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 chlorideNaCl

Magnesium oxideMgO

Try magnesium + fluorine

1. Determine how many electron(s) magnesium need to lose, therefore the charge of the magnesium ion

2. Determine how many electron(s) fluorine need to gain, therefore the charge of the fluoride ion

3. 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

1. Determine how many electron(s) sodium need to lose, therefore the charge of the sodium ion

2. Determine how many electron(s) oxygen need to gain, therefore the charge of the oxide ion

3. Determine how many of each ions are needed to balance out the positive and negative charges

2 Na+ + O2- Na2OSodium oxide

Naming simple ionic compounds

1. Write the name of the metal. 2. Write the name of the nonmetal with the ending

changed to –ide.Example: Chlorine = chloride Oxygen = oxideFluorine = fluoride Sulfur = sulfideIodine = iodide Nitrogen = nitrideBromine = 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

1. Memorize the first 20 elements (This week)– Atomic number– Name– Atomic symbol

2. Memorize the common polyatomic ions (Next week)– Name– Formula– Charge

Magnesium + nitrogen1. Magnesium has 2 valence electrons2. Magnesium needs to lose 2 electrons to meet the octet rule3. Forms Mg2+ cation

Mg Mg2+ + 2e-

4. Nitrogen has 5 valence electrons5. Nitrogen needs to gain 3 more electrons to meet the octet rule6. Forms N3- anion (nitride ion)

N + 3e- N3-

Lowest common multiple of 2 and 3 = 63 Mg 3 Mg2+ + 6e-2 N + 6e- 2 N3-

Magnesium nitride Mg3N2