Electron Shell Chemistry Example 2

Follow the full solution, then compare it with the other examples linked below.

Example 2

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

Solution

  1. 1
    Sodium has 11 electrons. Fill shells in order: shell 1 holds a maximum of 2, shell 2 holds a maximum of 8.
  2. 2
    Shell 1: 2 electrons. Shell 2: 8 electrons. Remaining: 11−2−8=111 - 2 - 8 = 1 electron.
  3. 3
    Shell 3: 1 electron. This single outer-shell electron explains why sodium easily forms Na+\text{Na}^+ by losing one electron.

Answer

Na: 2, 8, 1\text{Na: 2, 8, 1}
The Bohr model represents electrons in concentric shells around the nucleus. Sodium's single valence electron in the outermost shell makes it highly reactive — it readily loses this electron to achieve a stable octet in shell 2.

About Electron Shell

A discrete energy level surrounding the atomic nucleus where electrons reside, with each shell (n=1,2,3,...n = 1, 2, 3, ...) holding a maximum of 2n22n^2.

Learn more about Electron Shell →

More Electron Shell Examples

Example 1 easy

How many electrons can each of the first three electron shells hold? Show the maximum capacity for s

Example 3 medium

Draw the electron shell diagram for sodium (Na, [formula]). How many electrons are in each shell?

Example 4 medium

Determine the electron shell arrangement for chlorine ([formula]). How many electrons are in the out

Example 5 hard

Compare the electron shell arrangements of neon ([formula]) and argon ([formula]). Explain why both

← All Electron Shell Examples Electron Shell Concept