Question

element orbitals electron configuration 1s 2s 2p nitrogen (n) 1s²2s²2p³ fluorine (f) 1s²2s²2p⁵ carbon (c) 1s²2s²2p² which element has seven valence electrons? nitrogen (n) carbon (c) fluorine (f) none of the above

Explanation:

Step1: Identify valence - shell electrons

Valence electrons are the electrons in the outermost shell. For the given elements with electron - configurations in the second period, the outermost shell is the second shell (n = 2).

Step2: Calculate valence electrons for nitrogen (N)

Nitrogen has an electron - configuration of $1s^{2}2s^{2}2p^{3}$. The number of valence electrons is $2 + 3=5$.

Step3: Calculate valence electrons for carbon (C)

Carbon has an electron - configuration of $1s^{2}2s^{2}2p^{2}$. The number of valence electrons is $2 + 2 = 4$.

Step4: Calculate valence electrons for fluorine (F)

Fluorine has an electron - configuration of $1s^{2}2s^{2}2p^{5}$. The number of valence electrons is $2+5 = 7$.

Answer:

C. Fluorine (F)