Molecule Builder

Place atoms · drag them into position · click one then another to bond.

Elements (click canvas to place)

Placing: Hydrogen (valence 1)

Bond Type

Click atom → click another to bond

Legend

Valence complete
Needs more bonds
Selected

Hydrogen

H
Outer electrons1 of 2
Electronegativity2.2
0 metal24 F

Medium — forms fairly balanced covalent bonds.

Needs 1 more electron to fill its first shell (max 2). Only ever forms one bond.

Single bonds only

H₂ · H₂O · CH₄ · HCl

lone pair bond slot
Select an element, then click here to place atoms

Formula

How Molecules Bond

Atoms share electrons to fill their outer shells. Teal = shared (bonding) electrons · Amber = lone pairs (not shared).

Single Bond —

1 shared pair · 2 electrons

HH

One electron from each atom joins into a shared pair. The most common bond. H₂, HCl, and H₂O all use single bonds.

e.g. H₂ · HCl · CH₄ · NaCl

Double Bond =

2 shared pairs · 4 electrons

OO

Two pairs of electrons are shared. Stronger and shorter than a single bond. Oxygen uses double bonds in O₂ and CO₂.

e.g. O₂ · CO₂ · SO₂

Triple Bond ≡

3 shared pairs · 6 electrons

NN

Three shared pairs — the strongest and shortest covalent bond. N₂ is so stable it makes up 78% of the air we breathe.

e.g. N₂ · CO · C₂H₂

Element Valence Quick Reference

H
1 bond
1e⁻
C
4 bonds
4e⁻
O
2 bonds
6e⁻
N
3 bonds
5e⁻
Cl
Chl
1 bond
7e⁻
Na
Sod
1 bond
1e⁻
S
2 bonds
6e⁻
F
1 bond
7e⁻
Ca
Cal
2 bonds
2e⁻