C3 halogens

Question 1

Colour and state at RTP
F
Cl
Br 
I

Answer 1

F) yellow, solid
Cl) green, solid
Br) red/brown, liquid
I) grey, liquid

Question 2

Trend of boiling point

and why?

Answer 2

Boiling point increases as you go down the group
=> increased size makes induced dipole-dipole interactions increase
=> more energy is needed to separate the molecules

Question 3

Trend of electronegativity

and why?

Answer 3

Electronegativity decreases as you go down the group

=> increasing nuclear charge due to the greater number of protons, this should attract electrons more
However,
=> increasing number of shells: more shielding and less pull on electrons
=> increasing atomic radius: attraction drops off as distance increases