The Halogens

* The halogens can be found on the left-hand side of the noble gases. * These five toxic, non-metallic elements make up Group 17 of the periodic table and consist of: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). * Although astatine is radioactive and only has short-lived isotopes, it behaves similar to iodine and is often included in the halogen group. * Since the halogen elements have seven valence electrons, they only require one additional electron to form a full octet. This characteristic makes them more reactive than other non-metal groups. * More electrons= stronger intermolecular forces as instantaneous induced dipole-dipole forces are greater. * The more electrons you have, the stronger these forces are, so less volatile down the group as electrons increase. * Ok, volitility decreases down the halogen group.
This is because
- each successive element has more electrons, which are added to new shells furthur away from the nucleus..
- They are thus less tightly attracted by the buclear charge - protons.
- Thus they oscillate with greater magnitude and frequency, inducing oscillations in adjcent atoms.
- This averages out to weak attractive forces
- As oscillations increase in magnitude and frequency down the group, the wan der waals attraction force becomes stronger.
- Thus more engergy to reak / higher Ea.
- Hence less likely to react/less volatile. * As you go down the group, halogens become less volatile, as their shell size increases. This increases the VDW forces as there are more electrons, hence increasing the force of attraction between molecules. This makes them less