Valence Electrons Calculator & Chart
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How to find valence electrons
- Main-group elements (groups 1, 2, 13–18): read the group number. Groups 1 and 2 have 1 and 2; for groups 13–18 subtract 10.
- From the electron configuration: add the electrons in the highest shell number. Sulfur, [Ne] 3s² 3p⁴, has 2 + 4 = 6.
- Transition metals: count the outer s electrons plus the d electrons just below them (iron, [Ar] 3d⁶ 4s², is counted as 8), though only the 4s pair sits in the outermost shell.
Valence electrons by group
| Group | Valence electrons | Examples | Typical ion |
|---|---|---|---|
| 1 | 1 | H, Li, Na, K | 1+ |
| 2 | 2 | Be, Mg, Ca | 2+ |
| 13 | 3 | B, Al, Ga | 3+ |
| 14 | 4 | C, Si, Ge | — |
| 15 | 5 | N, P, As | 3− |
| 16 | 6 | O, S, Se | 2− |
| 17 | 7 | F, Cl, Br | 1− |
| 18 | 8 | Ne, Ar, Kr (He: 2) | none |
Valence electrons chart (periodic table)
Tap an element for its valence electrons, Lewis dot symbol and electron configuration.
Main-group values are electrons in the outermost shell. Transition-metal values are outer s + inner d electrons, the usual textbook convention.
Ask about valence electrons
AI answers can be wrong. The calculators on this page are deterministic; trust them for numbers.
Why valence electrons matter
Chemistry happens at the edge of the atom. Sodium has one valence electron and gives it up to become Na⁺; chlorine has seven and takes one to become Cl⁻. Carbon’s four let it form four covalent bonds, the backbone of organic chemistry. Count them for any element using its electron configuration: add up the electrons in the highest-numbered shell.
Questions students ask
How do I find valence electrons?
Find the element’s group (column). Groups 1 and 2 have 1 and 2 valence electrons; groups 13 to 18 have the group number minus 10 (so 3 to 8). Helium is the exception with 2. Or write the electron configuration and add up the electrons in the highest-numbered shell: chlorine, [Ne] 3s² 3p⁵, has 2 + 5 = 7.
How many valence electrons are in each group?
Group 1: 1 · group 2: 2 · group 13: 3 · group 14: 4 · group 15: 5 · group 16: 6 · group 17: 7 · group 18: 8 (helium 2). Transition metals (groups 3–12) are usually counted as their outer s electrons plus the d electrons below them, which equals the group number for most of them.
What is a valence electron in simple terms?
An electron in the outermost shell of an atom. These are the electrons that take part in bonding, so they decide how an element reacts, what charge its ions carry and how many bonds it forms.
What is a diagram of valence electrons?
A Lewis dot symbol: the element’s symbol with one dot per valence electron, placed singly on the four sides before any side gets a second dot. Oxygen gets six dots, two sides paired and two single.
How many valence electrons does oxygen have?
Six. Oxygen is in group 16 with configuration 1s² 2s² 2p⁴; the second shell holds 2 + 4 = 6.
How many valence electrons does nitrogen have?
Five (2s² 2p³), which is why nitrogen usually forms three bonds and keeps one lone pair.
How many valence electrons does carbon have?
Four (2s² 2p²), which is why carbon forms four bonds.
What is the octet rule?
Main-group atoms tend to gain, lose or share electrons until they have eight in their outer shell, the arrangement of a noble gas. Hydrogen and helium aim for two. There are exceptions, such as boron in BF₃ (six) and sulfur in SF₆ (twelve).