Objectives Explain the differences between an atom and an ion. Describe how an ionic bond forms. Identify the properties of ionic compounds.
Vocabulary Words Ion Ionic bond Polyatomic ion Crystal
Quick Review When can electrons transfer? Valence electrons Stable element Reactive element Atoms either gain or lose electrons to become more stable.
Ion An ion is an atom or group of atoms that has become electrically charged. When an atom loses an electron (loses negativity) it becomes a positive ion. When an atom gains an electron (gains negativity) it becomes a negative ion.
Ionic Bond An ionic bond is the attraction between two oppositely charged ions (like opposite poles of the magnet). In this example, the sodium ion is balanced by a chloride ion. The formula NaCl shows a 1:1 ratio.
Polyatomic Ions Polyatomic Ions are ions made of more than one atom. It is a group of atoms that act as one.
Properties of Ionic Compounds The characteristic properties of ionic compounds include: crystal shape high melting points electrical conductivity