Methane

CH₄ · methane

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Carbon forms four identical C–H single bonds with no lone pairs, the textbook tetrahedral molecule at exactly 109.5°.

Valence electrons: 8
Charge: 0
Lone pairs: 0
Molecular geometry: tetrahedral

Lines represent covalent bonds (shared electron pairs); dots represent lone pairs (nonbonding electrons).
A single bond is one shared pair of electrons, a double bond two shared pairs, and a triple bond three shared pairs.
Each atom in a bond contributes to the shared pair and counts the shared electrons toward its own octet. The atoms do not each gain two extra electrons; they share the same pair, and both atoms count it.

Count

Begin by counting , the outer-shell electrons that participate in bonding: carbon is a Group 14 element, so it has 14 - 10 = 4 valence electrons; each hydrogen is a Group 1 element, so it has 1 valence electron, and with 4 of them that is 1 × 4 = 4, which totals 8 valence electrons, the only electrons available to build the structure, so every bond and placed later must be drawn from this count.

Build

The must bond to every other , so it cannot be hydrogen: with one , hydrogen forms only one bond and is always terminal. That leaves carbon as the central atom.
Begin the structure with a from C to each of the 4 terminal . Each single bond is a shared pair, so these bonds together use 8 electrons and 0 of the 8 are still available.
Every here is hydrogen, and a hydrogen is complete with just two electrons (a ), which its already supplies. No are added to the terminals, so all 0 remaining electrons are available for C.
With the terminal octets complete, no electrons remain, so C receives no at this stage.

Verify

Before continuing, check the total electron count surrounding each . C: 8 shared + 0 nonbonding = 8 (a full ); each H: 2 shared + 0 nonbonding = 2 (a duet, all hydrogen needs).
Check the on each . Formal charge equals an atom's , minus its nonbonding (lone-pair) electrons, minus half of its ; the bonding electrons are halved because the two atoms in a bond share that pair equally, so each is assigned one electron of it. Here all 5 atoms have a formal charge of zero, which is the ideal outcome and confirms this is the preferred structure.

Watch out

The usual slip on CH4 is miscounting hydrogen: it's in group 1, so each H brings exactly one electron and holds exactly one bond. 4 hydrogens means 4 electrons from them, never more.

Shape

Determine the using : C is surrounded by 4 bonding domains and 0 , for 4 in total. Because electron domains repel one another, 4 domains arrange themselves as far apart as possible, giving tetrahedral and sp³ .
Every domain carries an here, so and agree: tetrahedral, 109.5° angles throughout.
: C and H pull almost equally on their , so there's no meaningful dipole anywhere. Nonpolar.

Worth knowing

Methane is the perfect tetrahedron: four identical bonds, 109.5 degrees everywhere. It is the main component of natural gas, and for molecule it traps far more heat in the atmosphere than CO2 does.