Chemical bonding happens when atoms from two or more different elements combine to form a new substance. An atom is made of three different subatomic particles. Inside the nucleus, there are protons that have a positive charge and neutrons that have no charge. Circling the nucleus are electrons containing a negative charge. These electrons combine causing the elements to chemically bond.

The ability of two elements to form a chemical bond is based on valence electrons, or the electrons in the outermost shell. An atom looks much like a miniature version of a solar system, the atoms orbit around the nucleus much like a planet around the sun. Each orbit, or shell, can only hold a specific number of electrons. The first can only hold two, the second eight, the third eighteen and so forth. When an atom has it’s last shell filled, it is very stable and does not usually combine with another atom of a different element to go through a chemical bonding process. When that shell is empty, the atom isn’t as stable and attracts atoms of other elements to fill its shell and become stable.

Chemical bonding can be classified in one of three ways. There are ionic bonds, covalent bonds, and metallic bonds. In each type of bond, the valence electrons act differently.

In ionic bonds atoms simply transfer one atom to another forming an ion. Atoms normally have a neutral charge. When chemical bonding occurs, there is an exchange of electrons and an ion, either a positively or negatively charged atom, is formed. The atom that gains an electron has a negative charge and is now a negative ion. The one that looses an electron becomes positively charged and becomes a positive ion. Much like a magnet with opposing poles, these atoms will now attract each other forming a chemical bond. An example of an ionic bond is sodium fluoride. Sodium has one valence electron and fluorine has seven. During the chemical bonding process, sodium will lose its one valance electron to fluorine, causing the sodium to become negatively charged and fluorine to become positively charge. They will then attract together and form sodium fluoride.

Covalent bonds form when there is a sharing of electrons. In this type of chemical bond, the atoms involved don’t easily lose electrons but look to fill up their outermost shell. Here, elements will share the same atoms; that is, the same atoms will occupy both elements at the same time. This often happens with elements that are similar to eachother. Hydrogen, for example, only has one electron and will attract another hydrogen atom to share electrons to fill up its shell.

When several like atoms combine, a molecule is formed. The elements in this type of chemical bonding process are called diatomic elements. These diatomic elements can also form covalent bonds with other diatomic elements. An example of a covalent bond where two diatomic elements share electrons is hydrochloride or hydrochloric acid.

The last type of chemical bond are metallic bonds. Metals such as copper, silver, gold and iron, tend to give up electrons easily. The nucleus of each atom attracts those free electrons, bonding them together in a metallic bond. The valence electrons form a common electron cloud which is attracted to the nucleus of each present atom. This results in the formation of a metal and the ability of these electrons to freely flow between atoms allows for the conduction of electricity and heat.