topic 1 - atomic structure and the periodic table

Question 1

what’s the radius of an atom

Answer 1

0.1 nanometres

Question 2

what is the mass number

Answer 2

number on the top, tells you total number of protons and neutrons in the atom

Question 3

what is the atomic number

Answer 3

number on bottom, tells you number of protons there are

Question 4

how do you work out the number of neutrons in an atom

Answer 4

subtract the atomic number from the mass number

Question 5

an atom of gallium has an atomic number of 31 and a mass number of 70. give number of protons, neutrons and electrons in the atom

Answer 5

p12 q1

Question 6

what is an isotope

Answer 6

isotopes are different forms of the same element which have the same number of protons but a different number of neutrons.
isotopes have the same atomic number but a different mass number

Question 7

what’s the formula for relative atomic mass

Answer 7

relative atomic mass(Ar) = sum of (isotope abundance x isotope mass number) divided by sum of abundances of all isotopes

Question 8

a substance consists of atoms which all have the same number of protons and electrons but different numbers of neutrons explain why this substance is an element

Answer 8

p13q1

Question 9

what is a compound

Answer 9

a compound is a substance formed from two or more elements, the atoms of each are in fixed proportions throughout the compound and they’re held together by chemical bonds

Question 10

what’s a mixture

Answer 10

Two or more substances that are not joined together. The substances can be elements, compounds, or both.

Question 11

what is a pure substance

Answer 11

a pure substance consists only of one element
or one compound

Question 12

what is filtration

Answer 12

Filtration is used to separate an insoluble
solid from a liquid. It is useful for separating sand from a mixture of sand and water, or
excess reactant from a reaction mixture.

Question 13

Why does iodine have a higher boiling point than chlorine?

Answer 13

The forces between iodine molecules are stronger

Question 14

Chlorine displaces bromine from bromide ions.
Cl2 + 2Br- → 2Cl- + Br2
What happens in this reaction?

Answer 14

Bromide ions lose electrons and are oxidised

Question 15

Group 1 elements have ______________ melting points.
Group 1 elements are ________ metals.

Answer 15

Group 1 elements have low melting points.
Group 1 elements are soft metals.

Question 16

Why is aluminium positioned in group 3 of the periodic table?

Answer 16

It has three electrons in its outer energy level/outer shell.

Question 17

Substance Boiling point
Ethanol 78°C
Water 100°C

Use data from table 1 to explain why ethanol and water can be separated using fractional distillation.

Answer 17

Ethanol has a lower boiling point than water. [1 mark]
On heating, ethanol vapour leaves the mixture of liquids first. [1 mark]
The ethanol vapour can be cooled and condensed separately. [1 mark]

Question 18

Describe how a sample of copper chloride crystals could be made from copper carbonate and dilute hydrochloric acid

Answer 18

Add excess copper carbonate to dilute hydrochloric acid. [1 mark]
Filter. [1 mark]
Heat filtrate to evaporate some water. [1 mark]
Leave to cool. [1 mark]

Question 19

Group 1 of the periodic table contains the alkali metals lithium, sodium and potassium.
The alkali metals show a pattern in their reactivity with water.
This pattern is shown when small pieces of lithium, sodium and potassium are added separately to water.
Describe the reactions and explain the pattern in reactivity.

Answer 19

Description:
effervescence/fizzing/bubbles
float/on surface
move
produce hydrogen (may be shown in word or balanced equation)
an alkaline/metal hydroxide solution (may be shown in word or balanced equation)
gets smaller/disappears/dissolves
reactivity increases with increasing atomic number/down the group/potassium effervesces more than sodium and lithium/potassium moves faster than sodium or lithium
sodium and potassium melt/form a (silver-coloured) ball
hydrogen burns when potassium/ sodium react
potassium gives a lilac flame/sodium gives a yellow flame
universal indicator added to water turns blue/purple

Explanation:
(group 1 metals) react by losing one electron
electron is more easily lost with increasing atomic number/down the group
electron/ outer shell is further away from nucleus/atomic radius increases/there are more electron shells with increasing atomic number/down the group
more shielding (of outer electron)/less attraction between nucleus and outer electron/ more shells between outer electron and nucleus with increasing atomic number/down the group

Question 20

which method of distillation would you use to separate liquids with similar boiling points

Answer 20

fractional distillation

Question 21

what is the difference between a compound and a mixture

Question 22

what is the name of the pattern formed from carrying out paper chromatography

Question 23

which method of separation is useful to separate an insoluble solid from a liquid

Answer 23

filtration

Question 24

who discovered that the plum pudding model was wrong

Question 25

who first devised an experiment that proved the existence of the neutron

Question 26

why did mendeleev leave gaps in the periodic table

Question 27

give three properties specific to transition metals

Answer 27

1) they can have more then one ion
2) often coloured compounds that contain them are colourful
3) they make good catalysts

Question 28

state three trends as you go down group one

Answer 28

-increasing reactivity
-lower melting and boiling points
-higher relative atomic mass

Question 29

state the products of the reaction of sodium and water

Answer 29

sodium + water = sodium hydroxide + hydrogen

Question 30

state the differences between group one and transition metals for the following properties
1) hardness
2)reactivity
3)melting points

Answer 30

1) group one elements are much less dense, strong and hard than the transition metals
2) group one metals are much more reactive then transition metals

Question 31

how do the boiling points of halogens change as you go down the group from fluorine to astatine

Answer 31

they increase

Question 32

what is the charge of the ions that halogens form when they react with metals

Answer 32

1- ions

Question 33

predict whether iodine is displaced by chlorine in a solution of potassium iodide

Answer 33

chlorine will displace iodine in an aqueous solution because potassium iodide is a salt- more reactive halogens replace less reactive ones

Question 34

what is the trend in the boiling point as you go down group 0

Answer 34

the boiling points of the noble gases increase as you move down the group along with increasing relative atomic mass

Question 35

why do the boiling points increase in noble gases as you go down group 0

Answer 35

the increase in boiling point is due to an increase in the number of electrons in each atom leading to greater intermolecular forces between them which need to be overcome.