chloride
magnesium chloride
potassium chloride

A

Lead chloride

122
Q

Sodium chloride has a melting point of 801 °C.
Explain why the melting point of sodium chloride is high. (2)

A

Strong electrostatic forces of attraction (1)
Between oppositely charged ions (1)
So requires a lot of heat energy to break/overcome these forces (1)

123
Q

Describe how you would test for the presence of chloride ions in a solution of sodium chloride. (3)

A

Add dilute nitric acid (1)
Add silver nitrate solution (1)
A white precipitate/solid is formed (1)

124
Q

Magnesium has an electronic configuration of 2.8.2.
Oxygen has an electronic configuration of 2.6.
Explain, in terms of their electronic configurations, how magnesium and oxygen atoms react to form the ionic compound magnesium oxide, MgO, and include a description of the structure of solid magnesium oxide. (6)

A

ion formation:
• magnesium atoms lose electrons
• each magnesium atom loses two electrons
• to acquire full outer shell
• magnesium (configuration) becomes 2.8
• forms Mg2+ ion • electrons transferred to oxygen atoms
• oxygen atoms gain electrons
• each oxygen atom gains two electrons
• oxygen (configuration) becomes 2.8
• to acquire full outer shell
• forms 02 ion

structure:
• magnesium ions attract oxide ions
• due to opposite charges
• ions pack close together
• ratio of ions 1: 1
• ions arranged in lattice
• giant (ionic) (structure)

125
Q

State the maximum number of covalent bonds formed by a carbon atom in a diamond crystal. (1)

A

4

126
Q

Which of the following statements about diamond and graphite is true? (1)

they are both good conductors of electricity
they are both soluble in water
they both cut glass
they both have high melting points

A

they both have high melting points

127
Q

Explain, in terms of its structure, why graphite is able to be used as a lubricant. (2)

A

Layers can slide over each other (1)
Because of the weak forces between layers of atoms (1)

128
Q

Sodium chloride and water have very different properties.

Sodium chloride is an ionic substance, a crystalline solid at room temperature and has a high melting point. It conducts electricity when molten or in aqueous solution.
Water is a covalent substance, liquid at room temperature and a very poor conductor of electricity.

Explain these properties of sodium chloride and water in terms of the particles present and the forces between them. (6)

A

Sodium chloride:
• contains {charged particles/ ions}
• contains Na+ and Cl-
• (regular) giant lattice (hence crystalline)
• strong (electrostatic) forces (of attraction) between ions/strong ionic bonds
• a lot of (heat) energy is needed to overcome/break these forces (hence high melting point)
• ions are free to move (so it conducts electricity) when molten/dissolved in water

Water:
• covalent bonds between (hydrogen and oxygen) atoms/ (pair of) electrons shared between atoms
• contains molecules (H2O)
• simple molecular/covalent
• weak intermolecular forces between molecules
• not much energy needed to separate these molecules (hence liquid at room temperature)
• does not contain any ions/delocalised electrons (hence does not conduct electricity)

129
Q

Nitrogen and oxygen are present in the air.
In industry, nitrogen and oxygen are obtained from air.
Give the name of the process used. (1) ………..……
State why the air is cooled before the start of the process. (1) ………………

A

Fractional distillation (1)
To make it a liquid (1)

130
Q

Complete the sentence:
Oxygen has a low boiling point because there are…
(1)

weak covalent bonds between the oxygen atoms
weak covalent bonds between the oxygen molecules
weak forces of attraction between the oxygen atoms
weak forces of attraction between the oxygen molecules

A

weak forces of attraction between the oxygen molecules

131
Q

The electronic configuration of oxygen (atomic number 8) is 2.6.
Give the electronic configuration of carbon (atomic number 6). (1)

A

2.4

132
Q

Particle Z has:

18 electrons
18 neutrons
16 protons
Explain whether it’s a negative ion. (2)

A

A negative ion must have more electrons than protons in a particle. (1)
Therefore, particle Z will have a 2- charge (1)

133
Q

The table shows the names and formulae of 3 ions.

calcium = Ca^2+
nitrate = NO3^–
phosphate = PO4^3–

What is the formula of calcium nitrate? (1)

Ca2NO3
CaNO3
Ca3NO2
Ca(NO3)2

A

Ca(NO3)2

134
Q

The number of oxygen atoms in the formula Ca3(PO4)2 is… (1)

A

8

135
Q

The table gives some information about the elements sodium = metal - 11 electrons in an atom
sulfur = non-metal - 16 electrons in an atom

Sodium sulfide is an ionic compound.
Describe, in terms of electron transfer, how sodium atoms react with sulfur atoms to form sodium sulfide.
Your description should include the charges on the ions formed. (4)

A

Sodium has 1 electron in its outer shell (1)
Sodium loses electrons (1)
Sodium loses 1 electron per atom (1)
To form Na+ (1)

Sulphur has 6 electrons in its outer shell (1)
Sulphur gains electrons (1)
Sulphur gains 2 electrons per atom (1)
To form S2^- (1)
2 sodium ions combine with 1 sulphur ion to make Na2S (1)

136
Q

Explain the difference in the ability of solid sodium chloride and molten sodium chloride to conduct electricity in terms of their structures. (6)

A

Solid:
Regular lattice arrangement of ions
Sodium and chloride ions held together by strong electrostatic forces of attraction between oppositely charged ions, which are closely packed together.

