How to draw KF Lewis Structure? - Science Education and Tutorials

The potassium fluoride chemical formula is KF. Drawing KF Lewis Structure is very easy to by using the following method. Here in this post, we described step by step method to construct KF Lewis Structure. The fluorine and potassium elements come as members of the halogen and alkaline metal family groups from the periodic table respectively. The valence electrons in fluorine and potassium are seven and one respectively. Potassium fluoride is used to make chemical reagents for organic chemical reactions as a brominating agent in organic chemistry.

Table of Contents

Key Points To Consider When Drawing The KF Electron Dot Structure

A three-step approach for drawing the KF Lewis structure can be used. The first step is to sketch the Lewis structure of the KF molecule, to add valence electrons around the fluorine atom; the second step is to add valence electrons to the one potassium atom, and the final step is to combine the step1 and step2 to get the KF Lewis Structure.

The KF Lewis structure is a diagram that illustrates the number of valence electrons and bond electron pairs in the KF molecule. The geometry of the KF molecule can then be predicted using the Valence Shell Electron Pair Repulsion Theory (VSEPR Theory), which states that molecules will choose the KF geometrical shape in which the electrons have from one another.

Finally, you must add their bond polarities to compute the strength of the one K+—F- single bonds (dipole moment properties of the KF molecule). The potassium-fluorine ionic bonds in potassium fluoride(KF), for example, are polarised toward the more electronegative fluorine in KF molecule, and because both bonds have the same size and are located around one potassium terminal of the linear structure with three lone pairs (in total eight electrons) on the fluorine atom as fluoride ion(F-), their sum of dipole moment is nonzero due to the KF molecule’s bond dipole moment and less electron polarity to the potassium atoms and become potassium ion. Because K+—-F- bonds polarity is not canceled in the KF molecule due to the presence of four lone pairs of electrons in the linear structure. The potassium fluoride(KF) molecule is classified as a polar ionic molecular crystal.

The molecule of potassium fluoride(linear-shaped molecular geometry) is tilted, the bond angles between fluorine (as fluoride ion) and potassium (as potassium ion) are 180 degrees. It has a difference in electronegativity values between fluorine and potassium atoms, with central fluorine’s pull being higher than terminal potassium’s in the KF ionic molecule. But they do not cancel each other due to the linear structure with four lone pairs in the molecular geometry of the KF molecule.

As a result, it has the nonzero dipole moment. The KF molecule has a nonzero dipole moment due to an unequal charge distribution of negative and positive charges. But both fluorine and potassium atoms fall on the halogen and alkaline metal family groups in the periodic table respectively. The fluorine atom is a more electronegative value than potassium in the KF ionic molecule. The KF molecule has the net dipole moment of non-zero value in the ground state energy level.

KF molecule has one K+—–F- single bond. Its dipole moment in the ground state is totally different as compared with the excited state. If it absorbs light may be from visible or UV light. It undergoes pi to pi star and n to pi star transition from ground state energy level to excited state energy level. In the excited state energy level, the KF ionic molecule shows a definite dipole moment. But it is very dynamic in nature.

Molecules can be classified as polar or nonpolar. The molecule polar behaves in a different manner as compared to nonpolar.

Overview: KF Lewis Structure

The central atom is fluorine, which is bordered on two terminals with potassium atoms(linear structural geometry), and four lone pairs on the central fluorine atom in the linear molecular geometry. Fluorine has seven outermost valence electrons, indicating that it possesses seven electrons in its outermost shell, whereas potassium also has one valence electron in its outermost shell. To complete the octet of the fluorine atom requires one valence electron on each of their outermost shell.

One potassium atom establishes covalent connections with the central fluorine atom as a result, leaving the fluorine atom with three lone pairs. There are three lone pairs of electrons on the fluorine central atom that resists the bond pairs of the K+—-F- bond. According to VSEPR theory, the K+—-F- ionic bond pairs polarity lead the KF molecule to take on the linear geometry structure.

