Electron energy levels and sublevels
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Flip to reveal answersWhat is a main energy level (n)?
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Question
What is a main energy level (n)?
Answer
The major 'shell' of an atom (n = 1, 2, 3, …); higher n means **higher energy** and **further** from the nucleus.
Question
What is a sublevel?
Answer
A subdivision of a main level, labelled **s, p, d, f**, differing slightly in energy (s < p < d < f).
Question
What is an orbital?
Answer
A region around the nucleus that can hold up to **2 electrons**.
Question
Shape of an s orbital?
Answer
A **sphere** centred on the nucleus.
Question
Shape of a p orbital?
Answer
A **dumbbell** — two lobes pointing in opposite directions through the nucleus.
Question
How many orbitals in the s, p, d and f sublevels?
Answer
s = **1**, p = **3**, d = **5**, f = **7** orbitals.
Question
Maximum electrons in each sublevel?
Answer
s = **2**, p = **6**, d = **10**, f = **14** (2 electrons per orbital).
Question
Maximum electrons in main level n?
Answer
**2n²** — so n = 1 → 2, n = 2 → 8, n = 3 → 18, n = 4 → 32.
Question
Which fills first, 4s or 3d?
Answer
**4s** fills first — it is slightly lower in energy than 3d.
Question
What is Hund's rule (qualitatively)?
Answer
Electrons occupy orbitals of a sublevel **singly** (parallel spins) before any pairing up.
Question
Order of sublevel energies within a level?
Answer
**s < p < d < f** (s is lowest, f is highest).
Question
Sublevels in main level n = 3?
Answer
**3s, 3p and 3d** (max 18 electrons).
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