Metallic — the electron sea

The third route: not share with one, not transfer to one, but pool among all. Every sodium atom gives its 3s electron to a sea that belongs to the whole crystal; what's left is a lattice of Na⁺ cations held together by their common attraction to the delocalized electrons flooding between them. The same 3s electron that went to one chlorine in NaCl here goes to everyone. And the levels you saw in H₂ — σ and σ* — are the seed of it: pool N orbitals and the two levels fan into a band.

Bridge-Burners LLC · Fiddler · Na⁺ lattice + electron sea · 2 levels → N → band · anchor: AKASHA

N atoms =2 (σ, σ*)

State

levels in band2

band fillinghalf

Fermi levelmid-band

conducts?yes

Bare numbers (Na metal)

lattice	BCC, 3s¹ → 1 e⁻/atom to the sea
cohesive E	≈ 107 kJ/mol (1.11 eV/atom) — soft metal
Fermi energy	E_F ≈ 3.2 eV
e⁻ density	n ≈ 2.6 × 10²² cm⁻³

Status discipline

LiteralMetallic bond = cation lattice + delocalized valence e⁻; N orbitals → N-level band; 1 e⁻/atom → half-filled → empty levels just above E_F → conducts. Non-directional → malleable. Na cohesive ≈107 kJ/mol.

BridgeThe "sea"; covalent shares with one, metallic shares with all; the 2→N limit of σ/σ* is the band — straight into the band sector.

SpeculativeThe free-electron sea is a model — real electrons are Bloch waves in a periodic potential, not a classical gas. The dots are schematic.