Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Chemistry Alevel OCR > 3.1 The Periodic Table > Flashcards

3.1 The Periodic Table Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Chemistry flashcards Periodic Table flashcards Chemistry 101 flashcards Organic Chemistry 101 flashcards
1
Q

Define the first ionisation energy

A

-the energy required to remove one electron from each atom in one mole of the gaseous element to form one mole of gaseous 1+ ions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Describe and explain the electrical conductivity of sodium oxide and sodium in their solid and molten states

(5marks)

A

-sodium conducts in the solid and molten states
-sodium is an alkali metal so has delocalised electrons in both solid and liquid state
-sodium oxide conducts when molten and not when solid
-as molten sodium oxide has ions which are mobile
-solid sodium oxide has ions which are fixed in position in a lattice

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are 3 examples of anions?

A

-carbonate ions CO3^2-
-sulfate ions SO4^2-
-halide ions- Cl^-, Br^-,I^-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What do carbonate ions form when they react with acids?

A

-water and carbon dioxide and a salt

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the method and positive test observations for testing for carbonate ions ?

A

.Add a dilute strong acid to the suspected carbonate.
.Collect any gas formed and pass it through limewater

Positive test
•Fizzing/colourless gas is produced.
• The gas turns limewater cloudy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What do sulfate ions react with barium ions to form?

A

-barium sulfate BaSO4
an insoluble salt which is aqueous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the test for sulfate ions (SO4^2-) and the positive observations?

A

• Add dilute hydrochloric acid and barium chloride to the suspected sulfate
Positive results
•a white precipitate of barium sulfate is produced.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What do halide ions form when reacted with silver ions?

A

Different coloured halide precipitates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the method for testing for halide ions (Cl-,Br-,I-)?

A

-dissolve suspected halide in water
-add an aqueous solution of silver nitrate
-note the colour of any precipitate formed
-add aqueous ammonia to distinguish the colour , adding first dilute then concentrated
-note the solubility of the precipitate in aqueous ammonia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the positive test observations for silver chloride?

A

-white precipitate
-soluble in dilute aqueous ammonia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the positive test observations for silver bromide?

A

-cream precipitate
-soluble only in concentrated ammonia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the positive test observations for silver iodide?

A

-yellow precipitate
-insoluble in both dilute and concentrated aqueous ammonia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is an example of a cation?

A

-the ammonium ion NH4^+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does the ammonium ion react with hydroxide ions?

A

-to produce ammonia and water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the method and positive test results for ammonium ions NH4^+?

A

• Add sodium hydroxide solution to the suspected ammonium compound and warm very gently.
• Test any gas evolved with red litmus paper

Positive results
• Ammonia gas will turn red Litmus paper blue.
• Ammonia gas has a distinctive smell. (Ammonia gas is hazardous )

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Explain the variation in melting points across period 2 and 3

A

-group 1 and 2 the elements have a giant metallic structure so there are strong forces between the positive ions and negative delocalised electrons
-in group 13 and 14 the elements have a giant covalent structure meaning there are strong covalent bonds that have to be overcome
-as well as this the nuclear charge increases as well as the number of electrons in the outer shell- causing stronger attraction
-Meaning a high amount of energy is needed to overcome these bonds and forces so they have a high melting point
-However in group 14 and 15 there is a sharp decrease in melting point as these elements have simple molecular structure held together by weak intermolecular forces between the molecules
-in group 15 and 18 the melting points remain relatively low as they also have a simple molecular structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What colour compounds do group 2 metals form?

A

• form colourless (white) compounds.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What ions do group 2 elements form?

A

-they lose 2 electrons in redox reactions to form 2+ ions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What block of the periodic table are group 2 elements in?

A

S-block

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the trend in reactivity going down group 2?

A

-reactivity increases going down the group -ionisation energies show that the two outer electrons are lost more easily going down the group to barium
-as each successive element has its outer electrons in a higher energy level ,has a larger atomic radius and feels more electron shielding from the positive pull of the nucleus. So they have less nuclear attraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What type of agent are group 2 elements?

