Огляд ковалентних зв'язків

Covalent Bonding

What is it?

• It is the sharing of electrons between two or more atoms.
• Covalent bonds are chemical bonds formed between two nonmetals

How does it occur?

• When atoms get near each other, their nuclei attract each other's electrons. The attraction causes the two atoms to form a bond. When this happens, their electron densities shift towards each other. So, they share their electrons.

• Different atoms, depending on what they are, will form longer or shorter bond lengths as well as have a higher or lower bond energy.

Types of Covalent Bonds

There are two different types of covalent bonds. The electronegativity difference between the elements determines how evenly the electrons are shared.

• In polar covalent bonds the electrons are unequally shared between the atoms.

• The unequal sharing creates a dipole. One side of the molecule has a partial positive charge. The other side has a partial negative charge.

• Polar molecules experience dipole-dipole interaction, ion-dipole interactions, and hydrogen bonding.

• In nonpolar covalent bonds the elections are equally shared between the atoms.

• The only intermolecular force they experience is London dispersion.

In order to reach the most stable state, atoms try to form full electron shells, meaning 8 valence electrons. But how do they do this? They can form ions by losing or gaining electrons, but a particle with an unbalanced charge is still fairly unstable.

Most of the time, atoms form full outer shells of electrons by sharing their electrons among multiple atoms, a process called covalent bonding. That way, each atom can have a full outer shell of electrons, but the overall entity of bonded atoms, called a molecule or compound, can have an equal number of protons and electrons, and therefore, a neutral charge.

The chemical compound depicted above is methane, ($CH_{4}$). It's made of one carbon, which has 4 outer shell electrons, sharing an electron each with 4 hydrogen atoms, which have 1 outer shell electron. Remember, hydrogen only needs two electrons to fill its 1s-orbital. Each bonding pair of electrons is a single bond. If two atoms were to share four electrons between them, they would have a double bond.

Other types of bonding include ionic bonds and metallic bonds.

(Video) GCSE Chemistry - Covalent Bonding #14

by Cognito

In this video, you will learn what covalent bonds are, how they form, and how to draw covalent compounds.