KF is an alkali halide molecule and source of fluoride extraction from minerals Let us explain in brief the KNO3 lewis structure and the other 11 facts in brief below.
KF is a more ionic compound rather than covalent nature. K is an alkali molecule whereas F is a halogen so there is a strong ionic interaction occurred between K-F bonds. KF adopts a cubic lattice structure like NaCl. Both atoms are monovalent in the KF molecule. K donates one electron and F accepts that.
The KF molecule is consist of two atoms only, so we cannot differentiate the central atom but K plays the central atom role. K and F share a single bond. Let us focus on some important facts about KF like lewis structure, valence electrons, and hybridization in the following section with proper explanations.
How to draw the KF lewis structure?
Lewis structure can predict the molecular shape, bond angle, and valence electrons of a particular atom. Now discuss how to draw the lewis structure of KF in a few steps.
Counting the valence electrons –
We need to first calculate the total valence electrons which are involved in the bond formation of the KF molecule. The valence electron of K is 1 and for F is 7. So, now we add both the valence electrons to get the total valence electrons. So, the total valence electrons for the KF molecule is 7+1 = 8.
Choosing the central atom –
As the KF molecule consists of two atoms so it’s difficult to differentiate between the central atom and terminal atom. But based on the size and electropositivity we choose K as the central atom and F as the terminal atom, although the molecule is linear concerning both atoms.
Satisfying the octet –
After successive bond formation, we have to check whether both atoms are satisfied by the octet rule or not. K and F both need one more electron in their valence orbital to complete their octet. So, we need 2+8 =10 electrons for octet, and there are 8 valence electrons are present in the KF molecule.
Satisfying the valency of every atom –
In the last section, we see that there are 10-8 = 2 electrons that are short for completing the octet of the K and F atoms. Now, these 2 electrons are satisfied by the 2/2 = 1 bond. K and f both are monovalent and both shares one bond in between them to satisfy their valency as well as an octet.
Assign the lone pairs –
After satisfying the octet and valency if there are extra non-bonded electrons present for any atom then they will be assigned as lone pairs over that particular atom. K has no extra electron but F has extra six electrons after bond formation. Those six electrons are assigned as lone pairs over the F atom.
KF lewis structure shape
KF lewis structure shape is the particular shape where K and F make after the formation of a bond. Here we discussed the actual shape of KF in detail.
The molecular shape of KF is linear concerning both atoms. As the structure is linear so there are two terminal atoms present one is K and the other is F. This linear geometry is also maintained by the single bond between both atoms. But if we see the lattice structure that is cubic for KF.
The reason behind the linear geometry is the maintain the low steric repulsion and it is the perfect geometry for two atoms can make. There is no other option is present for geometry, also there is no lone pairs repulsion so the shape does not deviate from its linearity. That’s whys it adopts linearity.
KF valence electrons
Valence electrons are those electrons present in the valence orbital of every atom and involved in the bond formation. Let us count the valence electrons for the KF.
The total valence electrons for KF are 8. Among these 1 from K and other and the rest of 7 from F. The electronic configuration of K is [Ar]4s1 and for F is [He]2s22p5. For K 4s is its valence orbital and for F 2s and 2p. So, electrons present in those orbitals are considered valence electrons.
Now calculate the overall valence electrons for the KF molecule
- The valence electron for K is = 1
- The valence electrons for F are = 7
- So, the total number of valence electrons for the KF molecule is 7+1 = 8
- Total valence electrons for KF are the summation of individual valence electrons for K and F.
KF lewis structure lone pairs
Lone pairs the valence electrons and is present also in the valence orbital but do not participate in the bond formation. Let’s see which atom can contain lone pairs.
The lone pairs of KF molecules are six pairs. Which comes from the F site. K is lack lone pairs because it does not contain enough electrons that can assign as lone pairs after bond formation. But F has excess electrons which can exist as lone pairs after bond formation. They are non-bonded electrons.
Now calculate the lone pairs of every atom in the KF molecule by using a formula,
- lone pairs = valence electrons – bonded electrons
- Lone pairs of K is, 1-1 = 0
- Lone pairs of F is, 7-1 = 6
- So, the overall lone pairs of KF molecule is 6.
