3rd entry(chem) : What are ions?

What are ions?
An ion is an electrically charged particle obtained from an atom or chemically bonded group of atoms by adding or removing electrons. Now what this means is that an ion is the result of taking away, or adding, electrons to an atom or a chemically bonded group of atoms. By taking away, or adding, these electrons, the particle takes on an electrical charge. Atoms are electrically neutral as they contain an equal number of positive and negative charges. An atom that adds an extra electron to it becomes a negatively charged ion. This type of ion is called an anion. An atom which loses one or more of its electrons now has a positive charge, and is called a cation.

For example, a sodium atom can lose one of its electrons and form a sodium cation. Now, instead of being Na, it would be Na+1. This means that the sodium atom has an overall positive charge of +1. Another example would be a neutral atom of Sulfur, S. If this atom of S were to gain two electrons it would become S-2. The sulfur atom would now have a total negative charge of -2.

How many protons and electrons does an ion have?

An ion has 16 protons and 18 electrons.

References:
http://www.cartage.org.lb/en/themes/sciences/chemistry/Generalchemistry/Matter/Atoms/AtomsIons/AtonsIons.htm
http://www.chem4kids.com/files/atom_ions.html