Chemical bonds-Types and Definition
Chemical bonds – Definition
Chemical bonds are attractions between two atoms, ions or molecules that enables formation of chemical compounds.
A stable compound occurs when the total energy of the combination has lower energy than the separated atoms.
Types of chemical bonds
Chemical bonds are divided into two main types.
- Electrovalent or ionic bonds.
- Covalent or bonds.
Electrovalent (ionic) bonds
Electrovalent ( ionic ) bonds are chemical combinations which involves the transfer of valence electrons ( valence electrons are those electrons that can be found in the outermost shell of the atom ) from a donor atom to an acceptor atom.
The donor atom is usually always metallic and the acceptor non-metallic.
The donor atom normally has a valency of one or two electrons making it highly reactive this allows them to easily give up those electrons to attain a stable octet or duplet state, Examples are alkali metals like sodium and potassium.
And also the atom which accepts the electrons exist in a very reactive state with valence electrons of usually seven, an example of this is Flourine and
With a valence electrons of seven it needs only one more electron to achieve a stable octet state so it’s bound to attract any atom close to it .
In Electrovalent reactions, after electron transfer the Donor of the electrons acquires a positive charge and the acceptor acquires a negative charge
These charged particles are known as ions. Ionic reactions can be explained using Lewis diagrams.
Examples of an ionic reaction
Characteristics of ionic compounds
- They have high melting and boiling points.
- Most ionic compounds readily dissolve in water.
- The combination doesn’t affect the character of the individual atom.
- They consist of negative and positive ions.
- They form three dimensional crystal lattices.
Covalent bonds are further divided into two other types namely;
- Ordinary covalent bonds
- And coordinate ( dative ) covalent bonds.
Ordinary covalent bonds are chemical combinations which involves the sharing of a pair of electrons between two reacting atoms.
In Ordinary covalent reactions an electron from the outermost shell of each atom is contributed to the reaction, sometimes more than one electron is contributed to the reaction.
In covalent bonding the bonded atoms are regarded as molecules and form Diatomic molecules, Examples are the organic molecules formed by this method.
Conventionally, the shared pair is is represented by a stroke between the two atoms in the association. E.g H-H and Cl-Cl.
Coordinate or dative covalent bonds are a type of covalent bond which involves sharing the electrons between atoms
But unlike the ordinary covalent bond the electrons are contributed by only one of the atoms, these electrons are identified as the lone pair so
In each Dative covalent bond a lone pair must be involved in the reaction.
Examples of atoms which undergo dative covalent bonds are Ammonia and Water.