Question

In the reaction between magnesium and sulfur, the magnesium atoms

Answer 1

Answer: Option (b) is the correct answer.

Explanation:

Atomic number of magnesium is 12 and its electronic distribution is 2, 8, 2. Whereas atomic number of sulfur is 16 and its electronic distribution is 2, 8, 6.

So, in order to attain stability a magnesium atom needs to lose its 2 valence electrons and a sulfur atom needs to gain two electrons to completely fill its octet.

Hence, magnesium on losing two electrons will acquire a +2 charge and thus, it becomes a cation. On the other hand, sulfur on gaining two electrons will acquire a -2 charge and thus, sulfur will become an anion.

Thus, we can conclude that in the reaction between magnesium and sulfur, the magnesium atoms become cations.

Answer 2

Answer: b. become cations

Explanation:

$Mg+S\rightarrow MgS$

For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.

In $MgS$, magnesium is having an oxidation state of +2 called as $Mg^{2+}$ cation and sulphur is having an oxidation state of  -2 called as $S^{2-}$ anion.

Electronic configuration of magnesium:

$[Mg]=1s^22s^22p^63s^2$

Magnesium atom will loose two electrons to gain noble gas configuration and form $Mg^{2+}$

$[Mg^{2+}]=1s^22s^22p^63s^0$

Electronic configuration of sulphur

$[S]=1s^22s^22p^63s^23p^4$

Sulphur atom will gain one electron to gain noble gas configuration and form sulphide ion with -2 charge.

$[S^{2-}]=1s^22s^22p^63s^23p^6$

Thus In the reaction between magnesium and sulfur, the magnesium atoms become cations.