A

-they are strong reducing agents
-they are oxidised in reactions to form 2+ ions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Write an equation for the first and second ionisation of a group 2 element

A

1st
Mg (g)—> Mg^+(g) + e^-

2nd
Mg^+(g)—-> Mg^2+(g) +e^-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How do group 2 elements react with oxygen?

A

-they react vigorously with oxygen -this is a redox reaction
-the product is an ionic oxide for example calcium oxide CaO
2Mg +O2 ———> 2MgO

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How do group 2 elements react with water ?

A

-all group 2 elements ,except beryllium, react with water to form hydroxides e.g.Mg(OH)2
And hydrogen gas
-this is a redox reaction

-Mg reacts with water very slowly. Moving further down the group, each metal reacts more vigorously with water

25
Q

What is reduced and what is oxidised when group 2 elements react with water ?

A

-the metal is oxidised and one hydrogen atom from each water molecule is reduced

26
Q

How do group 2 elements react with dilute acids?

A

All the group 2 elements, except Be, react with dilute acids to form a salt and hydrogen gas. The reaction becomes more vigorous moving down the group.

27
Q

What is oxidised and what is reduced in the reaction of group 2 elements and dilute acids?

A

The metal is oxidised and hydrogen is reduced

28
Q

How do group 2 oxides react with water ?

A

Group 2 oxides react with water to form metal hydroxides. The general reaction for this, where the group 2 metal is M is:
MO(s) +H2O(l)——> M(OH)2(aq)
The metal hydroxides are soluble in water,and form alkaline solutions with water because they release OH- ions. The typical pH of these solutions is between 10 and 12.

29
Q

What is the typical pH of an alkaline solution where a group 2 element has been put in water?

A

Between 10-12

30
Q

How do the solubility of group 2 metal hydroxides change?

A

-the solubility of the hydroxides in water increases down the group
-when a hydroxide is more soluble it means it will release more OH- ions and so will make a more alkaline solution with a higher pH

31
Q

What are 3 examples of how solubility of group 2 metal hydroxides change down the group?

A

• Beryllium is at the top of group 2 beryllium oxide is insoluble in water.
• Magnesium forms Mg(OH)2(s), which is only slightly soluble in water - the resulting solution is dilute with a comparatively low OH- (aq) concentration.
• Ba(OH)2(s) is much more soluble in water than Mg(OH)2(s), and so has a higher OH- (aq) concentration. The resulting solution is more alkaline than a solution of Mg(OH)2

32
Q

What are the oxides , carbonates and hydroxides of group 2?

A

-they are basic
-they will react with an acid to form a salt and water
E.g

MgO(s) + 2HCl(aq) —->MgCl2(aq) + H2O(l)

Ca(OH)2(s) +2HCl(aq) —>CaCl2(aq) +2H20(l)

33
Q

What group 2 compound is used in agriculture to neutralise acidic soils?

A

-calcium hydroxide - Ca(OH)2
-referred to as lime

34
Q

What group 2 element compounds are used as ‘antacids’ to treat indigestion?

A

-milk of magnesia contains magnesium hydroxide -Mg(OH)2

-The magnesium hydroxide in the milk of magnesia neutralises the excess acid producing a salt and water:
Mg(OH)2 + 2HCI —-> MgCl2 + 2H20

-CaCO3 is also used as antacids

35
Q

How is calcium carbonate CaCO3 used in construction?

A

-present in both limestone and marble
-also used in the manufacture of glass and steel

-however a disadvantage is that they react with acid readily. So acid rain leads to gradual erosion

CaCO3(s) + 2HCl(I)—-> CaCl2(aq) + H2O(l) + CO2(g)

36
Q

What are 2 properties of the halogens (group17)?

A

-have low melting and boiling points
-exist as diatomic molecules

37
Q

What block are group 17 in ?

A

P block

38
Q

What is the trend in boiling points down the halogens?

A

-the boiling point increases and the physical state changes from gas to liquid to solid
-because each successive element has an extra shell of electrons leading to a higher level of London forces (induced dipole-dipole) between the molecules

39
Q

How reactive are halogens?

A

-they are very reactive and highly electronegative
-they are strong oxidising agents
-they gain one electron to form 1- ions

40
Q

Why does the reactivity and oxidising power of halogens decrease moving down the group?

