Question

based on the trend in valence electrons across periods for main - group elements, how many valence electrons does fluorine (f) have? a. 7 b. 4 c. 5 d. 6

Explanation:

Step1: Recall the group number - valence electron relationship

For main - group elements, the group number (using the 1 - 18 group numbering system, for groups 1 - 2 and 13 - 18, the number of valence electrons is equal to the group number minus 10 for groups 13 - 18 and group number for groups 1 - 2). Fluorine (F) is in group 17.

Step2: Calculate the number of valence electrons

Using the formula for groups 13 - 18 (valence electrons = group number - 10), for group 17, valence electrons \(=17 - 10=7\).

Answer:

A. 7