Open Question
How many electrons are present in an atom in which the first and second shells and the 3s subshell are filled? Name the element.
9. Electrons in Atoms and the Periodic Table
Electron Arrangements
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Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
Write the electron arrangement for the following element:Calcium (Z = 20)
A
2-2-6-2-6-2
B
2-8-8-2
C
2-16-2
D
2-8-8-1
E
1-2-2-8-2
Verified step by step guidance1
Identify the atomic number of Calcium, which is 20. This indicates the number of electrons in a neutral atom of Calcium.
Understand that electrons are arranged in energy levels or shells around the nucleus. The maximum number of electrons that can be held in each shell is determined by the formula 2n^2, where n is the shell number.
Start filling the electrons into the shells beginning with the lowest energy level (n=1) and move to higher levels. The first shell can hold up to 2 electrons, the second up to 8, the third up to 18, and so on.
Distribute the 20 electrons of Calcium: Fill the first shell with 2 electrons, the second shell with 8 electrons, and the third shell with 8 electrons. The remaining 2 electrons go into the fourth shell.
Verify the electron configuration: The electron arrangement for Calcium should be 2-8-8-2, which corresponds to the distribution of electrons across the shells.
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