Molten:
Heat energy overcomes strong electrostatic forces of attraction between oppositely charged ions. Ions can move, therefore, conducts when molten.

137
Q

Describe, in terms of electrons, how a copper atom, Cu, becomes a copper ion, Cu2+ (2)

A

Loses electrons (1)
Loses 2 electrons (1)

138
Q

Some of the elements in the periodic table are metals.
The electronic configuration of a metal is 2.8.3
Which group and period of the periodic table is this metal is found? (2)

A

Group: 3
Period: 3

139
Q

Calcium reacts with water to form calcium hydroxide, Ca(OH)2, and hydrogen, H2.
Ca(s) + 2H2O(l) → Ca(OH)2(s) + H2(g)
Describe what would be seen when a piece of calcium is dropped into a container of water. (2)

A

Hydrogen produced as a gas, so bubbling/fizzing is seen (1)
Calcium hydroxide produced as a solid, so the water would go cloudy/white precipitate formed (1)

140
Q

Magnesium reacts very slowly with cold water but it reacts faster with steam, H2O,
and forms magnesium oxide, MgO, and hydrogen.
Write the balanced equation for the reaction between magnesium and steam. (2)

A

Mg + H2O → MgO + H2

LHS (1)
RHS (1)

141
Q

The electronic configurations of magnesium and calcium are:
magnesium = 2.8.2
calcium = 2.8.8.2
When magnesium and calcium react with water they form positive ions.
Suggest an explanation, in terms of their electronic configurations, why calcium is more reactive than magnesium. (2)

A

In calcium, the outermost electrons are further from the nucleus (1)
Therefore, the electrons are easier to remove (1)

142
Q

An atom of element B (period 4) contains more protons than an atom of element A (period 3).
State how many more protons there are in an atom of element B than in an atom of element A.

A

8 protons

143
Q

An element in group 0 in the periodic table is used to fill filament light bulbs.
Explain why this element is suitable for this use. (2)

A

This element is inert/unreactive/noble gas (1)
It has a full outer shell (1)
Prevents the filament from reacting (1)

144
Q

The elements in group 3 of the periodic table are boron, aluminium, gallium, indium and thallium.
(Elements can be classified as metals or non-metals.
Explain, using its position in the periodic table, whether indium is a metal or a non-metal. (2)

A

Metal (1)
Because its below the line dividing metals from non-metals/boron is the only non-metal in group 3 (1)

145
Q

A sample of boron contains the two isotopes, boron-10 and boron-11.
The relative atomic mass of boron is 10.8
Give the reason why the relative atomic mass is closer to 11 than 10. (1)

A

More atoms of boron have a relative atomic mass number of 11 than 10 (1)

146
Q

The formula of aluminium nitrate is Al(NO3)3
State the total number of atoms in the formula Al(NO3)3 (1)

A

13

147
Q

The electronic configuration of oxygen (atomic number 8) is 2.6.
Give the electronic configuration of carbon (atomic number 6). (1)

A

2.4

148
Q

Figure 13 shows a model (equally sized circles in ordered rows) of how particles are arranged in a solid.
State two ways in which this model fails to accurately represent a crystal of sodium chloride. (2)

A

Particles are the same size, when they should be different sizes (1)
Model is in 2d, crystals are 3d (1)

149
Q

Magnesium oxide has a melting point of 2852 °C.
Explain why magnesium oxide has such a high melting point. (3)

A

Very strong bonds (1)
Between 2+ cations and 2- anions (1)
So requires a lot of energy to separate magnesium and oxide ions to melt the solid (1)

150
Q

Carbon dioxide can be formed by the reaction of calcium carbonate, CaCO3, with dilute hydrochloric acid.
Write the balanced equation for this reaction. (3)

A

CaCO3 + 2HCl → CaCl2 + H2O + CO2

151
Q

A test tube was filled with hydrogen chloride gas.
The test tube was inverted in water and left.
The liquid level rose up to the top of the test tube.
Explain what was formed in the test tube after the water had entered. (2)

A

Hydrogen chloride dissolves in water (1)
Forms hydrochloride acid (1)

152
Q

When chlorine is bubbled into potassium bromide solution, the solution turns orange.
Explain why this happens. (2)

A

Orange colour due to bromine (1)
Chlorine displaces bromine (1)
Because chlorine is more reactive than bromine (1)

153
Q

Barium sulfate can be prepared as a white precipitate.
Describe how you could prepare a pure, dry sample of barium sulfate from barium chloride solution and sodium sulfate solution. (3)

A

Mix solutions (1)
Filter (1)
Wash precipitate/solid with water (1)
Dry solid/precipitate with water (1)

Chemistry (10 decks)

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