F lone pairs are the lone pairs of KF.
KF lewis structure formal charge
The formal charge can predict the charge over a particular atom in a molecule. Let’s calculate the formal charge of the KF molecule to see whether it is charged or not.
The formal charge of KF is zero. So, there is no charge present neither on K nor on F. K and F are bonded by covalent bonds rather than ionic interaction. Both are monovalent atoms, so the amount of positive K is neutralized by the amount of negative charge over F.
The formula being used for the formal charge is,
- F.C. = Nv – Nl.p. -1/2 Nb.p.
- The formal charge over K is 1-0-(2/2) = 0
- The formal charge over F is 7-6-(2/2) = 0
- So, the overall formal charge of the KF molecule is zero.
- This also proves that the KF molecule is neutral and no charge appears on it.
KF lewis structure angle
The bond angle of a molecule is a particular angle that forms by the particular orientation of the toms present within the molecule. Now discuss the KF bond angle in detail.
The bond angle of the KF molecule is 1800. This proves that the orientation of the K and F atoms is linear and there is no deviation in their arrangement. They are simply connected via a single bond and lie in the terminal position of the single bond. So, they adopt linear geometry and bond angle 1800.
1800 is the ideal bond angle for the linear molecule. So, from the bond angle data, we can say that there is no deviation factor present within the molecule. If there is any kind of steric repulsion present then the molecule tries to minimize that kind of repulsion via changing the bond angle.
KF lewis structure octet rule
Every covalent or ionic molecule obeys the octet rule by completing the valence orbital of atoms via sharing electrons. Let us see how the KF molecule obeys the octet.
K releases one electron from its s orbital and completes its octet. Now that released electron was accepted by the F in its valence shell. So, now F also completes its octet as F has seven electrons in its valence orbital after accepting its valence orbital filled like a noble gas.
The electronic configuration of K is [Ar]4s1, so when it releases one electron from its 4s orbital which is the valence orbital then its configuration becomes noble gas like Ar. Again, for F the electronic configuration is [He]2s22p5. By accepting one electron its octet is also complete.
KF lewis structure resonance
Delocalization of electrons clouds from one skeleton form to another with excess electron density is called resonance. Let’s see whether resonance occurred in KF or not.
There is no resonance occurred in the KF molecule. Because KF is an ionic molecule and there are no shares of electron density between two atoms. K donates electron and F accepts. There is also no presence of excess electron density. Here total transfers of electron density occurred.
Resonance was only observed in the covalent molecule. Where two or many more atoms share electron density via bonds. Also, if there presence of any excess electron clouds then only that electron clouds are delocalized via transferring the sigma bonds of the molecule. But not occur in ionic compounds.
KF hybridization
KF is sp hybridized. This value of hybridization also inters its linear geometry. We can predict the hybridization of KF from the below table from its geometry.
| Structure | Hybridization value | State of hybridization of central atom | Bond angle |
| Linear | 2 | sp /sd / pd | 1800 |
| Planner trigonal | 3 | sp2 | 1200 |
| Tetrahedral | 4 | sd3/ sp3 | 109.50 |
| Trigonal bipyramidal | 5 | sp3d/dsp3 | 900 (axial), 1200(equatorial) |
| Octahedral | 6 | sp3d2/ d2sp3 | 900 |
| Pentagonal bipyramidal | 7 | sp3d3/d3sp3 | 900,720 |
The s orbital of K and p orbital of F undergo form sp hybridization. As KF is ionic so we cannot calculate the hybridization by the convention formula, H = 0.5(V+M-C+A), where H= hybridization value, V is the number of valence electrons in the central atom, and M = monovalent atoms surrounded.
Is KF ionic or covalent?
According to Fajan’s rule, no compound is pure ionic or covalent in nature, every molecule has some of both characteristics. Now see whether KF is ionic or covalent.
KF is an ionic molecule rather than a covalent molecule. Because here no shares of electrons occurred during the bond formation. K donates one electron and F accepts that electron to form an ionic bond.
Why and How KF is ionic?
Ionic molecules always form during the total donation of electrons from one species to another species. No sharing of electrons in the bond occurred in the ionic bond.
