Fluorine (F)
Fluorine is element 9, a halogen in group 17, period 2. A neutral atom has 9 protons, 10 neutrons and 9 electrons, 7 of them valence electrons.
Halogen- Atomic number
- 9
- Atomic mass
- 18.998 u
- Valence electrons
- 7
- Protons · neutrons
- 9 · 10
- Electrons per shell
- 2, 7
- At room temperature
- gas
Bohr model of fluorine
The Bohr model draws fluorine as a nucleus of 9 protons and 10 neutrons, with its 9 electrons on 2 circular shells: 2 in shell 1, 7 in shell 2. Press Build the atom to watch the shells fill from the inside out. The outer ring (the L shell) is dashed: the electrons there are the ones that take part in chemistry.
Real electrons don't travel in neat circles. They live in fuzzy orbitals, shown below, but the Bohr picture is the quickest way to count shells and valence electrons.
Electron configuration of fluorine
1s² 2s² 2p⁵
Short form (noble gas notation): [He] 2s² 2p⁵. The [He] stands for the electrons of helium, the noble gas before it.
How many valence electrons does fluorine have?
Fluorine has 7 valence electrons.
Fluorine is in group 17, and for groups 13–18 you subtract 10 from the group number: 17 − 10 = 7. It tends to gain 1 electron to complete an octet, forming a −1 ion.
Protons, neutrons and electrons
| Protons | 9 | equal to the atomic number |
|---|---|---|
| Electrons | 9 | equal to the protons in a neutral atom |
| Neutrons | 10 | mass number 19 − 9 protons |
Atoms of the same element can have different numbers of neutrons (isotopes). The count above uses the rounded atomic mass, the way it's taught in class.
Fluorine properties
| Symbol | F |
|---|---|
| Category | Halogen |
| Group · period · block | 17 · 2 · p |
| Atomic mass | 18.998 u |
| State at 25 °C | gas |
| Melting point | 53.53 K (-220 °C, -363 °F) |
| Boiling point | 85.03 K (-188 °C, -307 °F) |
| Density | 0.0017 g/cm³ |
| Electronegativity (Pauling) | 3.98 |
| Atomic radius | 135 pm |
| First ionization energy | 17.423 eV |
| Electron affinity | 3.339 eV |
| Oxidation states | −1 |
| Common ion charge | −1 |
| Discovered | 1670 by André-Marie Ampère |
Where fluorine sits on the periodic table
Group 17: Chlorine, Bromine, Iodine, Astatine, Tennessine.
Questions about fluorine
How many valence electrons does fluorine have?
Fluorine has 7 valence electrons.
How many protons, neutrons and electrons does fluorine have?
A neutral fluorine atom has 9 protons and 9 electrons. Its most common form has about 10 neutrons (mass number 19 − 9 protons).
What is the electron configuration of fluorine?
1s² 2s² 2p⁵, written in short form as [He] 2s² 2p⁵.
What does the Bohr model of fluorine look like?
A nucleus of 9 protons and 10 neutrons, circled by 2 electron shells holding 2, 7 electrons.
What is the atomic number of fluorine?
9. The atomic number is the number of protons in the nucleus, and it is what makes an atom fluorine.