 The beryllium atom has the electronic configuration [ He ] 2s2 . The two valence electrons give beryllium a + 2 oxidation state and thus the ability to form two covalent bonds ; the only evidence of lower valence of beryllium is in the solubility of the metal in BeCl2 . Due to the octet rule , atoms tend to seek a valence of 8 in order to resemble a noble gas . Beryllium tries to achieve a coordination number of 4 because its two covalent bonds fill half of this octet . A coordination of 4 allows beryllium compounds , such as the fluoride or chloride , to form polymers . 
