What Is Bond

Atoms form molecules when two or more are bonded together.

Covalent bonds are formed when electrons in the outermost orbital are shared between two atoms. With this type of bond forming, molecules can rotate around their shared electrons and change shapes. Each atom forms a characteristic number of covalent bonds. The number of bonds depends on the number of electrons in the outer orbital.

For example:

• Hydrogen (H) has atomic number 1, with 1 electron in its outer orbit. Hydrogen forms 1 bond (single bond) meaning: 1 electron is shared.
• Oxygen (O) has atomic number 8, with 6 electrons in its outer orbit. Thus Oxygen forms 2 bonds (double bond) meaning: 2 electrons are shared.
• Nitrogen (N) has atomic number 7, with 5 electrons in its outer orbit. Nitrogen forms 3 bonds (triple bond) meaning: 3 electrons are shared.
• Carbon (C) has atomic number 6, with 4 electrons in its outer orbit. Carbon forms 4 bonds, meaning: 4 electrons are shared.

In general: # of electrons in outer orbit + Shared electrons = 8 (full octet)

Make note that any electron shared is in an attempt to reach a stable state. In most atoms, this is an octet, or eight electrons in the outer orbit. Note Hydrogen only has space for 2 electrons in its outer orbit, one present and one shared.

Ions are atoms with a net electric charge due to the gain or loss of one or more electrons. Ionic bonds are bonds formed between two oppositely charged ions. Cations are ions with a net positive charge, while anions are those with a net negative charge.

Ionic forms of elements are important to the body, as they are able to conduct electricity when dissolved in water. These ions are called electrolytes. Single atoms, or atoms that are covalently linked in molecules can undergo ionization. Where R is any molecule attached to the shown functional group.

An atom with a single electron in its outermost orbital is known as a free radical. Free radicals are highly reactive and short-lived. In organism terms, they are responsible for the cellular breakdown. Sun damage is a classic example of free radicals acting on skin cells.

Polar bonds are bonds in which the electrons are shared unequally. The unequal sharing gives the atom with the higher share a more negative charge and the one with the lower share of electrons has a slightly more positive charge.

Hydrogen bonds are weak bonds between the hydrogen atom (more positive, the lesser share of the electron) in one polar bond and an oxygen or nitrogen atom (more negative, greater share of the electron) in another polar bond.