Periodic table

Thank you

I. Density and Melting Point of Alkali Metals.

Density of alkali metals increase as it goes down the periodic table. This is because as atomic number increase, there is more proton and neutron in the nucleus. Hence, the atomic mass is greater, and since density equals to mass over volume, density increases as it goes down the periodic table.

As it goes down the periodic table, the distance between the valence electron and nucleus increases, so the atom is more likely to lose its valence electron to obtain full outer shell. Hence, the atom becomes less reactive, having lower melting point.

II. Oxides.

You just have to know that metal oxides are basic and non-metal oxides are acidic.