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28 Dec 2025

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2 pages

Understanding Atomic Orbitals in Chemistry

anna🦋🧬📓🔬

@biannnl

Understanding where electrons live around an atom's nucleus isn't as... Show more

1st
2nd
3rd
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Shell
ATOMIC
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• Each shell lenergy level) is given a number
Scientists call this the principal quantum number or

Electron Shells and the Principal Quantum Number

Remember from GCSE that electrons exist in electron shells around the nucleus? Well, scientists give each shell a number called the principal quantum number, written as "n". The first shell is n=1, the second is n=2, and so on.

Here's the brilliant bit: you can calculate the maximum number of electrons any shell can hold using the formula 2n². So shell 1 holds 2×1² = 2 electrons, shell 2 holds 2×2² = 8 electrons, shell 3 holds 18, and shell 4 holds 32 electrons.

But here's where it gets interesting - electrons aren't just floating around randomly in these shells. They occupy specific regions called atomic orbitals. Think of an atomic orbital as a 3D space around the nucleus where you're likely to find up to two electrons.

Key Point: Each orbital can hold a maximum of two electrons, but they must have opposite spins - one "up" and one "down".

The electrons behave like clouds of negative charge, and these clouds take on the actual shape of the orbital they're occupying. There are four main types of orbitals, each with its own letter: s, p, d, and f.

Types of Atomic Orbitals: s, p, d, and f

S orbitals are the simplest - they're perfectly spherical, like a ball around the nucleus. Every single electron shell contains exactly one s orbital.

P orbitals look completely different - they're shaped like dumbbells or figure-8s. There are always three p orbitals in each shell, except for the first shell which doesn't have any p orbitals at all.

D orbitals are more complex, with five different d orbitals appearing in shell 3 and above. F orbitals are the most complicated, with seven different f orbitals that only show up in shell 4 and higher.

Remember: A subshell is just all the orbitals of the same type in one shell - like "2p" (all three p orbitals in shell 2) or "3d" (all five d orbitals in shell 3).

This explains why electron capacity jumps so dramatically as you move outward from the nucleus. Shell 1 only has an s orbital (2 electrons max), but shell 4 has s, p, d, and f orbitals, giving it space for 32 electrons total.

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28 Dec 2025

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2 pages

Understanding Atomic Orbitals in Chemistry

anna🦋🧬📓🔬

@biannnl

Understanding where electrons live around an atom's nucleus isn't as simple as GCSE chemistry suggested. At A-level, you'll discover that electron shells are actually made up of different shaped regions called atomic orbitals, and there's a clever formula to work... Show more

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Electron Shells and the Principal Quantum Number

Key Point: Each orbital can hold a maximum of two electrons, but they must have opposite spins - one "up" and one "down".

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Types of Atomic Orbitals: s, p, d, and f

S orbitals are the simplest - they're perfectly spherical, like a ball around the nucleus. Every single electron shell contains exactly one s orbital.

Remember: A subshell is just all the orbitals of the same type in one shell - like "2p" (all three p orbitals in shell 2) or "3d" (all five d orbitals in shell 3).