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Multiple Choice
A neutral atom has the following electron configuration: 1s^2 2s^2 2p^6 3s^2 3p^5. Which element is this atom?
A
Chlorine (Cl)
B
Sulfur (S)
C
Phosphorus (P)
D
Argon (Ar)
Verified step by step guidance
1
Identify the total number of electrons in the given electron configuration: $1s^2 2s^2 2p^6 3s^2 3p^5$. Add the superscripts to find the total electrons: $2 + 2 + 6 + 2 + 5$.
Since the atom is neutral, the number of electrons equals the atomic number (number of protons). Use the total electrons calculated to determine the atomic number.
Refer to the periodic table to find the element with the atomic number equal to the total electrons counted.
Recognize that the electron configuration ends in $3p^5$, which indicates the element is in the halogen group (Group 17) of the periodic table.
Match the atomic number and group to identify the element as Chlorine (Cl).