For metals:
- Reactivity increases as you go down a group, the further you go down, the easier the metals take or give electron
- Reactivity decreases as you go across, more energy required to get rid of valence electron
For non-metals:
- Reactivity increases as you go up a group. Electronegativity increases as you go higher up, more powerful exchange of electrons
- Relativity increases as you go across since the closer you get to fill up your s- and p- orbitals the more motivated you are to do so.