KF can be totally ionized to form K+ and F-. So, here total charge separation can be possible and it is a sign that the KF bond is purely an ionic bond otherwise total charge separation is not possible. So, the K-F bond is pure ionic and KF is an ionic molecule and also ionic potential of K is very high.
Ionic or covalent nature also depends on the ionic potential of the cation and the polarizability of the anion. The ionic potential of K is high but the polarizability of F is very low. As the ionic size of F is very low so it cannot be polarized by the high electronic charge density.
Is KF an acid or base?
The species that releases H+ ion is called acid and those that release OH– are called the base. Let’s see if KF is acid or base.
KF is neither an acid nor a base. KF is made by the reaction of a strong base and weak acid, so we can say that there is a basic character present within the molecule. Rather it is a basic salt. The pH range of KF lies between 5.5 to 8. So, it is a very wide range. So, it’s difficult to say its acidity.
Why and How KF is weak basic?
KF is neither acidic nor basic but it is slightly basic, rather it is weakly basic. Now understand how KF is acting as a weak base.
KF is made upon the reaction of a strong base like KOH and weak acid like HF. So, when they formed KF then there is some basic character will exist as it comes from a strong base. The product not be neutralized properly due to the difference in acidity. that’s why it behaves as a weak base.
Any acid-base reaction always not be neutralized. The acidic or basic nature of the final product depends on the initial acid or base. If both are the same then the final product will be neutralized otherwise which is strong, its character will be observed in the final product.
Is KF soluble in water?
A molecule that is soluble in water is dependent on how it dissolved in water by breaking its bond. Let’s see if KF is soluble in water or not.
KF is water soluble. Because it is an ionic salt and breaks its bond very quickly in water and gets dissolved into it. The hydration energy of K+ is so high that it attracted the water molecule surrounding it and is dissolved in the water.
Why and How KF is soluble in water?
KF is an ionic salt, so it is dissolved in water and get dissociates into two different ions, and is soluble in water.
KF is ionized to form K+ and F– in the water solution and the hydration energy of K+ is very very high. So, it attracted the water molecules in very large amounts and water molecules surrounded the cation and gets soluble in the cation. The same also occurred for the anion.
Not all the salt dissolved in the water because some salt has a very high hydration enthalpy, then it requires higher energy to break its bonds to soluble in water. But KF needs very less energy to be soluble in water even though its hydration energy is enough for this task.
Is KF a strong base?
Higher the tendency to release OH– higher will be the basicity of that species. Now see the tendency of absorbing the proton of the KF molecule.
KF is not a strong base, because its ability to abstract protons from the acid molecule is very low. Also, KF is formed by the reaction of a strong base and weak acid. So, its basic nature is very low. KF is basic salt rather than a weak base.
Why and How KF is not a strong base?
KF is weak base salt, due to the formation of a reaction with a strong base and weak acid.
When a strong base reacts with weak acid then the product is not fully neutralized. The character of the base always dominates there. KF is formed by the reaction of a strong base and weak acid. Weak acid cannot be neutralized the strong base and the product has some basic nature but is very weak.
KF is a basic salt rather than a base. So, we cannot say that it is basic or acts as a weak base, or reacts with acid. KF is not used as a base in the acid-base reaction. It is just a basic salt.
Is KF a salt?
Reaction with acid and base formed water molecule along with salt. Salt is an ionic compound formed with cation and anion. Let’s see if KF is salt or not.
KF is an ionic salt. It formed with K+ cation and F– anion with proper lattice structure. KF is also formed by the reaction of a strong base like potassium hydroxide and weak acid like hydrogen fluoride. Naturally, KF has weak basic properties because not for full neutralization.
Why and how KF is an ionic salt?
Ionic salt is formed by the reaction of acid and base and ionized fully when it gets dissolved in an aqueous solution and also has a particular lattice structure.
KF is an ionic salt because it has a particular lattice shape, which is cubic. Also, KF is ionized to form two charged particles when it gets dissolved in water. KF is formed upon the reaction of acid and base molecule, which confirmed that KF is a salt and the nature of the salt is ionic.
KF is ionic salt and the nature of the salt is slightly basic. The reaction of acid and base makes the molecule salt. KF is an ionic salt having a lattice structure cubic.