The KF molecule’s one K+—-F- bonds are arranged in asymmetrical polarity order around the linear molecular geometry, giving rise to the KF molecular shape. The KF molecule has a linear molecular geometry because there is an electrical repulsion between the lone pairs of electrons in fluorine and one single ionic bond pair(K-F) of the KF molecule.

Lewis structure of KF has dot electron representative structure. Valence electrons of atoms undergo orbitals mixing in the chemical reactions, giving new types of molecular species of KF. The molecule is nothing but a bundle of valence electrons from the atoms. But it is converted to ionic bond pairs and lone pairs in the molecular structure.

Electronegative value Difference Calculation of KF Molecule:

Fluorine and potassium Electronegative difference in KF:

The fluorine atom has an electronegativity of 3.98, while potassium has an electronegativity of 0.93 in the KF ionic molecule. The difference in electronegativity of fluorine and potassium can be estimated using the method below.

The electronegative value difference between fluorine and potassium in KF molecule

Electronegativity value of fluorine= 3.98

Electronegativity value of potassium= 0.82

Difference of electronegativity value between fluorine and potassium in KF molecule = 3.98 – 0.82 = 3.16. Electronegativity difference between K-F ionic bond calculation of KF molecule

The electronegative difference between fluorine and potassium is greater than 0.5. This indicated the bond polarity moves near to polar nature. K-F ionic bond polarity in the KF molecule is polar.

Because of this difference in electronegativity of fluorine and potassium atoms, the KF molecule’s K+—F- bond becomes nonpolar. The total net dipole moment of the KF molecule is nonzero due to the cancellation of the bond dipole moment in the linear geometry due to the presence of three lone pairs of electrons. The electronegativity of an atom is the strength with which it may attract bound electron pairs to its side.

As a result, the K-F bond’s dipole moment is higher due to the polarization of the bonds and four lone pairs of electrons on fluorine, and all K-F bonds’ dipoles are arranged in the asymmetrical KF molecular geometry. The KF molecule has a nonzero net dipole moment.

The electron dot structure of the KF molecule is also known as the KF Lewis structure. It determines the number of outermost valence electrons as well as the electrons engaged in the KF ionic molecule’s bond formation. The outermost valence electrons of the KF molecule must be understood while constructing the Lewis structure of the molecule.

The fluorine atom is the middle element in KF molecular geometry, with seven electrons in its outermost valence electron shell, whereas the potassium atom has one electron in its outermost valence electron shell. The potassium atom has one valence electron.

The KF has a total of 8 valence electrons as a result of the foregoing above-said reasoning. With the core central fluorine atom, the one terminals with one potassium atom form ionic bonds, leaving the fluorine atom with four lone pairs in the middle of linear geometry.

Because three lone pairs on the terminal fluorine atoms create interaction with K-F bond pairs(but it is negligible in the ground state of the KF molecule). The bond angle of the K-F bond in the linear molecular geometry is approximately 180 degrees. This angle is greater than the CH4 molecule bond angle. The K-F bond length is 250 pm(picometer).

To sketch the KF Lewis structure by following these instructions:

Step-1: KF Lewis dot Structure by counting valence electrons on the fluorine atom

To calculate the valence electron of each atom in KF, look for its periodic group from the periodic table. The halogen and alkaline metal group families, which are the 17th and 1st groups in the periodic table, are both made up of fluorine and potassium atoms respectively. In their outermost shells, potassium and fluorine have one and seven valence electrons respectively.

