Multiple Choice
How many valence electrons does the element helium (He) have?
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10. Periodic Properties of the Elements
Valence Electrons of Elements
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Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
How many p electrons are present in a neutral atom of selenium (Se)?
A
6
B
18
C
12
D
16
Verified step by step guidance1
Identify the atomic number of selenium (Se), which tells you the total number of electrons in a neutral atom. Selenium has an atomic number of 34, so it has 34 electrons.
Recall the electron configuration order and fill the orbitals according to the Aufbau principle: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, etc.
Determine how many electrons occupy the p orbitals by looking at the electron configuration of selenium. The p orbitals start filling at the 2p level and include 2p, 3p, and 4p orbitals for selenium.
Count the electrons in all the p subshells: 2p, 3p, and 4p. Each p subshell can hold a maximum of 6 electrons, so add the electrons in these subshells to find the total number of p electrons.
Sum the electrons in the 2p, 3p, and 4p orbitals to get the total number of p electrons in selenium.
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