C1 Atoms and C2 The Periodic Table

Question 1

What is an atom?

Answer 1

The smallest part of an element that can exist.

Question 2

What is an element?

Answer 2

A substance containing only one type of atom

Question 3

What is a molecule?

Answer 3

2 or more atoms chemically bonded together

Question 4

What is a compound?

Answer 4

2 or more elements chemically bonded together

Question 5

What does aqueous(aq) mean?

Answer 5

dissolved in water

Question 6

What are the relevant masses and charges of protons, neutrons and electrons?

Answer 6

Proton - mass 1, charge +1
Neutron - mass 1, charge 0
Electron - mass 0, charge -1

Question 7

What is the law of conservation of mass?

Answer 7

No atoms are created or destroyed in a chemical reaction so the total mass of the products is equal to the total mass of the reactants.

Question 8

What elements form diatomic molecules?

Answer 8

• Group 7 elements, e.g. F, Cl
• Oxygen (O)
• Hydrogen (H)
• Nitrogen (N)

Question 9

What is a solvent?

Answer 9

A substance the solute dissolves into e.g. water

Question 10

What is a solute?

Answer 10

A substance that dissolves into a solvent, e.g. sugar

Question 11

What is a mixture?

Answer 11

2 or more substances that are not chemically bonded together.

Question 12

What is filtration used for and how does it work?

Answer 12

Filtration is used to seperate an insoluble substance from a solvent/solution.
It works by pouring the mixture into a funnel with filter paper in which collects the insoluble substance as residue as the particles are too large to pass through the holes in the filter paper, whereas the solvent or solution passes through the filter paper as the filtrate as its particles are small enough to pass thrugh the holes.

Question 13

What is crystallisation and how does it work?

Answer 13

It is used to obtain pure salt from a solution, e.g. NaCl from a salt solution.
It works by evaporating the solvent (water) from the solution leaving salt crystals behind.

Question 14

What is simple distillation and how does it work?

Answer 14

Distillation is used to separate a solvent from a solution while collecting the solvent, e.g. separating water from seawater.
The solution is heated and boiled until the substance with the lower boiling point evaporates and the vapour given off then passes into the condenser with cold water running through it where it condenses back into a liquid that is then collected in a beaker.

Question 15

What is the mobile phase?

Answer 15

the solvent

Question 16

What is the stationary phase?

Answer 16

The paper

Question 17

How do you calculate the Rf value in chromatography?

Answer 17

Rf = distance travelled by substance(measured from center of spot)/ distance travelled by solvent

Question 18

How does chromatography work?

Answer 18

As the solvent travels up the chromatography paper, it dissolves the components in the sample and components separate due to differences in solubility. The more soluble the substance, the further up the paper it is carried.

Question 19

What is fractional distillation and how does it work?

Answer 19

Fractional distillation is used to separate mixtures of miscible liquids which it is difficult to get pure samples of as the liquids give off vapour before they boil.
It is very similar to simple distillation but a fractionating column is added containing glass beads which the vapours must pass through before reaching the condenser. The fractionating column is hottest at the bottom and coldest at the top, the substance with the higher boiling point will condense more readily on the cooler glass beads nearer the bottom of the column and drip back into the flask beneath leaving a purer substance to be collected.

Question 20

What is the solid sphere model of the atom?

Answer 20

In 1803 John Dalton suggested that atoms were small solid balls of matter that couldn’t be broken down any further.

Question 21

What is the plum pudding model of the atom?

Answer 21

In 1904, JJ Thomson put forward the plum pudding model which suggested atoms were spheres of positive charge scattered with negatively charged electrons.

Question 22

What was Rutherford’s experiment?

Answer 22

In 1911, dense, positively charged alpha particles were shot at a thin gold foil, most of the alpha particles went directly through the foil but some were deflected back. This proved that atoms are mostly empty space and that there was a small, dense positively charged nucleus in the centre of the atom.

Question 23

What is the nuclear model?

Answer 23

In 1911, Ernest Rutherford suggested the nuclear model, which had a small, dense positively charged nucleus surrounded by electrons randomly moving about.

Question 24

What is the Bohr model of the atom?

Answer 24

In 1913, Niels Bohr revised the nuclear model, putting the electrons in fixed energy levels or shells.

Question 25

Why was the Bohr model adapted?

Answer 25

In 1932, James Chadwick discovered neutrons and the Bohr model was adapted to have both protons and neutrons in the nucleus.

Question 26

What is the atomic number?

Answer 26

The number of protons in each atom of an element.

Question 27

What is the mass number?

Answer 27

The number of protons + the number of neutrons.

Question 28

How do you calculate the number of neutrons in an element atom?

Answer 28

mass number-atomic number

Question 29

How are electrons configurated?

Answer 29

Electrons are arranged in shells, the electron arrangement is 2,8,8 meaning there can be up to 2 atoms in the first shell, 8 in the second and 8 in the third.

Question 30

What is an ion?

Answer 30

An ion is an atom or group of atoms with a positive or negative charge due to loss or gain of electrons.

Question 31

What is an isotope?

Answer 31

Atoms of the same element that have the same number of protons and electrons but different numbers of neutrons.

Question 32

How do you calculate relative atomic mass?

Answer 32

Ar = Σ(mass of isotope x relative abundance) / 100 (total abundance)
e.g
ArCl = (35x75.5)+(37x24.5)/100
= 35.49 = 35.5 on periodic table

Question 33

What does inert mean?

Answer 33

unreactive

Question 34

Why are noble gases inert?

Answer 34

Noble gases are inert because they have a complete outer shell of electrons making them stable.

