Question

An atom with a total of _______ electrons is most likely to become an anion.

10

9

11

7

Answer 1

the total number of electrons present in an atom is equal to its atomic number.

Hence an atom with 10 electrons corresponds to the inert gas Ne that has stable inert gas configuration.

Since Ne has stable inert gas configuration, it will lose electron further. Hwever other atoms nearer to Ne atom will either lose or gain electron to attain stable inert gas configuration of Ne

Ne(10) : 1s2 1s2 2p6

Similarly an atom with 9 electrons corresopnds to F atom.

F(9): 1s2 1s2 2p5

Here F atom requires 1 electron to attain the stable inert gas configuration of Ne aton.

Hence F atom will gain 1 electron by forming an anion to attain the nearest stable inert gas configuration of Ne

F + 1e- -------> F^-   (anion)

F^-(10 electrons) : 1s2 1s2 2p6 (stable inert gas configuration)

Hence second option (9) is the correct answer.

Also an atom with 11 electrons corresponds to Na atom.

Na(11): 1s2 1s2 2p6 3s1

Here Na atom has 1 extra electron in comparisn to Ne and to gain the inert gas conf. of Ne it will lose 1 eectron to form a cation

Na ------> Na⁺ (cation) + 1e-

an atom with 7 electron will correspond to N. Since N has stable half filled p - orbital configureation(p3) it is also less likely to form an anion in comparison to F

N(7) : 1s2 1s2 2p3 (stable half filled p - orbital configureation)

Hence second option, 9(F) is the correct answer.

F + 1e- -------> F^-   (anion)