Period 3

Question 1

What is the general trend down a group?

Answer 1

• Increase in atomic number- Increase in shielding- Increase in atomic radius- Decrease in effective nuclear charge- Decrease in 1st ionisation energy- Decrease in electronegativity

Question 2

What is the general trend across a period?

Answer 2

• Increase in atomic number- Shielding remains the same- Decrease in atomic radius- Increase in effective nuclear charge- Increase in 1st ionisation energy- Increase in electronegativity

Question 3

What happens to atomic radius as you go across period 3 and why?

Answer 3

Atomic radius decreases because - increase in nuclear charge- same shielding- electrons drawn closer to the nucleus, decreasing radius

Question 4

What happens to first ionisation energy as you go across period 3 and why?

Answer 4

First ionisation energy increases - increase in nuclear charge- same shielding - greater attraction of outer electrons to nucleus therefore more energy needed to remove an outer electron (Mg to Al and P to S are exceptions because of orbitals)

Question 5

What happens to melting and boiling point as you go across period 3 and why?

Answer 5

• Slow increase from Na to Al because of there metallic bonding. It increases with increased charge on the positive ions because there are stronger electrostatic attractions - Giant spike to Si because it is a giant covalent structure, very high because strong covalent bonds need to be broken- Small decrease to P4, small increase to S8 and gradual decrease to Ar because induced dipole forces only and the trend will vary based on size of the molecule because size of ID forces is directly linked to Mr (no. of electrons involved in I.D.)