Ions are electrically charged particles formed when atoms lose or gain electrons. They have the same electronic structures as noble gases. Metal atoms form positive ions, while non-metal atoms form negative ions. The strong electrostaticforces of attraction between oppositely charged ions are called ionic bonds.
Metal atoms lose the electron, or electrons, in their highest energy level and become positively charged ions. Non-metal atoms gain an electron, or electrons, from another atom to become negatively charged ions
The number of charges on an ion formed by a metal is equal to the group number of the metal; aluminium would be 3+, and magnesium would be 2+.
The number of charges on an ion formed by a non-metal is equal to the group number minus eight; nitrogen would be 3-, and flourine would be 1-.
Hydrogen forms H+ ions, despite it being a non metal.
Sodium is in group one, so it will lose the electron in it's highest energy level and become Na+.
A sodium ion has the same electronic structure as a neon atom (Ne): 2, 8. However, it is not the same as a neon atom, as they have different numbers of protons and neutrons in their respective nuclei (Neon has 10 protons and 10 neutrons, but sodium has 11 neutrons and 12 protons)
Fluorine is in Group 7. It has seven electrons in its highest energy level. It gains an electron from another atom in reactions, forming a fluoride ion, F-. The atom is called fluorine, but the ion is called fluoride. Once again, a fluoride ion is not a neon atom, because the nucleus of a fluoride ion is the nucleus of a fluorine atom
When metals react with non-metals, electrons are transferred from the metal atoms to the non-metal atoms, forming ions. The resulting compound is called an ionic compound.
The metal atoms give electrons to the non-metal atoms. The metal atoms become positive ions and the non-metal atoms become negative ions.
- sodium + chlorine → sodium chloride
- magnesium + oxygen → magnesium oxide
- calcium + chlorine → calcium chloride
There is a strong electrostatic force of attraction between these oppositely charged ions, called an ionic bond.
The elements in Group 1 of the Periodic Table are called the alkali metals. They form ionic compounds when they react with non-metals. Their ions have a single positive charge. For example, sodium forms sodium ions, Na+.
The elements in Group 7 of the Periodic Table are called the halogens. They form ionic compounds when they react with metals. Their ions have a single negative charge. For example, chlorine forms chloride ions, Cl–.
Sodium chloride, NaCl, forms when sodium and chlorine react together. It contains oppositely charged ions held together by strong electrostaticforces of attraction – the ionic bonds. The ions form a regular lattice in which the ionic bonds act in all directions.