Group 7

The Halogens

• Halogens are found in group 7

Physical Properties

• Chlorine - green gas
• Bromine - heavy red gas
• Iodine - Produces a purple gas

Diatomic Molecules

• Diatomic - consisting of two type of the same atoms
• Halogens are diatomic as they need one electron to form a full shell
• Hydrogen, oxygen and nitrogen are diatomic too
• Halogens have low melting point because of weak intermolecular forces between the molecules

Decreasing Reactivity

• As you go down group 7 in the periodic table, the reactivity of the halogens decrease
• This is because the atoms become larger with more electron shells
• The increased distance reduces the attraction of the nucleus on the incoming electron, making it harder for the halogens to gain an electron and react
• In addition, the more shells of electrons the more shielding there is which decreases the attraction from the nucleus to the electrons