Today we discuss the difference between the two bonds.
A covalent bond is a type of bonding which occurs between two atomic nuclei.
This is where the electron structure of the atoms becomes shared between each nuclei in either a single, double or triple bond to give an overall more stable structure in the current environment that the atoms exist within.
A single covalent bond is where the spherical S orbitals of a pair of atoms combine to form what is known as a sigma bond.
To form a double bond, the P orbitals must be utilised.
What are P orbitals?
P orbitals are dumbbell-shaped orbitals that position in 90-degree angles from one another.
Due to the shortest distance between two atoms already being occupied by a sigma bond, the two atoms P orbitals would then align outside this axis forming a second bond.
A triple bond is where a second set of P orbitals at a 90-degree rotation to the double bond form.
Where does covalent bonding occur?
Usually in covalent bonding an electron for a bond would be supplied from both of the atoms to form a total of two electrons.
In some cases, both electrons can be supplied from a lone pair of electrons of a single atom which conjugate towards a positively-charged nucleus.
In aqueous solutions, however, it is a commonplace for ions to exist which, when positively charged, become very dense with charge (size vs. charge ratio).
This high charge density allows what is known as lone pairs of electrons to become attracted to the positive charge of the ion.
This is similar to a pair of magnets, due to electrons having a negative charge and the ion having a positive charge or vice versa.
What is a dative covalent bond?
When a collision occurs between the two charges, if the special alignment is correct and there is sufficient energy in the collision, the two electrons in the lone pair can form a type of covalent bond with the ions nucleus, where both electrons were supplied from a single molecule.
This type of bond is what is known as a dative covalent bond.
The effects of these dative covalent bonds upon a metallic ion, such as the ones measured in photometry, can have some interesting effects upon the overall electronic structure of the metal ion.
This can affect the way in which it undergoes excitation and, therefore, how it interacts with a flame photometer.