CaH2 Lewis Structure & Characteristics: 17 Complete Facts

CaH2 is an alkaline earth hydride as it comprises calcium from the alkaline metal group and the hydride stands for H2. Let us look for the physical characteristics of CaH2.

Calcium hydride or CaH2 is bonded to two hydrogen atoms via single bonds and has a molecular mass of 42.094 g/mol. It exists as a greyish colour powder form and is vigorously used as a drying agent.

The nature of bonding, hybridization of CaH2, and its respective structure and all other properties associated with CaH2 are explained in the below sections of this article.

How to draw CaH2 lewis structure

The pictorial representation of the bonding electrons in the form of dots is called lewis structure. Let us draw the lewis structure for CaH2 by following the rules given below.

Valence count of electrons for CaH2

The total available valence electrons for CaH2 are 4 as two electrons come from the outer orbitals of the calcium atom and one electron from each hydrogen atom.

The placement of the electropositive atom in the centre

The calcium atom will place in the centre of the structure while hydrogen at the outer sides. This is because calcium has an electronegativity value of 1.1 and hydrogen atom has 2.1. Hence calcium is more electropositive than hydrogen in this way and will occupy the central position.

Sigma rule of bonding

The single sigma bonds will be placed first between the calcium and hydrogen because at first. This is because each atom is a sigma donor in nature and hence firstly bonded singly only then opt for a double bond.

cah2 lewis structure
CaH2 lewis structure

CaH2 lewis structure resonance

The phenomena of resonance found in that system contain unsaturation. Let us observe if the CaH2lewis structure is a full-filling requirement for resonance or not.

  • CaH2 does not exhibit resonance as it does not follow the below requirements
  • It does not have empty orbitals in which electrons can move.
  • There is no presence of double or triple bonds in the structure.

CaH2 lewis structure shape

The structural shape of any molecule tells about the geometrical arrangement of involved atoms within the molecule. Let us go through the shape of the CaH2as given below.

The entity CaH2 adopts an Orthorhombic structural arrangement as characterized by the x-ray diffraction studies. The value of lattice parameters i.e. a, b, and c of this structure are 3.572 Å, 5.901 Å and 6.771 Å respectively and the bond distance between ca and h is  2.24–2.62 Å.

CaH2 lewis structure formal charge

The formal charge represents the total charge carried by the particular molecule and ion. The calculations for the formal charge onCaH2 are given below.

The formal charge on CaH2 is zero as calcium carries a +2 charge and the hydrogen atoms also carry -2. Hence, both the atoms cancel out each other charges and the resultant ion comes out to be zero.

CaH2 lewis structure angle

The structural angle gives information about the distance between the atoms within the molecule. The value for the angles in CaH2is given below.

The magnitude of the angle for CaH2 is 900. This happens because CaH2has opted for an orthorhombic arrangement and the value of angles i.e. alpha, beta and gamma are equal to each other.

CaH2 lewis structure octet rule

The octet rule explains why the atoms after bonding become more stable. Let us check if CaH2 is also attained stability as per this rule.

The calcium hydride follows the octet rule. This is because after bonding calcium attained a stable noble gas configuration and also the s orbitals of the hydrogen atoms also get fulfilled. Hence CaH2 attained more stability after the bonding.

CaH2lewis structure lone pairs

The electron pairs which present next to the bonding pairs but do not participate in the bond formation directly are known as lone pairs. Let us look for CaH2.

The number of lone pairs associated with CaH2 is zero. This is because after the bonding between the calcium and hydrogen, can carry 2+ charge and are left with no electrons which can behave as lone pairs

CaH2valence electrons

The electrons that are present in the outermost shell of the orbitals and can participate in bond formation are called valence electrons. The valence count for CaH2 is given below.

The number of valence counts for calcium is 2 as well as for hydrogen also. This is because the electronic configuration of the calcium is [Ar] 4s² and the hydrogen atom has 1s1. According to the valence electron definition, electrons present in the outermost core are considered to be valence electrons.

