Interatomic bonding: Ionic and covalent bonds

Continuation of Chemical bonding

INTERATOMIC BONDING

Interatomic bond is a type of bonds that occurs between two atom, it responsible for the binding together atoms to form molecules or compound.

TYPES OF INTERATOMICS BOND

1. Electrovalent/ionic bond

2. Covalent bond

3. Dative bonds/ Coordiante covalent bonds

4. Mettalic bonds.

ELECTROVALENT / IONIC BOND

Electrovalent which also known as ionic it is type of bonding that involve the transfer of electron from one atom to another so as to attained the dublet or octet configuration of noble gases

It formed between atom which have a large difference of elctronegative that involve the transfers of electron from less electronegative to more Electronegative atom.

It can also be define as a type of bond that occurs between metals and non metals.

Condition for the formation of electrovalent bonds

1. The two atom must be metal and non metal.

2. The electronegative difference between them must be large that is the metal must carry 1,2 and 3 valence and the non-metal must have 5, 6, and 7 valence electron in the outermost shell.

3. One atom must donate it’s excess electron and become positively charge (cation) to another atom that need more electron to become negatively charge so the both can acquire stable

Properties of Ionic or elctrovalent compound.
  1. They are soluble in water and others polar solvents and not soluble in non-polar solvents such petrol, turpentine, kerosene, benzene etc
  2. They have high melting and boiling point.
  3. In aqueous solution they are conduct an electric current using free mobile ion as carrier I.e they are electrolyte
  4. They are hard.
Example of electrovalent/Ionic compound

Example of elctrovalent compounds are.

The reaction between sodium Na (metal) and chlorine Cl (non-metal)  to produce Sodium chloride NaCl (salt)

Na+   +  Cl-   —-> NaCl

Na –> 2, 8, 1——–|
                            |———> reactant 
Cl –> 2, 8, 7.____ |

There will be transfer of electron from sodium to chlorine so they can both acquire noble gase configuration of 2,8 and 2, 8, 8, respectively.

Na –> 2, 8 ——-|
                         |———> product 
Cl –> 2, 8,8,.___|

Nacl bonding (Getty image)

Other examples are.

NaoH, Na2F, Cacl2, CaO, CuSo4, BaCl2.

COVALENT BOND

Covalent bond is a type of bonds that occurs between non-metal to non-metal it involves the sharing of electron in their outermost shell to attain the Nobel Gase configuration.

Covalent bond which also known as molecular bonding involved the sharing of pairs electron in the outermost shell between atom of an element.

Covalent atoms do not become normal negative charge or positive charge since no transfer of an electron from one atom to another,  which implies that no ions are formed in covalent bonding.

Condition necessary for the formation of covalent bond

1. There must always be sharing of pairs of electron between the atoms.

2. Atoms must have zero or very small electronegative difference

3. The formation of covalent bond requires atom to have odds or unpaired electron in the outermost shell.

Note. The number of unpaired electrons in the outermost shell of an atoms indicates the maximum number of covalent bonds that can be formed by the atom.

Types of covalent bonds

Covalent bonds can be classified into three.

  1. Single covalent bond
  2. Double covalent bond
  3. Triple covalent bond
Single Covalent bond

This is a type of covalent bond in which only one pair of electrons is shared between atoms.

Example.

HCL the bond that exist between HCl is single covalent bond

H2  + Cl2 — 2HCl

H — 1

Cl  —> 2, 8, 7

They both need one to acquire the duplet and octet configuration of noble gases so they will share, chlorine will share one with hydrogen, hydrogen will also share

When they share they share only one electron which exist as H—-Cl

single covalent bond in HCl (Getty image)
Double Covalent bonds

When two atoms shared two pairs of electron between them rather than one it called double covalent bond.

Double covalent bond is more stronger than single covalent bond in example are

The reaction between two oxygen atoms to form molecules

O — 2, 6

O — 2, 6

The two atoms need two electron go attained the octet configuration of noble gases so they will share two electron between themselves and become O = O

Triple Covalent bond

Triple covalent bond requires two atoms sharing three electron between themselves to Attained the octet configuration of noble gases

Example is

The reaction between two Nitrogen atoms to form a molecules.

N — 2, 5

N — 2, 5

The two atoms need  three electron to attained the octet configuration of noble gases so they will share three electron between themselves and become N = + –N

Others example are acetylene, carbon monoxide, cyanide ion

Properties of Covalent bond
  1. They are insoluble in polar solvent and soluble in non-polar solvent.
  2. They are brittle
  3. They have low melting and boiling point
  4. They do not conduct else electricity in molten state, they are non-conductor
                            
  5. They are gases or a volatile liquid.

Co-ordinate covalent bond

This type of bond requires two atoms in which one donate electron and the others atoms share for the purpose of attaining the configuration of noble gases it special covalent bond.

Co-ordinate covalent bond which also known as dative bond can also be used in joining protons to neutral covalent molecules example ammonium ion and hydroxonium ion.

In Dative bond the donor carries positive charge while acceptor carry negative charge

            A: + B ——–>  A+ —–B-

Metallic bond

It is type of bond that join metal with metal and metal with their alloys, most of the physical properties of metals such as melting and boiling point, ductility, thermal conductivity, lustre are all result from the metallic bonds between the metals.

The condition for the formation of metallic bonds are.

  • There must large number of electrons in the valence shell of metals.
  • There must be large atomic radius.
  • It can be attained by low ionization.

Lesson key points

1. Ionic bond which also know as electrovalent bond can be formed between two atom of opposite charge.

2. Covalent bond involve sharing of electron between an atom.

3. Molecules and not ions is formed between the atoms of covalent bond.

4. Covalent bond can be polar eg HCl while some are non-polar eg CO

5. Ionic compound are not conductor of electricity at solid state except at molten or solution state

6. Ammonium chloride contains an ionic bond NH4+ and Cl- within NH4+ , there are three covalent bonds and one dative bond. Therefore there are three interatomic bonds in the compound.

7. The boiling point of metal is a result of metallic bonds and it more larger than the melting point.

8. Boiling point requires more energy than melting point because it requires much energy to break all the metallic bonds between metals.

CHEMICAL BONDING

INTERMOLECULAR BOND AND THE TYPES

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