Calculate the total number of valence electrons in the KF molecule’s outermost valence shell. The first step is to determine how many electrons are in the KF Lewis structure’s outermost valence shell. An electron in an atom’s outermost shell is known as a valence electron. It is represented by dots in the KF Lewis diagram. The KF molecule’s core fluorine atom can be represented as follows:

Total outermost valence shell electron of fluorine atom in KF= 7

Total outermost valence shell electron of potassium atom in KF= 1

The KF molecule has one central fluorine and one potassium atoms. Then the total outermost valence shell electrons can be calculated as follows

∴ Total outermost valence shell electrons available for KF Lewis structure( dot structure) = 7+1*1= 8 valence electrons in KF. calculation of total valence electron of KF molecule

Choose the atom with the least electronegative value atom and insert it in the center of the molecular geometry of KF. We’ll choose the least electronegative value atom in the KF molecule to place in the center of the KF Lewis structure diagram in this phase.

But in this case, potassium is the least electronegative than fluorine. Potassium loses one electron and forms potassium positive ions(K+). So that fluorine stays in the central molecular structure. The electronegativity value in periodic groups grows from left to right in the periodic table and drops from top to bottom.

The first step is to put seven valence electrons around the potassium atom as given in the figure.

Step-2: Lewis Structure of KF for counting valence electrons around the terminal potassium atoms

As a result, fluorine is the first atom in the periodic table’s halogen family group. Potassium is the first member of the alkaline metal family. It is the first element in the periodic table. The electronegative value of the fluorine atom is higher than that of the potassium atom in the KF molecule. Furthermore, potassium has a one-electron limit since it is the less electronegative element in the KF molecule.

In the KF Lewis structure diagram, the fluorine atom can be the center atom of the molecule. As a result, central fluorine in the KF Lewis structure, with one potassium atom arranged in a linear geometry.

Fluorine accepts one electron and forms a fluoride ion(F-). The total lone pair of electrons in the fluoride ion is eight. They are negatively charged.

Add valence electron around the fluorine atom, as given in the figure.

Step-3: Lewis dot Structure for KF generated from step-1 and step-2

Connect the exterior and core central atom of the KF molecule with one single K-F bond. In this stage, use one potassium atom on the outside of the KF molecule to the central fluorine atom in the middle.

Count how many electrons from the outermost valence shell have been used in the KF structure so far. K-F single bond carries two electrons because the fluorine atom is connected to one potassium atom by K-F single bonds. Bond pairings of K-F are what they’re called.

So, out of the total of 8 valence electrons available for the KF Lewis structure, we used four electrons for the KF molecule’s one K-F single bond. The KF molecule has three lone pairs of electrons in the central fluorine atom.

Place the valence electrons in the K-F bond pair starting with the core fluorine, one potassium atom in the KF molecule. In the KF Lewis structure diagram, we always begin by introducing valence electrons from the central fluorine atom(in step 2). As a result, wrap around the central fluorine atom’s bond pair valence electrons first (see figure for step2).

The fluorine atom in the molecule gets only 8 electrons around its molecular structure. This central fluorine atom is octet stable. But it has three lone pairs. Fluorine gas(F2) is a colorless gas. Fluorine is very corrosive in nature. It is one of the very reactive chemical reagents.

Potassium metal is in a soft solid state at normal temperature and pressure. It is used as a reducing agent in the field of organic chemistry. It is highly flammable in nature. It is very reactive in water and alcohol. Water reacts with potassium metal and forms potassium hydroxide. Similarly, alcohol(such as methanol) reacted with potassium and forms potassium methoxide.

Fluorine requires 8 electrons in its outermost valence shell to complete the molecular octet stability, two electrons bond pairs in one K-F single bond, and three lone pairs in the central fluorine atom. No lone pairs of electrons on the potassium atoms of the KF molecule are placed in a linear geometry. Fluorine already shares 8 electrons to the one K-F single bonds. Then place the valence electron in the potassium atoms, it placed around one electron on each atom(step-1). There are no valence electrons placed around one potassium atom as lone pair of electrons.

