Multiple Choice
1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 is the electron configuration for which element?
10. Periodic Properties of the Elements
The Electron Configuration
Multiple Choice
Which element has an electron configuration of 2–5, and how many protons does its atom contain?
A
2
B
12
C
7
D
5
Verified step by step guidance1
Understand that the electron configuration given, 2–5, means the element has 2 electrons in the first shell and 5 electrons in the second shell.
Recall that the total number of electrons in a neutral atom equals the number of protons in the nucleus.
Add the electrons in all shells to find the total number of electrons: 2 + 5 = 7 electrons.
Identify the element with 7 protons (and thus 7 electrons) by referring to the periodic table; this element is nitrogen (N).
Conclude that the element with electron configuration 2–5 is nitrogen, and it contains 7 protons.
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