Topic 1.

Question 1

What is an element?

Answer 1

An element is a substance containing one type of atom with all atoms in an element having the same proton number.

Question 2

What is an atom?

Answer 2

An atom is the smallest part of an element that can take part in a chemical change.

Question 3

What is a proton?

What is the mass of a proton?

What is the charge of a proton?

Answer 3

A proton is a poisitively charged particle in the nucleus of an atom.

1.

+1.

Question 4

What is an electron?

What is the mass of a electron?

What is the charge of a electron?

Answer 4

An electron is a negatively charged particle found in the orbitals outside the nucleus of an atom with a negligible mass compared with a proton.

1/1836.

-1.

Question 5

What is a neutron?

What is the mass of a neutron?

What is the charge of a neutron?

Answer 5

A neutron is an uncharged particle in the nucleus of an atom with the same relative mass of a proton.

1.

0.

Question 6

What are isotopes?

Answer 6

Atoms of the same element with the same number of protons but a different number of neutrons

Question 7

What is first ionisation energy?

Answer 7

First ionisation energy is the energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous 1+ ions.

Question 8

What factors affect ionisation energy?

Answer 8

• Nuclear charge.
• Atomic radius.
• Electron shielding.
• Spin-pair repulsion.

Question 9

What is atomic radius?

Answer 9

Atomic radius is the total distance from an atom’s nucleus to the outermost orbital of electron.

Question 10

Explain the electron shielding effect.

Answer 10

The electron shielding effect is one that the inner electrons reduce the pull on the nucleus on the electrons in the outer shell.

Question 11

Explain nuclear charge.

Answer 11

Nuclear charge is a measure of how positive the nucleus is .
The higher the proton or atomic number of an element, the more protons it has in its nucleus, and, hence the higher the nuclear charge.

Question 12

How does nuclear charge affect ionisation energy?

Answer 12

More protons in the nucleus means a greater nuclear charge and a stronger attraction to the outer shell electrons so first ionisation energy is greater.

Question 13

How does atomic radius affect ionisation energy?

Answer 13

A larger atomic radius means weaker attractive forces between the positive nucleus and negative electrons so first ionisation number is lower.

Question 14

How does electron shielding affect ionisation energy?

Answer 14

More electron shells means more electron shielding so there is weaker attraction between outershell electrons and the nucleus so first ionisation energy is lower.

Question 15

How does spin-pair repulsion affect ionisation energy?

Answer 15

When electrons are paired in an orbital, there is an electron pair repulsion which causes the energy of the electrons to increase. Increased energy makes the electron easier to remove and therefore the ionisation energy decreases.

Question 16

What happens to first ionisation energy across a period?

Answer 16

The first ionisation energy of elements increases across a period. This is because although electron shielding remains the same, nuclear charge increases which draws the outer shell electrons inwards causing a slight decrease in atomic radius. This means more energy is required to remove an outer shell electron as it is attracted more strongly to the nucleus.

Question 17

What happens to first ionisation energy down a group?

Answer 17

The first ionisation energy decreases down a group because although nuclear charge increases, atomic radius and electron shielding also increase meaning less energy is required to remove an outer shell electron.

Question 18

Why is there a large decrease in ionisation energy between the last element in one period and the first element in the next period?

Answer 18

This is because there is increased distance between the nucleus and the outer shell electrons as you add a new shell. There is increased shielding by inner electrons because of added shells. These two factors outweigh increased nuclear charge.

Question 19

What is successive ionisation energy?

Answer 19

Successive ionisation energies involve removing one mole of electrons from one mole of gaseous ions.

Question 20

What are the first, second and third ionisation energy of aluminium?

Answer 20

Al (g) → Al⁺ (g) + e
Al⁺ → Al²⁺ (g) + e
Al²⁺ → Al3⁺ (g) + e

Question 21

What does a large jump between successive ionisation energies indicate?

Answer 21

A large jump between successive ionisatio energies indicate which group an element is in.