How is electronegativity related to covalent bonding?

For ai it's atomic number is 13 and it's mass number is 27 how many neutrons does it have

The name of the ion, s2-, is: sulfurous ion sulfide ion sulfur ion sulfate ion

Me i dont know what to do! the table compares the number of electrons in two unknown neutral atoms. comparison of electrons atom number of electrons a 10 d 11 use this information to determine the number of valence electrons in the atoms. which of the following correctly compares the stability of the two atoms? both are unreactive. both are highly reactive. a is unreactive and d is reactive. a is reactive and d is unreactive.