Ions

Ions

1. Under some circumstances, the atoms of most elements will either gain or lose one or more of their outermost electrons. The process of gaining or losing electrons is called Ionization, and it results in the formation of an Ion. An Ion is an electrically charged atom or groups of atoms. Ionization results in metals and non-metals forming compounds. Most ion formation takes place when metals and non-metals form ionic compounds. Metal atoms tend to form cations by losing electrons to non-metals, which form anions. You may wondering why metals tend to lose electrons, while non-metals tend to gain them. Atoms gain or lose electrons so that they have the same number of electrons as the nearest noble gas. This makes them more stable. In chemistry, becoming more stable means becoming less reactive.

   • Cations
     • Positively charged ions are called Cations. Most cations form when metal atoms lose electrons. When a cation is forming, the lost electrons usually move to another atom. Electrons are negatively charged. When they leave an atom, the ion that remains is positively charged because it now has more protons than electrons. Metal atoms tend to form cations by losing electrons to non-metals
       • For example, the periodic table shows that a sodium atom has 11 protons. Therefore, it also has 11 electrons. A sodium ion forms when the sodium atom loses one electron. This means that the positive charge in the sodium becomes one greater than the negative charge. So the sodium ion has a positive charge. An ions charge is sometimes shown as a subscript after the atomic symbol. In this example, the sodium ion would be written as Na . The magnesium ion has a charge of 2 , so it is written as Mg .
   • Anions
     • Negatively charged ions called Anions. Most anions form when non-metal atoms gain electrons. Metal atoms tend to form cations by losing electrons to non-metals, which form anions.
       • For example, oxygen atoms can gain two electrons. The periodic table shows that an oxygen atom has 8 protons,and therefore, it has 8 electrons. By gaining two electrons, the oxygen atom becomes a negatively charged ion, called an Oxide Ion. It can be written as O . Note that the name of an elements anion is written by using the first part of the elements name and changing the last part to "-ide." So the nitrogen anion N , for example, is called nitride. The fluorine atom in forms a fluoride ion, F .

2. For example, a sodium ion is less reactive than a sodium ion. Sodium metal contains only atoms. When it is placed in water, a vigorous reaction occurs. Table salt contains sodium ions (and chloride ions). When it is placed in water, it dissolves quietly.