Question 35

What does an oxygen atom need to become stable?

Answer 35

Oxygen needs 2 more electrons to be stable, but as it gains those electrons it gains a charge of -2 written as O^2-.

Question 36

How do you draw the electron structure of an element (with boron as an example)?

Answer 36

You write the chemical symbol of the element in the middle surrounded by circles with the number of electrons in the element marked on them using the electron arrangement (2,8,8).
For example, you would draw boron by putting a B in the middle surrounded by 2 circles, the inner with 2 electrons on it and the outer with 3 electrons on it.

Question 37

What is the connection between group numbers on the periodic table and electron structure?

Answer 37

The group number of an element is the same as the number of electrons in its outer shell.

Question 38

How do you draw an ion?

Answer 38

You draw an ion very similarly to an element but you must add square brackets ,[ ],around the atom, label the charge in the top right outside the brackets (as when writing an ion’s symbol) and also add or take away electrons in the shell so it is complete.
For example for lithium, you remove the electron in the outer shell leaving it with a charge of +1 and for fluorine, to get a fluoride ion you add an electron to its outer shell leaving a charge of -1.

Question 39

How did Mendeleev arrange his table?

Answer 39

• He ordered elements by their increasing atomic weight (relative atomic mass)
• He arranged elements by putting those with similar chemical properties below each other in groups.
• Mendeleev made a few changes:
  >He left gaps for yet to be discovered elements
  >He swapped round some elements so that their properties matched the rest of the elements in the same group, e.g Iodine and tellurium

Question 40

How was Mendeleev’s table proved?

Answer 40

Mendeleev predicted the properties of undiscovered elements such as gallium and when the elements were finally discovered, the element’s properties matched those predicted by Mendeleev.

Question 41

What happens with properties as you go down Group 1?

Answer 41

Physical Properties
>Elements become softer
>Melting + boiling points decrease
>atomic size increases
Chemical properties
>Reactions with water become more vigorous
>Reactions with oxygen to form metal oxides increase in speed

Question 42

What happens when lithium, sodium and potassium react with oxygen?

Answer 42

They react to create a metal oxide.
Observations:
Lithium - burns with a red flame to give a white solid
Sodium - burns with a yellow/orange flame to give a white solid
Potassium - burns with a purple flame to give a white solid
Equation example:
4Li +O2 —> 2Li2O

Question 43

What happens when lithium, sodium and potassium react with chlorine?

Answer 43

They react to make a metal chloride
Observations:
Lithium - bright yellow flame, burns to give white solid
Sodium - bright white flame, burns to give white solid
Potassium - bright white flame, burns to give white solid
Equation example
2Li + Cl2 –> 2LiCl

Question 44

What happens when lithium, sodium and potassium react with water?

Answer 44

They react to make a metal hydroxide + hydrogen
Observations:
Lithium - fizzing, steadily gets smaller, moves and floats on surface of water
Sodium - fizzing rapidly , melts into ball, moves and floats on surface of water, may produce yellow flames
Potassium - fizzing, lilac flames, moves and floats on surface of water, over very quickly, may cause small explosion at end
Equation Example
2Li + 2H2O –>2LiOH + H2

Question 45

Describe how sodium reacts with chlorine (3)

Answer 45

Chlorine is a pale yellow/green gas and sodium is a silvery metal, when they react a bright white flame is produced and they burn to create white crystals

Question 46

Why do Group 1 metals get more reactive down the group ?

Answer 46

• Atoms get bigger/number of shells increases
• Distance between outer electron and nucleus increases
• So the forces of attraction between positively charged nucleus and negatively charged outer electron become weaker
• Therefore, outer electron is lost more easily down group 1.

Question 47

What are Group 7’s physical properties?

Answer 47

Low melting and boiling points (increase down group)
* F - colourless gas at room temp
* Cl - greenish-yellow gas at room temp
* Br - dark reddish-brown liquid
* I - gray solid crystals (purple vapour, appears brown in water)
Halogens are volatile(evaporate easily)

Question 48

What happens to reactivity down Group 7? why?

Answer 48

• Halogens get less reactive as you go down the group.
• Atoms get bigger/number of shells increases
• Distance between outer electron and nucleus increases
• So the forces of attraction between positively charged nucleus and negatively charged outer electron become weaker
• Therefore, down Group 7, the outer electron is less easily gained

Question 49

What are displacement reactions?

Answer 49

A chemical reaction where a more reactive element displaces a less reactive element from its compound.
e.g. Cl2 + 2KI –> 2KCl + I2

Question 50

What colour are halogens when aqueous?

Answer 50

Cl2(aq) - colourless
Br2(aq) - orange
I2(aq) - brown

Question 51

What are some physical properties of transition metals?

Answer 51

• They are good conductors of heat and electricty
• Hard
• Strong
• High Density
• High Melting and boiling point (other than mercury)

Question 52

Why are transition metals more suitable for a car than Group 1 metals?

Answer 52

Transition metals hold their shape, don’t melt easily and don’t react with water or oxygen.

Question 53

How do you tell transition metal and group 1 compounds?

Answer 53

Transition metals form coloured compounds whereas Group 1 metals form white compounds.

Question 54

Why do transition metal compounds include roman numerals?

Answer 54

Transition metals can change how many electrons are lost in their outer shell, forming different charged ions, indicated by the roman numerals. e.g. copper(II) chloride has a Cu2+ ion.

Question 55

What is a common use of transition metals?

Answer 55

Transition metals (and their compounds) act as catalysts which are substances that increase the rate of a reaction without being used up.