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The Periodic Table

Group 7 - The Halogens - Group Trends.

What are the Group Trends for the Halogens?

As you go down group 7 from fluorine to astatine, the halogens

1. Have higher melting points and boiling points.

2. Have a higher density.

3. Are bad conductors of heat and electricity.

4. Have bigger atoms. Each successive element in the
next period down has an extra electron shell. It is the
electron shells which take up nearly all the space of an atom.

5. Are less reactive. Fluorine is the most reactive, astatine the least.
As the size of the atoms increase, the extra outer electron
(which it wants to gain or share to become a stable ion or molecule)
is further and further from the positive nucleus. It is the attraction
between the negative incoming electron and the positive nucleus
that determines how easily the electron will be gained.

The smaller the atom, the closer the incoming outer electron is,
the more attracted it is, and the more reactive the halogen is.

Also, the smaller the atom, the less shielding there is.

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