Electronegativity is a measure of how easy it is for an atom to attract another electron. the elements he, ne, and ar have the lowest electronegativity values. what do these elements have in common? 1. they have an outer orbital full of electrons. 2. they lose a proton which makes them negatively charged. 3. they have an extra electron which makes them positively charged. 4. they have one electron in their outer orbital.

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-