Definition of Covalent Bonds According to Experts
A covalent bond is a bond that occurs due to the use of two electron pairs together by two atoms (James E. Brady, 1990). A covalent bond is formed between two atoms that both want to capture electrons (fellow non-metal atoms).
The electron pairs used together are called bonding electron pairs (PEI) and valence electron pairs that are not involved in the formation of covalent bonds are called free electron pairs (PEB). Covalent bonds generally occur between atoms of non-metallic elements, can be of the same type (for example: H2, N2, O2, Cl2, F2, Br2, I2) and different types (for example: H2O, CO2, etc.). Compounds that only contain covalent bonds are called covalent compounds.
Example of a Kovalen Bond
Covalent Chemical Compound Formula
By referring to the octet rule, we can predict the molecular formula of covalent-bound compounds. In this case, the number of electrons paired must be equalized. However, keep in mind that the octet rule is not always obeyed, there are some covalent compounds that violate the octet rule.
An example is the bond between H and O in H2O. Electron configuration H and O is H requires 1 electron and O requires 2 electrons. In order for O and H atoms to follow the octet rule, the number of H atoms given must be two, while O atoms are one, so the compound molecular formula is H2O.
bonding electron pairs
KOVALEN BOND TYPE
Based on the formation
A single covalent bond
A single covalent bond is a covalent bond that has 1 pair of PEI.
Example: H2, H2O (electron configuration H = 1; O = 2, 6).
Examples of bond formation in H2O molecules below:
A single covalent bond
A single covalent bond
Double covalent bond
A double covalent bond is a covalent bond that has 2 pairs of PEI.
Example: O2, CO2 (electron configuration O = 2, 6; C = 2, 4).
Here follows the formation of the 2-fold bonds in the CO2 molecule.
Double covalent bond
Double covalent bond
Triple covalent bond
A 3 covalent bond is a covalent bond that has 3 pairs of PEI.
Example: N2 (Electron configuration N = 2, 5).
The following is the formation of 3-fold bonds in the N2 molecule
Triple covalent bond
Based on Polarization:
Polar Covalent Bonds
Polar covalent bonds are covalent bonds in which the PEI tends to be attracted to one of the bonded atoms. The polarity of a covalent bond is determined by the electronegativity of an element. Polar covalent compounds usually occur between atoms of different elements with large electronegativity, having asymmetric molecular shapes, having dipole moments. Covalent bonds that occur between two different atoms are called polar covalent bonds. Polar covalent bonds can also occur between the same two atoms but have different electronegativity.
Examples of polar covalent bonds: HF
Examples of HF polar covalent bonds
In this HF compound, F has a high electronegativity compared to H ... so that the electron pair is more attracted towards F, as a result, dipoles are formed or polarity occurs (polar formation between H and F).
Nonpolar Covalent Bonds
Nonpolar covalent bonding is a covalent bond whose PEI is attracted equally to the bonding atoms. Nonpolar covalent compounds are formed between the atoms of elements that have zero electronegativity difference or have a dipole moment = 0 (zero) or have molecular symmetry. The negative charge points of the alliance electrons coincide, so that the molecules forming them do not occur dipole moments, in other words that the electron electrons get the same attraction.
Examples of Nonpolar H2 Covalent Bonds
Nonpolar covalent bonds consist of:
Kovalen Coordination Association
Coordination covalent bonds are covalent bonds in which the shared electron pair is donated by only one atom, while the other atom does not donate electrons. So here there is one atom giving a free electron pair, while another atom is the recipient. Co-ordinated covalent bonds are sometimes expressed by arrows (→) which show the direction of donation of electron pairs.