Electron Distribution in Shells
Electron distribution in shells means arranging electrons in fixed shells around the nucleus according to their maximum capacity and filling order.
Practice This ConceptMain explanation
Teacher explanation
In the Bohr-Bury scheme, shells are filled from inner to outer levels. The maximum number of electrons in a shell is given by 2n², where n is the shell number. K shell can hold 2, L shell can hold 8, and M shell can hold 18, but for the first 20 elements, students usually fill as 2, 8, 8 before moving further.
Example
Magnesium has 12 electrons, so its distribution is 2, 8, 2.
Simple analogy
Fill from home outward: K before L before M.
Common confusion
Students often put more than 2 electrons in the K shell or fill outer shells before inner shells.
Exam tip
For the first 20 elements, fill K first, then L, then M using 2, 8, 8 as the practical pattern.
Study the electron distribution in shells diagram carefully
Use the labelled diagram to keep electron distribution in shells clear in short answers and revision.
What this diagram makes clear
This diagram keeps the labels and direction of electron distribution in shells in the right order.
Where this helps in exams
Use this for labelled diagram work and short exam answers on electron distribution in shells.
Revision cue
Revise electron distribution in shells through the labels before writing the answer.
Answer writing and exam use
1-mark use
Write the exact meaning of electron distribution in shells in one clean line.
2-mark use
Define electron distribution in shells and add one example or condition.
3-mark use
Explain electron distribution in shells, show the method or example, and mention the common mistake.
Practice this concept with focused MCQs
Open the concept quiz intro first, review the test details, and then start a focused MCQ set from this concept only. Instant score and answer review are live now.
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