Which of the following pairs of elements and valence electrons is incorrect?

Question

a
Al -3
b
Br - 7
c
Tl - 3
d
S - 4
e
Sr - 2

Answer 1

To determine which pair is incorrect, we need to review the typical number of valence electrons for each of the elements listed:

a. Al (Aluminum) - has 3 valence electrons. (Correct)

b. Br (Bromine) - has 7 valence electrons. (Correct)

c. Tl (Thallium) - has 3 valence electrons. (Correct)

d. S (Sulfur) - has 6 valence electrons, not 4. (Incorrect)

e. Sr (Strontium) - has 2 valence electrons. (Correct)

The incorrect pair is: d. S - 4 (Sulfur has 6 valence electrons, not 4.)