Answer:
Group 2 elements are berylium, magnesium, calcium, scrotium, barium and radium. These elements are called alkali earth metals and are divalent elements because they have two valence electrons that is they have two electrons in their outermost shell and also ionize by donating their two valence electrons.
They are most similar as they are all reducing agents and they form electrovalent compounds when combined with other elements.
They react with water  differently. Berylium does not react with cold water or steam, magnesium reacts with only steam while calcium reacts slowly with cold water, they liberate hydrogen gas and magnesium oxide and calcium hydroxide respectively.
Based on the number of protons and neutrons these elements have, the number of proton which is the same as the number of electron increases by 8 from berylium to magnesium and then to calcium and then by 18 from calcium to scrotium and barium while 32 from barium to radium.
