Atomic Structure
Atomic structure explores the composition of atoms including subatomic particles, electron configurations, quantum numbers, and atomic orbitals. Foundation for understanding chemical behavior.
Key Concepts
Study Tips
- ✓Electron configuration follows: 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f...
- ✓Each orbital holds maximum 2 electrons with opposite spins
- ✓Hund's Rule: fill orbitals singly first, then pair up
- ✓Noble gas shorthand: [Ar] 4s2 3d10 4p5 for Br
Common Mistakes to Avoid
Common errors include forgetting that 4s fills before 3d but empties first for transition metal ions, misapplying Hund's rule (electrons spread out in same-energy orbitals), and confusing quantum number allowed values. Remember exceptions: Cr is [Ar]4s1 3d5, Cu is [Ar]4s1 3d10.
Atomic Structure FAQs
Common questions about atomic structure
n (principal): energy level, 1,2,3... l (angular): orbital shape, 0 to n-1 (s,p,d,f). ml (magnetic): orbital orientation, -l to +l. ms (spin): electron spin, +1/2 or -1/2. Together they uniquely identify each electron.
Cr is [Ar]4s1 3d5 and Cu is [Ar]4s1 3d10 because half-filled and fully-filled d subshells are extra stable. The energy gain from this stability outweighs the normal filling order. This explains their unique chemistry.
Remove electrons from the highest n value first, regardless of filling order. For Fe2+, remove 2 electrons from 4s before 3d: Fe is [Ar]4s2 3d6, Fe2+ is [Ar]3d6. This is because 4s is higher energy for transition metal ions.