Ionic bond

One electron lost

One electron gained

The formation of sodium chloride (NaCl) from sodium (Na) and chlorine (Cl)

Note that we don’t have to draw the inner shell electrons anymore! These diagrams are called Lewis structures, Lewis dot diagrams, or electron dot diagrams

Name of compound: Sodium chloride Chemical formula: NaCl

Ions: cation and anion Ions – charged particles Cation: Metal atoms lose electrons to form positively charged ions Anion: Non-metal atoms gain electrons to form negatively charged ions Cations (+) and anions (-) attract each other by electrostatic attraction to form ionic compound

Cations (+) and anions (-) attract each other by electrostatic attraction in all directions

The pattern grows until a giant lattice structure of ions is formed Pure ionic compounds exist as solid crystals

Two electrons lost

Two electrons gained

Name of compound: Magnesium oxiide Chemical formula: MgO

Sodium chloride NaCl Magnesium oxide MgO

Try magnesium + fluorine Determine how many electron(s) magnesium need to lose, therefore the charge of the magnesium ion Determine how many electron(s) fluorine need to gain, therefore the charge of the fluoride ion Determine how many of each ions are needed to balance out the positive and negative charges

Two electrons lost

One electron gained

To obtain full outer shells, a magnesium atom must lose 2 electrons, and a fluorine atom must gain 1 electron.

Each magnesium atom loses two electrons to form magnesium ion Mg2+ Each fluorine atom gains one electron to form fluoride ion F-

Each magnesium atom reacts with two fluorine atoms to form magnesium fluoride with the chemical formular MgF2.

Try sodium + oxygen Determine how many electron(s) sodium need to lose, therefore the charge of the sodium ion Determine how many electron(s) oxygen need to gain, therefore the charge of the oxide ion Determine how many of each ions are needed to balance out the positive and negative charges

2 Na+ + O2-  Na2O Sodium oxide

Naming simple ionic compounds Write the name of the metal. Write the name of the nonmetal with the ending changed to –ide. Example: Chlorine = chloride Oxygen = oxide Fluorine = fluoride Sulfur = sulfide Iodine = iodide Nitrogen = nitride Bromine = bromide Phosphorous = phosphide

Polyatomic ions Ions made of more than one atom bonded together They behave as one ion with one overall charge

Example: Calcium carbonate Calcium ion – Ca2+ Carbonate ion – CO32-

Calcium carbonate – CaCO3

Homework Memorize the first 20 elements (This week) Atomic number Name Atomic symbol Memorize the common polyatomic ions (Next week) Formula Charge

Magnesium + nitrogen Magnesium has 2 valence electrons Magnesium needs to lose 2 electrons to meet the octet rule Forms Mg2+ cation Mg  Mg2+ + 2e- Nitrogen has 5 valence electrons Nitrogen needs to gain 3 more electrons to meet the octet rule Forms N3- anion (nitride ion) N + 3e-  N3- Lowest common multiple of 2 and 3 = 6 3 Mg  3 Mg2+ + 6e- 2 N + 6e-  2 N3- Magnesium nitride Mg3N2