Ions and Ionic Compounds

Valence Electrons and Ions All atoms want to have a full outer orbital to be stable. This means that most atoms will need to have 8 (or 2) electrons in their outermost shell. We call this a stable octet An atom can lose or gain electrons to obtain a stable octet. Atoms that have gained or lost electrons are called ions.

Ions Atoms that lose electrons have a positive charge and are called cations. Atoms that gain electrons have a negative charge and are called anions The noble gases have full outer orbits and therefore do not gain/lose electrons.

# electrons in valence shell Gain/Loss of Electrons Group # electrons in valence shell Gain/Loss of Electrons Charge 1   2 3 5 6 7 8

# electrons in valence shell Gain/Loss of Electrons Group # electrons in valence shell Gain/Loss of Electrons Charge 1 1  Lose 1  +1 2   3 5 6 7 8

# electrons in valence shell Gain/Loss of Electrons Group # electrons in valence shell Gain/Loss of Electrons Charge 1 1  Lose 1  +1 2 2  Lose 2 +2 3   5 6 7 8

# electrons in valence shell Gain/Loss of Electrons Group # electrons in valence shell Gain/Loss of Electrons Charge 1 1  Lose 1  +1 2 2  Lose 2 +2 3  3 Lose 3 +3 5   6 7 8

# electrons in valence shell Gain/Loss of Electrons Group # electrons in valence shell Gain/Loss of Electrons Charge 1 1  Lose 1  +1 2 2  Lose 2 +2 3  3 Lose 3 +3 5  5 Gain 3 -3 6   7 8

# electrons in valence shell Gain/Loss of Electrons Group # electrons in valence shell Gain/Loss of Electrons Charge 1 1  Lose 1  +1 2 2  Lose 2 +2 3  3 Lose 3 +3 5  5 Gain 3 -3 6 6  Gain 2 -2 7   8

# electrons in valence shell Gain/Loss of Electrons Group # electrons in valence shell Gain/Loss of Electrons Charge 1 1  Lose 1  +1 2 2  Lose 2 +2 3  3 Lose 3 +3 5  5 Gain 3 -3 6 6  Gain 2 -2 7  7 Gain 1 -1 8  

# electrons in valence shell Gain/Loss of Electrons Group # electrons in valence shell Gain/Loss of Electrons Charge 1 1  Lose 1  +1 2 2  Lose 2 +2 3 Lose 3 +3 5 Gain 3 -3 6 6  Gain 2 -2 7 Gain 1 -1 8 None!

The Formation of Ions The Formation of Ions A Bohr-Rutherford diagram for a Sodium Atom Atoms are neutral because they contain the same number of positive and negative charges. A Bohr Ruther ford Diagram of a sodium ion Na1+ (sodium atom with one lost electron)

Ionic Compound METAL + CATION (positive ion) Loses an electron(s) Ex. Li → Li1+    NON-METAL ANION (positive ion) Gains an electron(s) Ex. F → F1-

Ionic Compounds Transfer of Electrons to become STABLE and give a STABLE OCTET (full outer shell) The transfer of electrons results in a POSTIVE atom and NEGATIVE atom and these oppposite charges ATTRACT The forces that keep the IONS together are called an IONIC BOND

Examples Try these Lithium Fluoride Beryllium Oxide Magnesium Fluoride Aluminum Chloride

Molecular Compounds NON-METAL + METAL NO ions Valence electrons (outer shell) are SHARED The attraction between atoms in a molecular compound are called COVALENT BONDS

Oxygen Gas Double Bond

Fluorine Gas Single Bond

Examples Try the following: H2 O2 H2O CO2 CH4 C6H12O6