CaH2 hybridization

The concept of hybridization is used to explain the molecules formed via covalent bonding. Let us see how this term related to the CaH2.

There is no assigning of hybridization to CaH2. This is because it is an ionic compound and hybridization can be explained for covalent compounds. Moreover, in ionic molecules, the bond is formed via electrostatic attractions between the positive ion like Ca2+ and a negative ion like H in the case of CaH2.

Is CaH2 solid?

If the intended compound has adequate shape and volume then it belongs to the solid state of the matter. The given paragraph explains if cha2 is solid or not.

CaH2 belongs to the solid state of matter. This is because CaH2 has a melting point of 8160c and only solids have melting points whereas the liquid has boiling point only. Furthermore, the conformation for the existence of the solid structure of CaH2 is also done from the X-ray diffraction studies.

Is CaH2 soluble in water?

The term solubility explains which solvent is perfect for the given molecule. Let us observe whether the water as a solvent is suitable for CaH2 or not.

CaH2 is soluble in water. This happens because CaH2 is formed via ionic bonds. Ions of opposite sign formed when ionic bonds break inside the water molecules. These resultant ions interact with the the ions of water molecules and led to form new bonds.

How and why CaH2is soluble in water?

CaH2 is soluble because it reacts with water vigorously and liberates hydrogen gas. The formation of hydrogen gas enhances the entropy of the reaction as given:  CaH2  ​ +   2H2​O→    Ca(OH)2  ​+  2H2​.

Is CaH2 polar or nonpolar?

The polarity and non-polarity of CaH2  depend upon the fact that the given structure is symmetrical or not.  Let us look for CaH2.

CaH2 is polar. It is soluble in polar solvents like water. As per the rule “like dissolving like” since water is polar and CaH2   is soluble in water. It refers to the polar nature of CaH2. Moreover, all the ionic compounds are always polar in nature.

Is CaH2  a molecular compound?

A molecular compound refers to the chemical entity which contains two types of atoms within. Let us see if CaH2  belongs to this category or not.

CaH2  is a molecular compound. as it contains 3 atoms of a different kind.

Is CaH2 acid or base?

Any chemical entity which enhances the proton and  OH  concentration refers to acid and base respectively. The explanations for the acidic and basic nature of CaH2  are given below.

CaH2 is a base. when it reacts with water molecules it abstracts the hydrogen atom of the H2O and in this way reduces the H+ concentration of the solution. Hence, this way it indirectly somewhat makes the reaction mixture more basic.

Is CaH2  electrolyte?

When the given compound completely dissolves in the solution and produces free electrons to generate electricity is called an electrolyte. Let us look for CaH2 .

CaH2  is a good electrolyte because in CaH2 atoms are held together via ionic bonds. Due to the presence of these ionic bonds electrostatic interaction behind the ions i.e. Ca2+ and H2- are responsible for this.

Is CaH2 salt?

A salt is any chemical entity which contains an anion and cation in its framework. Let us find out if CaH2  is salt or not.

CaH2 is a salt because it justifies the definition of salt and contains both parts. The cation part refers to Ca2+ and anion belongs to H2-. Generally, all the ionic compounds are salt in general.

Is CaH2  ionic or covalent?

The molecules which are formed by the mutual sharing of electrons are considered covalent while others are ionic. Let us look for CaH2  .

CaH2 is ionic. The calcium atom in CaH2 donates its two electrons from its 4s orbital then the atom carries itself a positive charge of +2. Likewise, hydrogen carries to 2 to maintain neutrality. Hence, in this way ions are generated.

It is formed by the complete transfer of electrons from the calcium atom to the hydrogen atoms which accept those electrons during the procedure of bonding.


CaH2   belongs to the basic category of hydride and carries zero formal charges. CaH is also known as hydrolith as it liberates hydrogen gas.

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