What is Electron Configuration of Fluorine (F)?

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Orbit Electron Configuration of Fluorine (F) atom is two electrons in first orbit (K) and 7 electrons in second orbit (L)

Orbital Electron Configuration of Fluorine (F) atom is 1s2 2s2 2p5 which means Fluorine atom have two electrons inside 1s orbital, two electron in 2s orbital and 5 electrons in 2p orbitals

Also we can replace 1s2 with [He], therefore electron configuration of Fluorine (F) is [He] 2s2 2p5

F is the symbol for the element Fluorine, which is located at top of group 19 of the periodic table. Fluorine have total of nine electrons in its atomic structure. Fluorine is 13th most abundant element in the crust of Earth.

It is highly reactive element and can react with most of other elements. That’s why in the nature Fluorine doesn’t exist on it’s own rather mostly it’s found in compound form.

Existence of Fluorine was discovered by Swedish pharmacist/chemist Carl-Wilhelm Scheele in 1771 but for first time it was isolated by French pharmacist/chemist Henri Moissan in 1886. Henri was awarded Nobel Prize in Chemistry for isolating Fluorine in 1906.

Fluorine is 13th most abundant element in the Earth’s crust. Most common uses of Fluorine are air conditioning/refrigeration, in toothpaste for preventing dental cavities, flat panel display production.

Fluoride ion, which is formed when fluorine atom accepts an electron, is an essential ion for animals because it helps in strengthening teeth and bones. An average human body contains 3 milligrams of fluoride. But too much of it in human body can cause a disease called Fluorosis.

Fluorine is a pale yellow, diatomic, highly corrosive, flammable gas, with a pungent odour. It undergoes a strong reaction with water, which results in the production of oxygen and an extremely corrosive hydrofluoric acid (HF).

Electron configuration refers to the arrangement of electrons in different orbits and orbitals of an atom in a certain order. Depending upon whether electrons are being arranged in Orbits or Orbitals there are two types of electron configurations – Orbit Electron Configuration and Orbital Electron Configuration.

In this article, I’ve discussed both Orbit and Orbital Electron Configurations of Fluorine (F) atom.

Orbit Electron Configuration of Fluorine (F)

Niels Bohr, a Danish scientist, was the first to propose the concept of an orbit around an atom. In 1913, he presented a model of the atom to the scientific community. As per this model, the electrons in an atom follow a set path as they go around the nucleus in circular motion.

These set paths are called “Orbits” and are numbered as 1, 2, 3, ……… depending upon their closeness to nucleus of atom. So first circular path around nucleus is numbered as 1, second as 2 and so no. Moreover orbits are also denoted by English letters.

  • First orbit – K and have n = 1
  • Second orbit – L and have n = 2
  • Third orbit – M and have n = 3
  • Fourth orbit – N and have n = 4
  • and so on.

How many electrons any of these orbits can hold is determined by using formula 2n2 where n is number of orbit. Based upon this formula, different orbits in the atom can hold electrons as following.

  • First orbit – K (n = 1) can hold 2n2 = 2 (1)2 = 2 electrons
  • Second orbit – L and have n = 2 can hold 2n2 = 2 (2)2 = 2 (4) = 8 electrons
  • Third orbit – M and have n = 3 can hold 2n2 = 2 (3)2 = 2 (9) = 18 electrons
  • Fourth orbit – N and have n = 4 can hold 2n2 = 2 (4)2 = 2 (16) = 32 electrons
  • and so on.

As Fluorine atom have nine electrons, therefore it’s Orbit Electron Configuration will be two electrons in K orbit and seven electrons in L orbit.

Electron Configuration of Fluorine showing 2 electrons in K shell and 7 electrons in L shell

How many electron shells does Fluorine have?

Fluorine have electron configuration 2, 7 which means it have 2 electrons in K shell and 7 electrons in L shell. Therefore Fluorine have 2 electron shells.

How many electrons does Fluorine have in K shell?

2 electrons

How many electrons does Fluorine have in L shell?

7 electrons

Orbital Electron Configuration of Fluorine (F)

Niels Bohr proposed the idea that electrons revolve around nucleus in specific circular paths called Orbits, but later on Heisenberg found out that it’s impossible to determine position and velocity of an electron inside the atom at same time, so how it’s possible that electrons do circular motion on specific paths in an atom.

In later years, Erwin Schrodinger developed a mathematical formula to compute the probability of finding the location of an electron inside an atom.

On the basis of this probability, the location of an electron inside an atom could be represented as the chances of that electron being located in a certain three-dimensional area surrounding the nucleus.

As 3D region can be explained only using 3 parameters, therefore in order to describe where an electron is? inside the atom.

