CaCl2 Lewis structure, Molecular geometry, Hybridization

Calcium Chloride (CaCl2) is an organic compound. It is also called calcium dichloride or calcium chloride anhydrous. It is an ionic compound. It is composed of calcium and chlorine. It is crystalline solid white in color at room temperature. It is highly soluble in water. So, it is hygroscopic in nature. Because of its hygroscopic nature, it must be kept in a tightly-closed container. It has a very high enthalpy change of solution. It is odorless.

 

Calcium chloride is a very important industry as well as healthy life. It is useful as a food preservative, for de-icing roads, in winters. It is used in water treatment plants. It has many applications in oil-well drilling, metallurgy, rubber, dye, paper, and paint industries. We can use it in self-heating cans and heating pads. It can be used as a sterilant for male animals.

Calcium Chloride is considered to be an important mineral that can help our bodies to function properly and naturally. It is used in swimming pools as a form of water. It keeps the fruits and vegetables fresh. It also prevents decay. Besides this, it is disadvantageous. It is an irritating compound. It is required to be handled with gloves. 

The chemical formula of calcium chloride is CaCl2.

Properties of CaCl2

• It is an odorless white powder.
• The density of CaCl2 is 2.15g/ml.
• The melting point is 772°C and the boiling point is 1935°C.
• It is highly water-soluble. So, it is hygroscopic.
• Its molecular mass is 110.98g/mol.
• Its IUPAC name is calcium chloride.

Molecule name	Calcium chloride
Chemical notation	CaCl2
Valence electrons	16
Molecular geometry of CaCl2	Linear
Electron geometry of CaCl2	Linear
Hybridization	sp type
CaCl2 Bond angle	180°
Is CaCl2 Polar or Nonpolar?	Ionic Nonpolar

CaCl2 Lewis Structure

Gilbert N. Lewis developed a diagrammatic method for representing a molecule its chemical bonds, and a lone pair of electrons, known as the Lewis or electron dot structure. The Lewis structure also shows the total number of lone and bound pairs of electrons in the atom. The Lewis structure only considers the electrons in the valence shell of a molecule, ignoring the interior shells. In a Lewis structure, a dot represents a lone pair of electrons, whereas a straight line represents a bonded pair of electrons.

 

Calcium Chloride consists of two kinds of elements, i.e. Calcium and Chlorine. There is one calcium atom and two chlorine atoms in a calcium chloride molecule as the name suggests. In this molecule, calcium behaves as the central atom. It is because Calcium is less electronegative than Chlorine and we know the lesser the electronegativity value of an element the more likely it is to behave as a central atom. Thus, two chlorine atoms are bonded to a central calcium atom.

Valence Electrons

The total number of electrons present on the outermost shell of an atom is called valence electrons. Only the valence electrons take part in any chemical bond formation. They are either transferred or shared (completely or partially) for the bond formation. Calcium has four electrons on the outermost shell. Hence, the total number of valence electrons on calcium is four. Similarly, chlorine has seven electrons on the outermost shell thus making the number of valence electrons of chlorine seven.

Octet Rule

The urgency or tendency of each atom to have 8 electrons on its valence shell by losing, acquiring, or sharing electrons is known as the octet rule. The atoms acquire the electronic configuration of the nearest noble gas by gaining, losing, or sharing electrons. Except for hydrogen and helium, all elements follow the octet rule. (The duplet rule applies to hydrogen and helium.)

Formal Charge

Formal charge can be defined as the difference between the number of valence electrons in the neutral atom and the number of valence electrons around the atom in the molecule. When formal charge of an atom is less, the stability of the Lewis diagram is higher.

Formal charge can be calculated using a formula:

Formal Charge (FC) = V – N – B/2 Where,

V= Number of Valence Electrons

N = Number of nonbonded electrons

B = Number of bonded electrons

Steps for drawing Lewis Dot structure of CaCl2

Step 1: In the first step, Count all valence electrons present in CaCl2. For finding valence electrons simply remember the periodic table group.

As calcium lies in the 2nd   group, the valence electron is 2.

Similarly, chlorine is located in the 17th  group, and the valence electron is 7.

