Fluorine, achemical element with the symbol F and atomic number 9, is the lightest halogenand exist as a highly toxic diatomic gas with a pale yellow appearance at normal pressureand temperature. Fluorine is the most reactive chemical element with thehighest electronegativity value of 3.98 according to the Pauli scale so that itcan react with all other elements except helium, neon, and argon.

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Elemental fluorineand mostly all the fluorine compounds are produced from hydrogen fluoride (HF).It is widely used as refrigerant gas (ferons), production of polymers(fluoropolymers, PTFE), surfactants, agrichemical, and in many other applications.

You are here toknow valence electrons of fluorine atom, aren’t you? Don’t worry along with fluorinevalence electrons we will explain its valency also. But before that let’s havesome basic ideas about what these two terms are:

Difference BetweenValence Electrons and Valency

Valence electronsare the total number of electrons present in the outermost shell of an atom(i.e. in outermost orbital). The valence electrons for a neutral atom arealways definite, it cannot be varied (more or less) in any condition for aparticular atom and may or may not be equal to its valency.


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Valency is definedas the total number of electrons, an atom can lose, gain, or share at the timeof bond formation to get a stable electronic configuration i.e. to complete anoctet. The valency of an atom can be variable in different compounds orchemical reactions due to the different bonding circumstances. Most of the timevalency varies/changes due to change in oxidation and reduction states.

Fluorine (F)Valence Electrons

There are foursimple steps to find out the valence electrons for fluorine atom which are:

Step 1: Find theAtomic Number


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To find out theatomic number of fluorine, we can use the periodic table. With the help of theperiodic table, we can easily see that the atomic number of fluorine is 9. Asits atomic number is 9, it has 9 protons, and for neutral fluorine, the numberof protons is always equal to the number of electrons i.e. has 9 electrons inits nucleus.

Step 2: WriteElectron Configuration


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Electronconfiguration is the arrangement of electrons on the orbitals. The fluorineatom has a total of 9 electrons so, we have to put 9 electrons in orbitals. Theelectrons will be placed in different orbitals according to the energy level:<1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f>. Now,

Fluorine electronconfiguration F (9) =1s22s22p5(completeconfiguration).

= 2s22p5(condensed configuration).

Step 3: DetermineValence Shell

As we know, thevalence shell of an atom can be found from the highest number of principlequantum numbers which are expressed in the term of n, and in 2s22p5, thehighest value of n is 2 so that the valence shell of fluorine is2s22p5.

Step 4: FindValence Electrons

The total number ofelectrons present in the valence shell of an atom is called valence electrons,and there are a total of seven electrons present in the valence shell of fluorine(2s22p5). Thus,fluorine has seven valence electrons.

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Valency of Fluorine(F)

There are manydifferent ways to find out the valency of an atom which reflects the ability ofan atom to bond with other atoms. Valence describes how easily an atom or afree radical can combine with other chemical species. The valency of an atom isdetermined based on the number of electrons lost, gained, or shared withanother atom at the time of bond formation.

An atom is said tobe stable when its outermost shells have eight electrons (except H & He).If the total number of electrons in outermost shells is between one to four,the atom has positive valency and if electrons are between four to eight, thevalency is calculated by subtracting from eight and valency will be zero. Atomshaving four outermost electrons possess both positive and negative valency, andatoms having eight outermost electrons, valency will be zero (i.e. noblegases).

Elements like fluorinecan reach the stable state (nearest inert gas configuration: Ne) by getting oneelectron.So that the valency of fluorine is 1.

Mathematically, theelectronic configuration of fluorine is 2, 7. And as we know, if electrons inoutermost shell exceeds from 4, it should be subtracted from 8. So,

ElectronConfiguration of fluorine (S) = 2, 7

We can see the outermost shell of fluorine has 6 electrons so, have to subtract it from 8.

8 – 7 = 1

That’s why valencyof fluorine is 1.

Note: In general, fluorinehas a stable oxidation state of -1 most of the time but it can differ insome compound like F2 and HOF where its oxidation state is 0 and +1respectively. Do not confuse with -1 or something else (0 or +1) with positiveor negative signs, it is just an oxidation number that can vary from compound tocompound. But its valency is always 1 in any case.

In another sense, afluorine atom can form a maximum of one covalent bond in a chemical bonding (Forexample: HF, SiF4, CF4, etc.), and that what valency is, the maximum ability toform bonds with atoms at the time of chemical bonding.

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We can also findthe valency of fluorine with the help of the periodic table. As fluorinebelongs to group 17 (17A or VIIA) along with chlorine (Cl), bromine (Br), and iodine(I), and astatine (At). These group elements are also called halogens. All theseelements have a valency of one.