Flexi Says: Group I of the periodic table consists of hydrogen and alkali metals. In each case, there is one electron in the outer orbital, an s-orbital electron. Hydrogen is not an alkali metal but has some similar properties due to its simple one proton (located in the nucleus) and one electron arrangement. The lone electron exists in an s-orbital around the nucleus. There are two 1s electrons in an inner orbit for lithium and one 2s electron in the outer orbit. The same pattern holds for sodium and potassium.
