2) TRENDS IN THE PERIODIC TABLE

Question 1

What happens to atomic size as you go along a period and why?

Answer 1

Atom size decreases along a period

• This is because as you go across a period the nucleus becomes more positive
• The shells of electrons are more strongly attracted to the nucleus, making the atom smaller

Question 2

What happens to atomic size as you go down a group and why

Answer 2

Atomic size increases as you go down a group

• This is because there are more electrons shells
• The outer electron are also shielded from the full effect of the nucleus, (know as screening), so they are not pulled in closer therefore making the atom larger

Question 3

What is the first ionisation energy

Answer 3

The energy required to remove 1 mole of electrons from 1 mole of atom in a gaseous state

Question 4

What happens to ionisation energy as you go across a period and why

Answer 4

Along a period ionisation energy increases

• This is because along a period the nuclear charge increases making the atom smaller
• The outer electrons are closer to the nucleus so more strongly attracted
• Therefore the outer electron is more difficult to remove so ionisation energy increases

Question 5

What happens to ionisation energy as you go down a group and why?

Answer 5

Down a group ionisation energy decreases

• This is because as you go down a group there are more electron shells
• The outer electrons are further from the nucleus and are also shielded from the full effect of the nucleus
• Therefore the outer electron is easier to remove so ionisation energy decreases

Question 6

Why would there a massive increase in ionisation energy

Answer 6

The atom is stable and we are now trying to remove an electron from a stable inner electron

Question 7

What is electronegativity

Answer 7

The measure of attraction for electrons in a covalent bond

The higher the electronegativity of an element the stronger it’s attraction for electrons

Question 8

What happens to electronegativity as you go across a period

Answer 8

Along a period electronegativity increases

•This is because there is an increase in nuclear charge across periods which causes the atom to be strongly attracted to electrons

Question 9

What happens to electronegativity as you go down a group

Answer 9

Electronegativity decreases as you go down a period

• This is because as you go down groups the number of electron shells increases
• The outer electrons are further away from the nucleus and are shielded from the full effect of nucleus by inner electrons