We need three numbers – Principle Quantum Number (n), Angular Momentum Number (l) and Magnetic Momentum Number (m).

Therefore Orbits(this concept was proposed by Neils Bohr) are further divided into sub-energy levels called subshells. How many subshells an orbit have is equal to Principle Quantum Number (n) of orbit.

Therefore

  • First Orbit (K and n = 1) have 1 subshell
  • Second Orbit (L and n = 2) have 2 subshell
  • Third Orbit (M and n = 3) have 3 subshell
  • Fourth Orbit (N and n = 4) have 4 subshell

These sub-energy levels/subshells have specific regions where probability of finding electrons is maximum. These subshells are names as s, p, d, f and have angular momentum numbers as 0, 1, 2 and 3 respectively.

Which type of subshell an orbit have can be determined using Angular Momentum Number (I).
So
If Principle Quantum Number of an orbit is n
Then subshells in that orbit are 0 to (n – 1)

If
Angular Momentum Number(l) = 0 that means it’s s orbital
Angular Momentum Number(l) = 1 that means it’s p orbital
Angular Momentum Number(l) = 2 that means it’s d orbital
Angular Momentum Number(l) = 3 that means it’s f orbital

First Orbit (K and n = 1)
Angular Momentum Number (l) = 0 to (1 – 1) = 0 (0 to 0)
Which means first orbit just have one subshell which is s

Second Orbit (L and n = 2)
Angular Momentum Number (l) = 0 to (2 – 1) = 1 (0 to 1)
Which means second orbit have two subshells which are s and p

Third Orbit (M and n = 3)
Angular Momentum Number (l) = 0 to (3 – 1) = 2 (0 to 2)
Which means third orbit have three subshells (0, 1, 2) which are s, p and d

Fourth Orbit (N and n = 4)
Angular Momentum Number (l) = 0 to (4 – 1) = 3 (0 to 3)
Which means fourth orbit have four subshells (0, 1, 2, 3) which are s, p, d and f

OrbitPrinciple Quantum NumberNumber of SubshellsSubshells
First Orbit (K)n = 111s
Second Orbit (L)n = 222s
2p
Third Orbit (M)n = 333s
3p
3d
Fourth Orbit (N)n = 444s
4p
4d
4f

These s, p, d and f subshells further have subregions which are called Orbitals, orbitals are just regions inside a subshell where probability of existence of an electron is quite high.

How many orbitals a subshell have depends upon it’s Angular Momentum Number (l) and can be calculated using formula.
Number of orbitals in a subshell = 2l + 1 where I is Angular Momentum Number of a subshell.

Therefore
s subshell (Angular Momentum Number l = 0)
Number of orbitals = 2(0) + 1 = 1
So s subshell just have one orbital

p subshell (Angular Momentum Number l = 1)
Number of orbitals = 2(1) + 1 = 3
So p subshell have three orbitals

d subshell (Angular Momentum Number l = 2)
Number of orbitals = 2(2) + 1 = 4 + 1 = 5
so d subshell have five orbitals

f subshell (Angular Momentum Number l = 3)
Number of orbitals = 2(3) + 1 = 6 + 1 = 7
so f subshell have seven orbitals

Moreover electron holding capacity of a subshell can be calculated using formula
Number of electrons which a subshell can hold = 2(2I + 1) where I is Angular Momentum Number of subshell

Therefore
s subshell (Angular Momentum Number l = 0)
Number of electrons it can hold = 2(2(0) + 1) = 2(1) = 2
So s subshell can hold maximum two electrons

p subshell (Angular Momentum Number l = 1)
Number of electrons it can hold = 2(2(1) + 1) = 2(3) = 6
So p subshell can hold maximum six electrons

d subshell (Angular Momentum Number l = 2)
Number of electrons it can hold = 2(2(2) + 1) = 2(4 + 1) = 2(5) = 10
so d subshell can hold maximum ten electrons

f subshell (Angular Momentum Number l = 3)
Number of electrons it can hold = 2(2(3) + 1) = 2(6 + 1) = 2(7) = 14
so f subshell can hold maximum fourteen electrons

SubshellAngular Momentum Number (I)Number of Orbitals in
Subshell (2l + 1)
Maximum Electrons Subshell can hold 2(2l + 1)
s012
p136
d2510
f3714

Summarising all this we can write energy levels in an atom as

1s
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f 5g

But next question which arises is “in which order these orbitals should be filled in to figure out electron configuration of an atom?”.

Like should 2 electrons be filled in 1s orbital first or 3p orbital first???

Well answer to this question is Aufbau Principle.

According to the Aufbau Principle, in the ground state of an ion or an atom, electrons first occupy the atomic orbitals of lowest energy levels before filling up in higher energy levels. What this indicates is that the orbital with the lower energy will be filled first, followed by the orbital with the greater energy.

