Ionic Compounds
Definition and meaning of Ionic Compounds in chemistry.
Ionic compounds are substances composed of positively charged cations and negatively charged anions held together by strong electrostatic attractions, arranged in a repeating three-dimensional crystal lattice.
In more detail
They typically form when a metal atom transfers one or more electrons to a nonmetal atom, producing a stable cation and anion pair (though ammonium and other polyatomic ions can substitute for a simple metal cation). In the solid state, ions are locked in fixed lattice positions, so ionic compounds are hard, brittle, and have high melting and boiling points because breaking the lattice requires overcoming many strong ionic bonds at once. Solid ionic compounds do not conduct electricity, but once melted or dissolved in water, the ions become free to move and the resulting liquid or solution conducts current.
Key facts
| Field | General Chemistry |
|---|---|
| Common Example Formula | NaCl (sodium chloride) |
| Bond Type | Ionic (electrostatic attraction) |
| Typical Formation | Metal + nonmetal, via electron transfer |
Sodium chloride (NaCl) forms when a sodium atom transfers its single valence electron to a chlorine atom, giving Na+ and Cl- ions that pack into a cubic lattice, the familiar crystal structure of table salt.
Frequently asked questions
Why do ionic compounds have such high melting points?
Because their ions are held in a rigid lattice by strong electrostatic attractions in all directions, and melting requires supplying enough energy to overcome many of these bonds simultaneously.
Can ionic compounds conduct electricity?
Not as solids, since the ions are fixed in place, but once molten or dissolved in water the ions can move freely, allowing the liquid or solution to conduct electric current.