Practice Electron Shell in Chemistry

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

Quick Recap

A discrete energy level surrounding the atomic nucleus where electrons reside, with each shell (n = 1, 2, 3, ...) holding a maximum of 2n^2 electrons. Lower shells have less energy and fill first.

Electrons live in 'floors' around the nucleus. Lower floors fill first.

Example 1

easy
How many electrons can each of the first three electron shells hold? Show the maximum capacity for shells n = 1, n = 2, and n = 3.

Example 2

medium
Draw the electron shell diagram (Bohr model) for a sodium atom (Z = 11). How many electrons are in each shell?

Example 3

medium
Draw the electron shell diagram for sodium (Na, Z=11). How many electrons are in each shell?

Example 4

medium
Determine the electron shell arrangement for chlorine (Z = 17). How many electrons are in the outermost shell, and what does this predict about chlorine's chemical behavior?

Example 5

hard
Compare the electron shell arrangements of neon (Z = 10) and argon (Z = 18). Explain why both are chemically inert despite having different numbers of total electrons.
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