Answer to Question #117224 in Chemistry for sean

Question

The atomic number of element Q is 24
a)write the electronic configuration of the oxide of Q
b) write the formular of the oxide of Q
c)state whether the oxide of Q you have given in b) is basic or amphoteric. Write an equation to illustrate your answer

Answer 1

According to the atomic number 24, the element Q is chromium Cr.

a) You must have meant the electronic configuration of the element. The electronic configuration of the element is [Ar]3d⁵4s¹, or 1s²2s²2p⁶3s²3p⁶3d⁵4s¹.

b) Chromium can exist in different oxidation states. Therefore, different oxides exist:

CrO (oxidation number of Cr +2), Cr₂O₃ (+3), CrO₂ (+4), CrO₃ (+6) and CrO₅ (peroxide, +6). CrO₂ is insoluble in water. CrO₅ is unstable. The electronic configurations of chromium in its most important oxides are:

CrO : [Ar]3d⁴

Cr₂O₃: [Ar]3d³

CrO₃: [Ar]3d⁰.

c) The CrO oxide is basic, Cr₂O₃ is amphoteric, CrO₃ is acidic. Indeed, CrO reacts with chloric acid with the release of hydrogen:

CrO + 2HCl → CrCl₂ + H₂↑ .

Cr₂O₃ is amphoteric, because it reacts with bases with formation of chromites, and with acids with formation of chromium (+3) salt:

Cr₂O₃ + 2NaOH→ 2NaCrO₂ + H₂O

Cr₂O₃ + 6HCl → 2CrCl₃ + 3H₂O.

CrO₃ is acidic. It forms chromic acid with water and chromates with bases:

CrO₃ + H₂O→ HCrO₄

CrO₃ + 2NaOH → Na₂CrO₄ + H₂O.