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Multiple Choice
Which element has the electron configuration 1s^2 2s^2 2p^6 3s^2 3p^6 4s^1?
A
Sodium (Na)
B
Calcium (Ca)
C
Potassium (K)
D
Magnesium (Mg)
Verified step by step guidance
1
Understand that the electron configuration given is 1s^2 2s^2 2p^6 3s^2 3p^6 4s^1, which describes the distribution of electrons in the atomic orbitals of an element.
Count the total number of electrons by adding the superscripts: 2 (1s) + 2 (2s) + 6 (2p) + 2 (3s) + 6 (3p) + 1 (4s) = 19 electrons.
Recall that the number of electrons in a neutral atom equals the atomic number of the element, so this element has atomic number 19.
Use the periodic table to identify the element with atomic number 19, which is Potassium (K).
Confirm that the electron configuration matches the expected configuration for Potassium, which ends in 4s^1, indicating one electron in the 4s orbital.