Fluorine (F)
Element 9 · halogen · group 17, period 2
Fluorine is element 9, a halogen in group 17 and period 2. Its electron configuration is [He] 2s2 2p5. That leaves 7 valence electrons in the outer shell, with the shells filling 2, 7. It is 1 electron short of a full octet, so it gains them and carries a charge of -1.
- 9 protons
- 7 valence e−
- -1
- p-block
Fluorine Lewis dot structure
Fluorine has 7 valence electrons, so its Lewis symbol carries 7 dots: three pairs and one single dot. The dots go one to a side before any of them pair up, so the unpaired ones show exactly how many bonds the atom tends to form. The ion has gained 1 more to fill its shell, so all 8 are drawn as pairs.
Draw it in the Lewis structure generator →
Properties
| Atomic number | 9 |
|---|---|
| Symbol | F |
| Standard atomic weight | 18.998 u |
| Group | 17 |
| Period | 2 |
| Block | p-block |
| Category | halogen |
| Electron configuration | 1s2 2s2 2p5 |
| Noble-gas notation | [He] 2s2 2p5 |
| Electrons per shell | 2, 7 |
| Valence electrons | 7 |
| Common ionic charge | -1 |
| Electronegativity (Pauling) | 3.98 |
| Protons / electrons | 9 / 9 |
Electron configuration of fluorine
Orbitals fill from the lowest energy upward. Writing that out for fluorine gives 1s2 2s2 2p5, which is 1s2 2s2 2p5 in plain text.
Everything up to He is the same as in that noble gas, so it is usually abbreviated to [He] 2s2 2p5. The part outside the bracket is what does the chemistry.
| Subshell | Electrons | Capacity |
|---|---|---|
| 1s | 2 | 2 |
| 2s | 2 | 2 |
| 2p | 5 | 6 |
Fluorine ion charge
Fluorine commonly forms ions with a charge of -1.
It has 7 valence electrons, so it is 1 short of a full octet and 7 above an empty outer shell. An atom takes whichever route is shorter, which is why the charge comes out as it does.
Common questions
What is the Lewis dot structure of fluorine?
The symbol F with 7 dots, one for each valence electron: three pairs and one single dot. Dots go one to a side before any pair up, the same way electrons fill separate orbitals before sharing one. The F- ion is drawn in brackets with all eight, because it has gained 1.
How many valence electrons does fluorine have?
Fluorine has 7 valence electrons. For a main-group element the count is the group number minus 10, and fluorine is in group 17.
What is the electron configuration of fluorine?
1s2 2s2 2p5, or [He] 2s2 2p5 written from the previous noble gas. Orbitals fill lowest energy first.
What is the charge of fluorine?
Fluorine commonly forms ions with a charge of -1. With 7 valence electrons it is 1 short of an octet and 7 above an empty shell, so it takes whichever route is shorter.
How many protons, electrons and neutrons does fluorine have?
A neutral fluorine atom has 9 protons and 9 electrons. Its standard atomic weight is 18.998, so the most common isotope has about 10 neutrons.
Fluorine in Lewis structures
What the configuration above means in practice. Fluorine brings 7 valence electrons to each of these, and the working on every one of them starts by counting exactly that.
Nearby elements
See the ionic charge of every element →