Exceptions to the Octet Rule

Question 1

What are the three types of octet rule exceptions?

Answer 1

• Molecules with electron-deficient atoms
• Expanded valence shells
• Molecules with odd-electron atoms

Question 2

What are three examples of electron-deficient atoms?

Answer 2

Be, B, and Al

Question 3

Are molecules with electron-deficient atoms more or less reactive?

Answer 3

More reactive because they bond with compounds that have unshared electrons to give the electron-deficient central atom an octet.

Question 4

Which elements on the periodic table can have expanded octets?

Answer 4

Those in Period 3 and beyond (usually).

Question 5

What are free radicals?

Answer 5

A molecule or ion with an unpaired electron.

Question 6

On what type of molecules or ions do free radicals form?

Answer 6

Species with odd numbers of valence electrons.

Question 7

Are free radicals more or less reactive?

Answer 7

More reactive because they tend to lose their unpaired electron or gain other electrons.

Question 8

Are exceptions to the octet rule allowed in polyatomic ions?

Answer 8

Yes