Total valence electrons for CaCl2 to draw lewis structure,

CaCl2 = 2+(7*2)=16 valence electrons.

Step 2: Since we know that calcium chloride is not a covalent bond. We cannot write the proper Lewis structure that we make a molecule. As we know calcium chloride is an ionic compound in which calcium is metal and chlorine is non-metal. Calcium has 2 valence electrons and chlorine has 7 valence electrons. So, calcium donates one electron in each two chlorine atoms. In this way, CaCl2 completes the octet rule.

Step 3: Calculate the formal charge distribution on all atoms and check the stability

The formal charge of all the atoms is calculated to check the stability. The formula to calculate formal charge distribution is:

Formal charge (FC) = [Valence electrons (V) – Lone pair electrons (L) – Bonded pair electrons (B)/2]

Charge of Calcium in CaCl2 ​= +2

So, Calcium ion exists as Ca2+, and chlorine ion exists as Cl−, so it becomes a CaCl2 molecule.

CaCl2 Molecular Geometry and Shape

The three-dimensional arrangement of the atoms that make up a molecule is referred to as molecular geometry. The molecular geometry of every molecule is crucial because it provides information on many physical and chemical properties of the compound, including polarity, reactivity, phase of matter, color, magnetism, biological activities, and so on.

 

The CaCl2 molecule has a linear shape. Calcium Chloride molecule has two Ca – Cl bonds and zero lone pair.

We can also determine the geometry and shape of the CaCl2 molecule using the VSEPR theory. For this, we can use the AXN method.

AXN Notation for CaCl2 molecule:

1. A represents the central atom, In the CaCl2 molecule, the central atom is Calcium. So, A = Calcium
2.  X represents the bonded atoms to the central atom. In CaCl2 molecule, 2 chlorine atoms are bonded to the central atom Calcium. So, X = 2
3.  N represents a lone pair of electrons on a central atom. The central atom Phosphorus has zero lone pair of electrons.

 So the AXN generic formula for CaCl2 becomes AX2N.

According to VSEPR theory, if the molecule has an AX2N formula then the molecule has linear molecular geometry and linear electron geometry.

 

CaCl2 Hybridization

Calcium chloride(CaCl2) has sp2 hybridization as it has two sigma bonds (Ca – Cl) and zero lone pair of electrons on the central atom Calcium. The steric number is 2 which indicates sp hybridization.

We can also calculate hybridization with the use of the following method:

1. If the total number of valence electrons of the molecule is less than 8, divide it by 2.
2. If the total number of valence electrons of the molecule is greater than 8 and less than 56, divide it by 8. Then divide the remainder by 2. Add the two quotients to get the number of orbitals.
3. If the total number of valence electrons of the molecule is greater than 56, divide it by 18. Then divide the remainder by 2. Add the two quotients to get the number of orbitals.

Calcium chloride(CaCl2) has a total of 16 valence electrons. So, We will use the second step of the above-mentioned method.

Dividing 16 by 8 we get quotient 2 and reminder 0. Again dividing the remainder 0 by 2 we get quotient 0.

Finally adding the two quotients i.e. 2 + 0, we get 2.

The number of orbitals is equal to 2. Hence, the hybridization in the Calcium Chloride(CaCl2)  molecule is sp.

CaCl2 Bond Angle

Calcium Chloride has a bond angle of 180°. Calcium chloride molecule has two electrons rich regions (two Ca– Cl bonds and zero lone pair of electrons on central Ca atom). These two electrons dense regions make the geometry of the CaCl2 molecule linear and hence the bond angle of 180° formed.

Is CaCl2 Polar or Nonpolar?

The polarity of a molecule is determined by its dipole moment. A dipole moment is given by the product of the magnitude of the charges and the distance between the center of positive and negative charges. A dipole moment is generated when the molecule has an asymmetrical arrangement of the atoms surrounding the central atom. As we know, CaCl2 is an ionic compound composed of metals and non-metals. Calcium is metal and chlorine is non-metal. So there cannot be sharing of electrons but calcium can donate electrons in each two chlorine atoms. Therefore, the polarity of CaCl2 is nonpolar. 

Summary