How Many Valence Electrons Does Fluorine (F) Have? [Valency of Fluorine]

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

Elemental fluorine and 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 to know valence electrons of fluorine atom, aren’t you? Don’t worry along with fluorine valence electrons we will explain its valency also. But before that let’s have some basic ideas about what these two terms are:

Difference Between Valence Electrons and Valency

Valence electrons are 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 are always definite, it cannot be varied (more or less) in any condition for a particular atom and may or may not be equal to its valency.

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

Fluorine (F) Valence Electrons

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

Step 1: Find the Atomic Number

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

Step 2: Write Electron Configuration

Electron configuration is the arrangement of electrons on the orbitals. The fluorine atom has a total of 9 electrons so, we have to put 9 electrons in orbitals. The electrons 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 electron configuration F (9) = 1s22s22p5(complete configuration).

= [He] 2s22p5 (condensed configuration).

Step 3: Determine Valence Shell

As we know, the valence shell of an atom can be found from the highest number of principle quantum numbers which are expressed in the term of n, and in [He] 2s22p5, the highest value of n is 2 so that the valence shell of fluorine is 2s22p5.

Step 4: Find Valence Electrons

The total number of electrons 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.

Also Read:

• Valence Electrons & Valency of Carbon (C).
• Valence Electrons & Valency of Hydrogen (H).
• Valence Electrons & Valency of Sulfur (S).

Valency of Fluorine (F)

There are many different ways to find out the valency of an atom which reflects the ability of an atom to bond with other atoms. Valence describes how easily an atom or a free radical can combine with other chemical species. The valency of an atom is determined based on the number of electrons lost, gained, or shared with another atom at the time of bond formation.

An atom is said to be 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, the valency is calculated by subtracting from eight and valency will be zero. Atoms having four outermost electrons possess both positive and negative valency, and atoms having eight outermost electrons, valency will be zero (i.e. noble gases).

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

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

Electron Configuration of fluorine (S) = 2, 7

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

8 – 7 = 1

That’s why valency of fluorine is 1.

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

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

We can also find the valency of fluorine with the help of the periodic table. As fluorine belongs 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 these elements have a valency of one.