Lithium, Sodium and Potassium have following similarities:
(i) They all have valence electrons equal to 1 so they all belong to same group, i.e. Group 1st in Periodic Table.
(ii) They all are highly reactive and form ionic bonds with non-metals.
(iii) They all are highly electropositive..
(iv)All of these react with water to form alkalis.
Following properties are common in the atoms of Helium and Neon:
(i) Both have completely filled outermost orbit and have stable electronic configuration.
(ii) Both belong to the same group, i.e. zero group in Modern Periodic Table.