A

-the atomic radius increases as the nuclear pull (the protons)are further away from the electrons
-the electron shielding increases
-the ability to gain an electron in the p sub-shell and form 1- ions decreases

41
Q

What will a more reactive halogen do when reacted with a less reactive halogen?

A

-a more reactive halogen will oxidise and displace a halide of a less reactive halogen -this is called a displacement reaction

42
Q

What is the colour of Cl2 in water and in cyclohexane ?

A

In water- pale green
In cyclohexane-pale green
Chlorine oxidises both Br- and I- ions

43
Q

What is the colour of Br2 in water and cyclohexane?

A

In water- orange
In cyclohexane-orange
Bromine can only oxidise I- ions

44
Q

What is the colour of I2 in water and cyclohexane?

A

In water-brown
In cyclohexane-violet
Iodine does not oxidise either Cl- or Br- ions

45
Q

What is the definition of disproportionation?

A

-the oxidation and reduction of the same element in a redox reaction

46
Q

How is the reaction of chlorine with water an example of a disproportionation reaction?

A

-chlorine reacts with water forming a mixture of hydrochloric acid (HCl) and chloric(I) acid (HClO)
-this is a disproportionation reaction as chlorine is both reduced and oxidised

47
Q

How is the formation of bleach an example of a disproportionation reaction ?

A

-chlorine is reacted with cold dilute aqueous sodium hydroxide at room temperature
-chlorine is both oxidised and reduced in this reaction

Cl(aq) +2NaOH(aq) —->NaCI(aq) +NaCIO(aq) + H20(l)

48
Q

What are the benefits of using chlorine in water and the associated risks?

A

Benefits
-kills bacteria- has been credited with virtually eradicating some water carried diseases (cholera and dysentery)

Risks
-hazards of toxic chlorine gas
-possible risks from the formation of chlorinated hydrocarbons , which are suspected of causing cancer

49
Q

How is the modern periodic table arranged ?

A

-in order of increasing atomic (proton) number

50
Q

What do groups contain?

A

Elements that have similar chemical properties

51
Q

What is periodicity?

A

-the trend in properties that is repeated across each period
-can be used to make predictions about the likely properties of an element and its compounds

52
Q

Why does ionisation energy increase across each period?

A

-the number of protons increases so there is a higher attraction to the electrons
-electrons are added to the same shell , so the outer shell is drawn inwards slightly so smaller atomic radius so higher nuclear charge
-electron shielding will hardly change as there is the same number of inner shells

53
Q

Why is there a small decrease in first ionisation energies between group 2 and 13 elements ?

A

As group 13 elements have their outermost electron in a p-orbital whereas group 2 elements have theirs in an s-orbital.
P-orbitals have a slightly higher energy than s-orbitals and so are slightly further away from the nucleus.Meaning that electrons in these orbitals are slightly easier to remove so have lower ionisation energies
As well as this there is also a decrease in atomic radius moving across a period increasing the nuclear charge

54
Q

Why is there a small decrease in first ionisation energies between group 15 and 16?

A

-In group 15 each of the p-orbitals contain only a single electron
-however in group 16 the outermost electron is now spin-paired in the px orbital.
-meaning it experiences some repulsion making the first outer electron slightly easier to remove
-there is also a decrease in atomic radius due to increased nuclear charge

55
Q

How does first ionisation energies change moving down a group?

A

-they decrease
-as the number of shells increases the distance of the outer electrons from the nucleus increases so there is a weaker force of attraction on the outer electrons
-more inner shells so more electron shielding from the nuclear charge , so there is a weaker attraction
-atomic radius increases

56
Q

What is the chemical formula for ammonia?

A

NH3

57
Q

Which particles are attracted in metallic bonding?

A

Cations and delocalised electrons

58
Q

Which particles are attracted in metallic bonding?

A

Cations and delocalised electrons

59
Q

What is the equation for the formation of bleach ?

A

Cl(aq) +2NaOH(aq) —->NaCI(aq) +NaCIO(aq) + H20(l)

Chemistry Alevel OCR (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions