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Multiple Choice
How many valence electrons are present in a neutral atom of phosphorus (P)?
A
8
B
3
C
5
D
7
Verified step by step guidance
1
Identify the element in question, which is phosphorus (P).
Determine the atomic number of phosphorus, which is 15, meaning it has 15 electrons in a neutral atom.
Write the electron configuration of phosphorus to understand the distribution of electrons in its shells: $1s^2 2s^2 2p^6 3s^2 3p^3$.
Recognize that valence electrons are the electrons in the outermost shell (highest principal quantum number). For phosphorus, the outermost shell is the third shell (3s and 3p orbitals).
Count the electrons in the 3s and 3p orbitals: $3s^2$ means 2 electrons and $3p^3$ means 3 electrons, so total valence electrons = 2 + 3 = 5.