What is a chemical bond? How are ions formed?

Ionic, covalent, or metallic bonds are the three main ways that two atoms can join to form a chemical bond.

Protons are positive and electrons are negative, like the North and South ends of a magnet, and they attract each other; neutrons are like lumps of rock and are only there to make up space. Protons and neutrons are all that make up an atom, with electrons orbiting around the outside.

The goal of atom bonding is to gain or lose electrons in order to change the number of electrons in their outer shells (electrons are arranged in shells, from the inside out, like rings on a tree). Eight electrons can be found in each shell, except in transition metals and the lanthanides and actinides, which act strangely and have more than eight electrons.) The innermost shell is the smallest and can have two electrons.

"Covalent" literally means "with valence," because all of the atoms' outer shells are together in covalent bonding, which is the sharing of electrons in the orbits of both atoms, completing their outer or valence shells.

Because the extra electrons in metals, such as iron, form a sea of negative electrons, the positive nuclei (protons and neutrons) are drawn to the negative sea. This process is known as metallic bonding. Because the electrons are relatively free—they don't belong to any specific atom—they can move around and conduct heat and electricity.

Ions are created when an atom actually donates or gives away electrons to other atoms. For example, if sodium gives one of its outer shell's seven electrons to chlorine, which already has seven, then chlorine has a full valence shell and sodium has an empty one. However, since the empty valence shell is empty, it can no longer exist, and you can therefore consider the next shell down to be the new outer shell, which is full.

Ionic bonding only occurs between non-metals and metals; the metals give electrons, the non-metals receive, so metals form positive ions, and non-metals negative. Now that sodium and chlorine ions have lost an electron and gained one, respectively, and since electrons are negative, sodium has become more positive and chlorine more negative. Similarly, North and South on a magnet now attract each other.

A chemical bond is a force of attraction between atoms that holds them together in a molecule. Ions are formed when atoms gain or lose electrons, resulting in a net electric charge. An atom becomes a positively charged ion (cation) when it loses electrons, and it becomes a negatively charged ion (anion) when it gains electrons.