Question

page 5 of 5
you can use this periodic table during the quiz.
however, as stated in the course outline, and in
the orientation session, this quiz is not open book.
you cannot access course material while you write
the quiz. nor can you google your answers, work as
a group, use a cheat sheet, etc.
question 21 (1 point) ✓ saved
which of the following compounds demonstrates
an exception to the octet rule?
h₂o
c₂h₆
kcl
sf₆

Explanation:

Step1: Analyze \(H_2O\)

Oxygen has 6 valence electrons. Each hydrogen has 1 valence electron. In \(H_2O\), oxygen forms two single bonds with hydrogen. Oxygen has 8 valence electrons (2 lone pairs + 2 bonding pairs), and hydrogen has 2 valence electrons (duet rule, which is analogous to octet for hydrogen as it has only 1s orbital). So it follows the octet - like rules.

Step2: Analyze \(C_2H_6\)

Carbon has 4 valence electrons. In \(C_2H_6\), each carbon forms 3 single bonds with hydrogen and 1 single bond with the other carbon. Each carbon has 8 valence electrons (4 bonding pairs), and hydrogen has 2 valence electrons. It follows the octet - like rules.

Step3: Analyze \(KCl\)

Potassium donates its valence electron to chlorine. Potassium (after losing an electron) has a noble - gas configuration (\(Ar\) - like), and chlorine (after gaining an electron) has a noble - gas configuration (\(Ar\) - like). It follows the octet rule.

Step4: Analyze \(SF_6\)

Sulfur has 6 valence electrons. In \(SF_6\), sulfur forms 6 single bonds with fluorine. Sulfur has 12 valence electrons (\(6\) bonding pairs), which is an exception to the octet rule. Fluorine has 8 valence electrons (3 lone pairs + 1 bonding pair) for each \(F\) atom.

Answer:

\(SF_6\)