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,.___|
Other examples are.
NaoH, Na2F, Cacl2, CaO, CuSo4, BaCl2.
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.
Single covalent bond
Double covalent bond
Triple covalent bond
Single Covalent bond
This is a type of covalent bond in which only one pair of electrons is shared between atoms.
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
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
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
They are insoluble in polar solvent and soluble in non-polar solvent.
They are brittle
They have low melting and boiling point
They do not conduct else electricity in molten state, they are non-conductor
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-
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.
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