Groups and Trends

Melting and boiling points increase as you go down the group
7 electrons in the outer shell (group 7 duh)
gets darker in colour as you go down the group
all diatomic molecules

Chl

Chorine is a toxic gas that cannot be stored easily
- reacted with potassium manganate to produce potassium chloride which is then dissolved in water which separates some of the chloride ions into chlorine
overall product= 

halogens with iron wool

Most reactive: fluorine
Least reactive: iodine

Reactivity decreases as you go down the group

Fluorine is the most reactive because it has the least electrions

halogen: element in group 7
halide: compound of a halogen and another element

More reactive halogens replace halides