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Ions
- 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 .
- 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 .
- 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
- 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 .
- 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 .
- 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.
- Cations
- 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.
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