what keeps an identical atoms of an element together? I have learned that the atoms of different elements are held together by covalent bonding and ionic bonding but in the case same element which force keeps the atoms together i.e in  sodium which is the force that keep sodium atoms in position?which is the force acting between the atoms of sodium?
well atoms of the same element will typically either, forma metallic lattice, a giant covalent structure ( a macro-molecule), or from a simple molecular structure. but all the bonds will either be metallic or covalent bonds. if it forms a simple covalent structure, there will be van der Waal's forces acting between the molecules to keep it as a solid or liquid.