2.1 periodicity

Question 1

what happens to atomic radius across a period?

Answer 1

decreases as proton number increases so electrons pulled closer to nucleus so radius smaller

Question 2

what happens to melting point across group 3?

Answer 2

generally increases from sodium to silicon then generally decreases from silicon to argon

Question 3

why does melting point increase from sodium to aluminium?

Answer 3

they are metals so mp increases across group as metallic bonds get stronger due to increased nuclear charge and delocalised electrons

Question 4

why is there a big increase in melting point from aluminium to silicon?

Answer 4

silicon is macromolecular and has a tetrahedral shape- lots of strong covalent bonds to break

Question 5

what happens to first ionisation energy across period 3?

Answer 5

general increase as you go across as there is increasing attraction between outer shell electrons and nucleus due to proton number increasing

Question 5

what happens to melting point between phosphorus, sulphur, chlorine and argon?

Answer 5

phosphorus, sulphur and chlorine are all molecular substances. their melting points depend on vdw forces- weak so easily overcome. more atoms in molecule means more vdw. sulphur is biggest so has highest mp. argon very low as it is monoatomic so very weak vdw