how valence electrons determine the kind and number of bonds formed by an element?
Dear Student,
Generally, If valence shell contains 1 to 3 electrons are most electromotive and lose electrons and form positive ions. So, they form ionic compounds.
If valence shell contains 4-7 electrons, they generally try to form covalent bond by sharing of electrons. If they contain 7 electrons in outermost shell, single bond is formed as in Cl2. If they contain 6 electrons in outermost shell, double bonds are formed as in O2. If they contain 5 electrons in outermost shell, triple bonds are formed as in N2.
If they contain 7 electrons in outermost shell, gain of one electron makes it negative ion. So, it can form ionic bond with the cation also as NaCl.