Question

What is the correct order of elements according to their valence shell electrons?

• A. Ne>N> F > Be
• B. F>O>C>Li
• C. Li>O>C>F
• D. B>C>O>F

Answer 1

Answer:

B. F>O>C>Li

The correct order of elements according to their valence shell electrons is F > O > C > Li.

The number of valence electrons (electrons in the outermost shell) of an element corresponds directly to its main group number on the periodic table:

• Fluorine (F): Belongs to Group 17 $\rightarrow$ 7 valence electrons

• Oxygen (O): Belongs to Group 16 $\rightarrow$ 6 valence electrons

• Carbon (C): Belongs to Group 14 $\rightarrow$ 4 valence electrons

• Lithium (Li): Belongs to Group 1 $\rightarrow$ 1 valence electron

Arranging them in a strictly decreasing sequence gives:
\mathbf{7 > 6 > 4 > 1}
\mathbf{F > O > C > Li}

Why the other options are incorrect:

• Ne > N > F > Be: Incorrect because Neon (8) > Nitrogen (5) > Fluorine (7) > Beryllium (2) is out of logical sequence since 5 is not greater than 7.

• Li > O > C > F: Incorrect because it states Lithium (1) is greater than Oxygen (6).

• B > C > O > F: Incorrect because Boron (3) is less than Carbon (4), meaning the signs point in the wrong direction.