We’ve positioned 8 electrons around the one-terminal potassium atoms(step-3), which is represented by a dot, in the KF molecular structure above. The fluorine atom completes its molecular octet stability in the KF molecule because it possesses 2 electrons in its (one K-F single ionic bond pairs) bond pairs with one potassium in the outermost valence shell.

Count how many outermost valence shell electrons have been used so far using the KF Lewis structure. One electron bond pairs are shown as dots in the KF chemical structure, whereas one single bond contains two electrons. The outermost valence shell electrons of the KF molecule(bond pairs) are 2 as a result of the calculation. The total valence electron in a fluorine atom is 8.

So far, we’ve used 8 of the KF Lewis structure’s total 8 outermost valence shell electrons. Three lone pairs of electrons on the fluorine atom in the linear or tetrahedral geometry of the KF molecule.

Complete the middle KF atom stability and, if necessary, apply a covalent bond. The central fluorine atom undergoes octet stability(due to one single bond pair of electrons).

The core atom in the KF Lewis structure is fluorine, which is bonded to the one potassium atom by single bonds (one K-F). With the help of one single bond, it already shares 8 electrons. As a result, the fluorine follows the octet rule and has 8 electrons surrounding it on the one terminal of the KF molecule’s linear or tetrahedral geometry.

How to calculate the formal charge on fluorine and potassium atoms in KF Lewis Structure?

Calculating formal charge on the fluorine of KF molecule:

The formal charge on the KF molecule’s fluorine central atom often corresponds to the actual charge on that fluorine central atom. In the following computation, the formal charge will be calculated on the central fluorine atom of the KF Lewis dot structure.

To calculate the formal charge on the central fluorine atom of the KF molecule by using the following formula:

The formal charge on the fluorine atom of KF molecule= (V. E(F)– L.E(F) – 1/2(B.E))

V.E (F) = Valence electron in a fluorine atom of KF molecule

L.E(F) = Lone pairs of an electron in the fluorine atom of the KF molecule.

B.E = Bond pair electron in Br atom of KF molecule calculation of formal charge on fluorine atom in KF molecule

The fluorine core atom (one single bond connected to one potassium atom) of the KF molecule has seven valence electrons, three lone pairs of electrons(six electrons), and 2 bonding pairing valence electrons. Put these values for the fluorine atom in the formula above.

Formal charge on fluorine atom of KF molecule = (7- 8-(0/2)) = -1

In the Lewis structure of KF, the formal charge on the central fluorine atom is -1 (negative charge).

Calculating formal charge on the potassium atom of KF molecule:

The formal charge on the KF molecule’s potassium terminal atoms often corresponds to the actual charge on that potassium terminal atoms. In the following computation, the formal charge will be calculated on the terminal potassium atom of the KF Lewis dot structure.

To calculate the formal charge on the terminal potassium atom of the KF molecule by using the following formula:

The formal charge on the potassium atom of KF molecule= (V. E(Na)– L.E(Na) – 1/2(B.E))

V.E (K) = Valence electron in a potassium atom of KF molecule

L.E(K) = Lone pairs of an electron in the potassium atom of the KF molecule.

B.E = Bond pair electron in H atom of KF molecule calculation of formal charge on potassium atom in KF molecule

The potassium terminal atoms of the KF molecule have one valence electron, no lone pairs of electrons(zero electrons), and two bonding pairing valence electrons(single bond). Put these values for the potassium atom in the formula above.

Formal charge on potassium atom of KF molecule = (1- 0-(0/2)) =+1

In the Lewis structure of KF, the formal charge on the terminal potassium atom is +1 (positive charge).

Summary:

In this post, we discussed the method to construct the KF Lewis structure. First, the valence electrons are placed around the potassium atom and lose one electron. Then it becomes potassium positive ions. Second, place the valence electron on the fluorine atoms and the fluorine atom accepts one electron in its valence shell. Finally, when we combined the first and second steps. It gives KF Lewis structure. Need to remember that, if you follow the above-said method, you can construct molecular dot structure very easily.