Is KF an electrolyte?
Electrolytes are those species that are ionized in the aqueous solution and conduct electricity in a very easy way. Now we see whether KF acts as an electrolyte or not.
KF is an electrolyte because it is an ionic salt and ionized in the aqueous solution in a very easy way. When an aqueous solution of KF passes the electricity due to the formation of cation and anion with high charge density. So, it can behave as an electrolyte.
Why and How KF is an electrolyte?
KF can be ionized in the aqueous solution and formed ionic particles to pass the electricity, so it is an electrolyte.
KF is being an ionic salt, so when is dissolved in water then it gets dissociates by the hydration energy and formation of two charged particles, one is K cation and the other is F anion. That charge particle is a very good conductor of electricity due to its high charge density.
The aqueous solution of KF passes electricity. So, the whole solution becomes charged when KF is present within. So, in many reactions where electrolyte solution is needed there, KF can be used.
Is KF a strong electrolyte?
Strong electrolytes are those that are dissociated in an aqueous solution very fast and ionic conductance will be high. Let us discuss the electrolytic nature of KF.
KF is a strong electrolyte due to the very fast dissociation of the KF molecule in the aqueous solution to the respective ion. The conductance of the KF solution is also high due to strong ion formation.
Why and How KF is a strong electrolyte?
The formation of strong ion and the fast dissociation of the KF makes a strong electrolyte.
The mobility of the K+ ion and F– ion is very fast. Those two ions are formed due to the dissociation of the KF in an aqueous solution. Due to the formation of those two ions, the electrical conductance is also very high.
The higher the mobility of the ions, the higher will be the interaction occurs and the higher will be the conductance.
Is KF capable of hydrogen bonding?
The smaller size and higher electronegative atoms can interact with the hydrogen atom to form hydrogen bonding. Now see whether KF is capable of H bonding or not.
KF is capable of hydrogen bonding, as KF contains an electronegative F atom. Which is also smaller in size for the formation of an ideal hydrogen bond.
Why and How KF can form hydrogen bonding?
KF has an electronegative F atom, which can form hydrogen bonding.
When KF is coming in close proximity to any hydrogen-containing molecule like water, then there will be a very weak interaction occurring between the hydrogen atom and the F atom of KF. So, hydrogen bonding occurred in the KF by the F site only.
Electropositive K ion is repel the hydrogen atom as both contain the same charge, only F attracted by the hydrogen bonding. Due to the hydrogen bonding many physical, as well as chemical characteristics of the KF, will be changed.
Is KF neutral?
Neutral is defined when the two opposite charges fully cancel out each other. Now we talking about whether KF is neutral or not.
KF is a neutral molecule because the ionic charge present in this molecule is fully neutralized by both exact amounts.
Why and How KF is neutral?
There is no charge present over the KF molecule which makes KF neutral.
When KF is ionized then two ions are formed one is K+ and another is F–. Both are monovalent ions, so the amount of charge is the same but opposite which can be canceled out.
Although KF is neutral it is a basic salt by its basic character.
Is KF nonpolar or polar?
Polarity depends on the nature of the bond or the presence of a permanent dipole moment. Now we have to discuss in brief KF polarity.
The ionic bond present in the KF molecule makes the molecule polar. There is a huge electronegativity difference between K and F atoms so there will be a dipole-moment present.
Why and How KF is polar?
The electronegativity difference between two atoms in the KF molecule makes the molecule polar.
The bond between K and F is polar. There is a dipole-moment flow from the K site to the electronegative F site. So, the bond between K and F is polar. Also, the ionic bonds are always polar and the dipole-moment value is not canceled out for the atoms.
Ionic bond and donation of electrons fully make the molecule polar and for this reason, KF is also soluble in water.
Conclusion
KF is an ionic and basic salt which is consist of K and F. the lattice structure is cubic and the molecule is formed upon the reaction of a strong base and weak acid.
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Hi……I am Biswarup Chandra Dey, I have completed my Master’s in Chemistry from the Central University of Punjab. My area of specialization is Inorganic Chemistry. Chemistry is not all about reading line by line and memorizing, it is a concept to understand in an easy way and here I am sharing with you the concept about chemistry which I learn because knowledge is worth to share it.
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