As per this principle energy of any orbital depends upon sum of Principle Quantum Number (n) and Angular Quantum Number (l).
Therefore
Energy of Orbital = n + l

So lower the value of n + l is lower its energy.

OrbitalnIEnergy (n + l)
1s101
2s202
2p213
3s303
3p314
3d326
4s404
4p415
4d426
4f437

From the above table its clear that 4s have less energy than 3d, so it should be filled first.
Based upon the energies of orbitals as per Aufbau Principle, order of filling of orbitals is 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p 8s and so on.

It’s tricky to remember what’s order of filling of orbitals as per Aufbau Principle, so you can use below diagram for easily filling up orbitals. Just follow the arrows from top right corner to bottom left corner diagonally.

Order of filling orbitals in an atom as per Aufbau Principle
Aufbau Principle Filling Of Orbitals Order

Order of filling of orbitals as per Aufbau Principle is 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p 8s and so on.

As Fluorine atom have nine electrons, therefore it’s electron configuration is 1s2 2s2 2p5. Which means Fluorine atom have 2 electrons each in its 1s, 2s orbitals and 5 electrons in 2p orbitals.

Electron Configuration of Fluorine 1s2 2s2 2p5
FluorineElectron Configuration
1s2 2s2 2p5

How do you write the electron configuration for Fluorine?

Fluorine atom in total have nine electrons, to write down the electron configuration of fluorine, the first two electrons would go into the 1s orbital. Because the 1s orbital can only accommodate two electrons, next two electrons are placed in the 2s orbital. The remaining five electrons would go in the 2p subshell orbitals. Putting all this together, electron configuration of fluorine is 1s2 2s2 2p5. Which can also be written as [He] 2s2 2p5 where [He] represents electron configuration of noble gas Helium.

How many orbitals are in Fluorine Atom?

Electron Configuration of fluorine atom is 1s2 2s2 2p5 which means
Fluorine Atom have
– 2 electrons in 1s subshell
– 2 electrons in 2s subshell
– 5 electrons in 2p subshell

1s subshell have just one orbital
2s subshell also just have one orbital
2p subshell have 3 orbitals

So in total fluorine atom 1 + 1 + 3 = 5 orbitals

Therefore Fluorine atom have 5 orbitals.

Valence Electrons of Fluorine (F)

Number of electrons in the last orbit of an element’s atom are called valence electrons.

As Fluorine have electron configuration 1s2 2s2 2p5 so it’s last orbit is 2 (L shell which have Principle Quantum Number n = 2), as last orbit of Fluorine have 7 electrons (2 in 2s and 5 in 2p subshell), therefore number of valence electrons in Fluorine is seven.

Fluorine (F)7 valence electron

How many Valence Electrons does Fluorine have?

Fluorine have 7 valence electrons as it’s Orbital Electron Configuration is 1s2 2s2 2p5. As electron configuration shows, fluorine have 7 valence electrons located in 2s and 2p subshells.

How many electrons does Fluorine require to reach an octet in it’s valence shell?

Electron configuration of fluorine in terms of shells is 2, 7 which means it have 2 electrons in K shell and 7 electrons in L shell. Though maximum capacity of L shell is to accomodate 8 electrons. Therefore if fluorine accepts 1 electrons then it’s configuration become 2, 8 and it’s L shell become full (as there are 8 electrons in L shell that’s why its called Octet).

Therefore in order to reach an octet in it’s valence shell fluorine need to gain 1 electrons.

Valency of Fluorine (F)

Valency refers to the ability of an element to combine with other elements. Valencies are same throughout the periodic table for elements that are located in the same group. 

Which means valency is same for all of Group 1 elements (K, Na etc. have valency = 1), Group 2 elements (Ca, Mg etc. have valency = 2) and so on for other groups in the periodic table. Also valency depends upon number of electrons that are found in an element’s outer most shell.

As Fluorine (F) have electron configuration 1s2 2s2 2p5, which means there are in total seven electrons in outermost subshell (2s and 2p subshells).

Fluorine usually combines with other elements by gaining or sharing electrons. In both cases, fluorine either share 1 of its 2p electrons with other atoms to form covalent single bond or gains 1 electrons to become fluoride (F) ion.

In both of these cases, Fluorine achieves more stable electronic configuration of Neon noble gas (1s2 2s2 2p6)

Therefore valency of Fluorine (F) is 1.

Fluorine (F)Valency = 1

Does Fluorine have Valency 1?

Valency refers to the ability of an element to combine with other elements and depends upon number of electrons available in outermost shell of atom.

