Shells are labelled by n and contain subshells s, p, d and f with 1, 3, 5 and 7 orbitals respectively.
Practise Atomic Structure & Periodicity All Atomic Structure & Periodicity topics
Electrons are organised into shells labelled by the principal quantum number n, and each shell contains subshells labelled s, p, d and f. These subshells hold 2, 6, 10 and 14 electrons respectively, because they contain 1, 3, 5 and 7 orbitals that each hold two electrons. The shell structure explains the lengths of the periods in the periodic table, which are 2, 8, 8, 18, 18 and 32 elements. Subshells are filled in a predictable order that determines the ground-state configuration of each element. This concept underpins chemical bonding and periodic trends.
Key ideas: A shell is all orbitals of one n; subshells are the sets with the same n and l. Capacity: s 2, p 6, d 10, f 14 electrons. Notation: 3d7 means n = 3, l = 2, with 7 electrons. Total in shell n is 2 n^2, but outer shells fill only up to 8 or 18 in practice because of subshell ordering.
Common mistakes and connections: Students write 2d or 1p, or think the third shell always holds 18 before the fourth starts, but 4s fills before 3d. Shell labels K, L, M relate to X-ray spectra. This leads to the Aufbau principle and the structure of the periodic table's blocks.
Shell capacity is 2n^2: the first four shells hold 2, 8, 18 and 32 electrons across their s, p, d and f subshells. The interactive lesson shows this as a live animation or chart.
The second shell has a 2s subshell with 2 electrons and a 2p subshell with 6 electrons, for a total of 8.
Shells are labelled by n and contain subshells s, p, d and f with 1, 3, 5 and 7 orbitals respectively.
Electron Shells and Subshells is a beginner topic in Atomic Structure & Periodicity. It needs no earlier chemistry lessons and is a good starting point.
Study these earlier topics in Atomic Structure & Periodicity first: Shapes of s and p Orbitals, Shapes of d and f Orbitals, Radial and Angular Nodes.
The next topics in Atomic Structure & Periodicity are Aufbau Principle and Pauli Exclusion Principle.
Yes. The interactive lesson includes a self-check question on Electron Shells and Subshells, and the Atomic Structure & Periodicity quiz draws on every topic in this area.
Electron Shells and Subshells is topic 60 of 115 in Atomic Structure & Periodicity.