Atomic structure and the periodic table- Chemistry Paper 1

Question 1

What’s an element?

Answer 1

A substance that contains only one type of atom

Question 2

What does the atomic number tell you?

Answer 2

The number of protons an element has

Question 3

What does the mass number tell you?

Answer 3

The total number of protons and neutrons in an atom?

Question 4

Is the atomic number the top or bottom number?

Answer 4

Bottom

Question 5

Is the mass number the top or bottom number?

Answer 5

Top

Question 6

What are isotopes?

Answer 6

Atoms of an element with the same number of protons, but a different number of neutrons. This means that they have the same atomic number but a different mass number

Question 7

what is the relative atomic mass of an element?

Answer 7

The relative atomic mass of an element is a weighted average of the masses of the atoms of the isotopes

Question 8

How do you work out the relative atomic mass?

Answer 8

sum of(isotope abundance X isotope mass number / sum of abundances of all isotopes

Question 9

What is a compoud?

Answer 9

A substance that contains 2 or more elements that are chemically bonded together.

Question 10

What’s a mixture?

Answer 10

A substance made up of 2 or more elements or compounds that aren’t chemically bonded together

Question 11

What methods are used to separate out mixtures?

Answer 11

Physical methods, as the components of mixtures aren’t chemically joined together

Question 12

What do physical methods of separation include?

Answer 12

• Chromatography
• Filtration
• Crystallisation
• Simple distillation
• Fractional distillation

Question 13

What is chromatography used for?

Answer 13

Separating mixtures made up of liquids of different colours

Question 14

Describe the process of paper chromatography

Answer 14

1) Draw a pencil line near the bottom of the sheet of chromatography paper
2) Spot the ink on the pencil line, then put the filter paper upright in a beaker of solvent.
3) Place a lid on top of the container to stop the solvent evaporating.
4) The solvent will move up the paper, carrying the ink with it
5) The different dyes will move up the paper at different rates, so the dyes will separate out and form spots in different places. Insoluble dyes will remain on the pencil line
6) The point the solvent reaches as it moves up the paper is the solvent front. When the solvent front has nearly reached the top of the paper, take the paper out of the beaker and draw a line with a pencil along the solvent front and leave to dry.
7) The end result is a pattern of spots called a chromatogram.

Question 15

Why shouldn’t the ink used in chromatography touch the solvent initially?

Answer 15

Because this could result in the ink being washed away

Question 16

Why is pencil used to draw the line at the bottom of the chromatography paper?

Answer 16

Because pencil is insoluble and so won’t dissolve in the solvent

Question 17

What is spotting?

Answer 17

Placing a dot of ink on the pencil line

Question 18

On some chromatograms, what does the number of spots you end up with tell you?

Answer 18

The number of different substances there were in the mixture

Question 19

What is the Rf value in paper chromatography?

Answer 19

The ratio between the distance travelled by the dissolved substance and the distance travelled by the solvent

Question 20

What is the mobile phase?

Answer 20

Where the molecules move, this can be either a liquid or a gas

Question 21

What is the stationary phase?

Answer 21

Where the molecules can’t move. This can be a solid or a really thick liquid

Question 22

Substances which travel the same distance during chromatography are…

Answer 22

the same

Question 23

During chromatography, substances will move depending on…

Answer 23

how strongly the attract with the stationary phase and how strongly they react with the mobile phase.