Fluorine atom has two shells K and L.
Its electron configuration is 1s2 2s2 2p5 and therefore it can either share or gain 1 electron to achieve more stable electron configuration of nearest noble gas Neon (1s2 2s2 2p6). As fluorine just need 1 electron therefore valency of fluorine is 1.

Fluorine Anion or Fluoride (F) Electron Configuration

Above I discussed that in order to achieve stable electron configuration, in which all of orbitals are fully filled with electrons. Fluorine want to gain 1 electrons in 2p orbitals and achieve electron configuration of Neon noble gas.

But when an atom of Fluorine does again 1 electron, then number of protons(positive charge) and number of electrons(negative charge) becomes unequal.

Thus forming a Fluoride (F) ion. Which have 2 electrons more than number of protons.

F + e → F

So Orbital Electron Configuration of Fluorine (F) atom is 1s2 2s2 2p5 and after gaining just one electron it becomes 1s2 2s2 2p5.
Therefore Electron Configuration of Fluoride (F) ion is 1s2 2s2 2p6.

Electron Configuration of Fluoride (F-) is 1s2 2s2 2p6

How many electrons are in fluorine ion F-?

Fluorine ion (F) also called Fluoride Ion is formed when a Fluorine atom gain an electron, as fluorine atom just have 9 electrons and gains a electron to become fluorine ion. Therefore, fluorine ion (F) have 10 electrons.

Summary

Electron Configuration of Fluorine is 1s2 2s2 2p5
Electron Configuration of Fluoride Ion (F) is 1s2 2s2 2p6

FAQs

What is Valency of Fluorine?

Flourine usually combines with other elements by gaining or sharing electrons. In both cases, fluorine either share 1 of its 2p electrons with other atoms to form covalent single bond or gains 1 electron to become fluoride (F) ion. Therefore valency of Fluorine (F) is 1.

What is electron configuration of neutral fluorine?

Neutral Fluorine atom means that it have equal number of electrons and protons. As in neutral state Fluorine atom have nine electrons, therefore it’s electron configuration is 1s2 2s2 2p5. Which means Fluorine atom have 2 electrons each in its 1s, 2s orbitals and 5 electrons in 2p orbitals.

What is electron configuration of ground-state fluorine atom?

Ground state atom means that all electrons inside it are in least possible energy state levels, therefore net total energy of atom in ground-state is minimum out of all possible states of it. As Fluorine atom just have 9 electrons, therefore it’s electron configuration is 1s2 2s2 2p5. Which means Fluorine atom have 2 electrons each in its 1s, 2s orbitals and 5 electrons in 2p orbitals.

What is electron configuration of fluoride ion (F-)?

When an atom of fluorine gains 1 electron, then number of protons(positive charge) and number of electrons(negative charge) becomes unequal. Thus forming a fluoride ion (F). As electron configuration of fluorine atom is 1s2 2s2 2p5 and formation of fluoride ion (F) require gaining of 1 electron therefore electron configuration of fluoride ion is 1s2 2s2 2p6.

Some Properties of Fluorine

Element NameFluorine
SymbolF
Atomic Number9
Number of electrons9
Group in Periodic Table17
Atomic Weight18.998 u
Number of Valence Electrons7
Valency1
Oxidation States– 1
Melting Point-219.6 °C (53.53 K)
Boiling Point-188.1 °C (85.04 K)
Atomic Radius147 picometre
Electronegativity3.98 on Pauling Scale
(Fluorine is most electronegative element)
Van der waals Radius147 picometre
Covalent Radius60 picometre
Electron Affinity328 kJ/mol
Density1.696 g/litre
F – F Bond Enthalpy155 kJ/mol
C – F Bond Enthalpy485 kJ/mol
H – F Bond Enthalpy565 kJ/mol
First Ionisation Energy1680.6 kJ/mol
Second Ionisation Energy3134 kJ/mol
Third Ionisation Energy6050 kJ/mol

Some Uses of Fluorine

Chlorofluorocarbons are used extensively used in air conditioners and refrigerators
Fluorides are also added to toothpaste to prevent dental cavities
The metal could be used to map the circulatory system and any disorders

Physical Properties of Fluorine

Fluorine exists naturally in the earth’s crust and found in coal, clay, and rocks
Hydrogen fluorides are released into the air by the industries through the processes of combustion
0.6 ppb of fluorine is present as organic chloride compounds and salt spray in the atmosphere
The element has been recorded around 50 ppb in city environments

Compounds of Fluorine

Fluorine Compound NameFluorine Compound Formula
Calcium FluorideCaF2
Xenon DifluorideXeF2
Hydrogen FluorideHF
Sodium FluorideNaF
DichlorodifluoromethaneCF2Cl2

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