The Periodic Table

Question 1

What is the first ionisation energy of an element?

Answer 1

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.

Question 2

What three factors affect ionisation energy?

Answer 2

Atomic radius, nuclear charge and electron shielding/screening.

Question 3

How does atomic radius affect ionisation energy?

Answer 3

The larger the atomic radius, the smaller the nuclear attraction experienced by the outer electrons and thus the lower the ionisation energy. This is because the positive charge of the nucleus is further away from the outermost electrons.

Question 4

How does nuclear charge affect ionisation energy?

Answer 4

The higher the nuclear charge, the larger the attractive force on the outer electrons and thus the larger the ionisation energy.

Question 5

How does electron shielding/screening affect ionisation energy?

Answer 5

Inner shells of electrons repel the outer shell electrons because they are all negative. The more inner shells there are, the larger the atomic radius and the smaller the nuclear attraction therefore meaning the ionisation energy is lower.

Question 6

What is the trend in ionisation energies across a period of the periodic table?

Answer 6

The ionisation energy values show a general increase across each period.

Question 7

Why is there a decrease in ionisation energy between groups 2 and 13?

Answer 7

All elements in group 13 have their outermost electron in a p-orbital whereas group 2 elements have theirs in an s-orbital and p -orbitals have a slightly higher energy as s-orbitals are further away. This means it is slightly easier to remove an electron from an element in group 13

Question 8

Why is there a decrease in ionisation energy between groups 15 and 16?

Answer 8

In groups 13, 14 and 15, each of the p-orbitals contains only a single electron but in group 16, the outermost electron is spin-paired. Spin paired electrons experience more repulsion so are easier to remove.

Question 9

As you move down the group, how does ionisation energy change?

Answer 9

Moving down the group, the ionisation energies decrease as the number of shells increases increasing the atomic radius and shielding.

Question 10

What is a giant metallic lattice structure like?

Answer 10

A structure where the delocalised electrons are spread throughout the structure, where a lattice of positive ions (cations) are surrounded by a “sea” of delocalised electrons.

Question 11

What properties do giant ionic lattices have?

Answer 11

They have high melting and boiling points due to strong attractions between positive metal ions and delocalised electrons. They can conduct electricity due to delocalised electrons that can carry charge. They are also ductile and malleable.

Question 12

Between groups 1 and 14 how do MPs and BPs change?

Answer 12

They increase steadily because elements have giant structures and the nuclear charge increases.

Question 13

Between groups 14 and 15 how do MPs and BPs change?

Answer 13

There is a sharp decrease as elements have simple molecular structures instaid of giant structures. Simple structures have much weaker intermolecular forces.

Question 14

Between groups 15 and 18 how do MPs and BPs change?

Answer 14

They remain relatively low do to simple molecular structures with weak intermolecular forces.

Question 15

What are the physical properties of the group 2 elements?

Answer 15

• Reasonably high melting and boiling points
• Light metals
• Form colourless (white) compounds

Question 16

How do group 2 elements react with oxygen?

Answer 16

They react vigorously with oxygen in a redox reaction.

Question 17

How do group 2 elements react with water?

Answer 17

They react with water to form hydroxides and hydrogen gas. Going down the group, each element reacts more vigorously with water.

Question 18

How do group 2 elements react with dilute acids?

Answer 18

They form a salt and hydrogen gas. Going down the group, each element reacts more vigorously.

Question 19

How does the solubility of group 2 metal oxides change going down the group?

Answer 19

It increases as they produce more OH- ions as you go down.

Question 20

What are group 2 compounds used for?

Answer 20

neutralising soils, indigestion remedies, building and construction.

Question 21

What are the properties of the halogens?

Answer 21

• low melting and boiling points

- exist as diatomic molecules

Question 22

What is the trend in boiling points of the halogens?

Answer 22

The boiling point increases down the group due to each element having an extra shell of electrons meaning they have greater London forces.

Question 23

What is the trend in reactivities of the halogens?

Answer 23

The reactivity decreases down the group as each element has an extra shell of electrons so the outermost electron is further away and experiences a weaker nuclear attraction.

Question 24

What colours will water and cyclohexane be when one halogen displaces another?

Answer 24

Water:
-Chlorine = pale green
-Bromine = orange
-Iodine = brown
cyclohexane
-Chlorine = pale green
-Bromine = orange
-Iodine = violet

Question 25

What is disproportionation?

Answer 25

The oxidation and reduction of the same element in a redox reaction.

Question 26

How do you test for carbonate ions?

Answer 26

Add a strong dilute acid, collect gas formed and pass it through limewater. I the limewater turns cloudy, carbonate ions are present.

Question 27

How do you test for sulfate ions?

Answer 27

Add dilute hydrochloric acid and barium chloride and a white precipitate of barium sulfate will be produced id sulfate ions are present.

Question 28

How do you test for halide ions?

Answer 28

Dissolve the halide in water, add aqueous silver nitrate and a precipitate will be formed if halide ions are present.

chloride: white
bromide: cream
iodide: yellow

Question 29

How do you test for ammonium ions?

Answer 29

Add sodium hydroxide solution and warm gently. Test gas with red litmus paper, if the paper turns blue, ammonium ions are present.