Notation describing total orbital angular momentum, spin and total angular momentum of an atomic state.
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A term symbol, written as 2S+1 L J, encodes the total spin S, total orbital angular momentum L and total angular momentum J of a multi-electron atomic state. The letters S, P, D and F stand for L values 0, 1, 2 and 3. The multiplicity 2S+1 gives the number of spin states, and J gives the fine-structure level. Hund's rules use these quantities to determine which term is the ground state. Term symbols label energy levels in atomic spectra.
Key ideas: A term symbol is written 2S+1 L J, where S is total spin, L is total orbital angular momentum (S, P, D, F for 0, 1, 2, 3), and J ranges from the absolute value of (L - S) up to L + S. Steps: place electrons in ml boxes by Hund's rule, sum ml for L and spins for S. Carbon 2p2 ground term is 3P0; the lowest J is for less-than-half-filled shells.
Common mistakes and connections: Students use the 2S+1 incorrectly (it is the multiplicity) and mix up the symbols L (capital) and l. Closed subshells contribute zero to L and S, so only partially filled subshells matter. Hund's three rules order terms: max S, then max L, then J. They underlie spectra, Zeeman splitting, and the magnetic properties of ions.
Carbon's 2p2 configuration gives the terms 3P (lowest, split by J), 1D and 1S, with Hund's rules fixing 3P as the ground term. The interactive lesson shows this as a live animation or chart.
Carbon's ground-state term is 3P0, a triplet P level with J = 0.
Notation describing total orbital angular momentum, spin and total angular momentum of an atomic state.
Term Symbols is a advanced topic in Atomic Structure & Periodicity. It builds on beginner and intermediate topics, so review those first if needed.
Study these earlier topics in Atomic Structure & Periodicity first: Island of Stability, Zeeman Effect, Stark Effect.
It is the last topic in Atomic Structure & Periodicity. Explore the other areas for more chemistry.
Yes. The interactive lesson includes a self-check question on Term Symbols, and the Atomic Structure & Periodicity quiz draws on every topic in this area.
Term Symbols is topic 115 of 115 in Atomic Structure & Periodicity.