Warm-Up #32 A. 34 Copy and Answer

1. How many valence electrons does calcium have?

2. If calcium lost two electrons, what would be its charge?

3. How many valence electrons does sulfur have?

4. If sulfur gained two electrons, what charge would it have?

5. How could you represent the valence electrons on an atom with just using the chemical symbol?

Ionic Bonding

Ionic Bonds

• What are ionic bonds?–An ionic bond forms when valence

electrons are transferred from one atom to another atom.

Ionic bonds are all around us.

Salt – Sodium Chloride Snail’s Shell – Calcium Carbonate

How are ionic bonds formed?

• In an ionic bond, one atom has lost electrons and the other atom has gained electrons.

• These atoms are called ions.• An atom that loses electrons becomes

positively charged (cation)• An atom that gains electrons becomes

negatively charge (anion)

Another Viewpoint

+

Can more than one electron transfer?

• YES!!!!

• Elements in Group 2 will donate 2 electrons and be given a +2 charge.– Magnesium will react with Oxygen to form

Magnesium Oxide (MgO)

A Few Rules for Ionic Bonds

• Ionic bonds form between a metal and a nonmetal.

• Metals lose the electrons becoming the cation.

• Nonmetals gain electrons and become the anion.

• The resulting ionic compound is electrically neutral because the charges between the atoms cancel.

Ionic Compounds

• Ionic compounds are made up of ions that are bonded in a repeating three-dimensional pattern called a crystal lattice.

Two Dimensional View

3-D View

Properties of Ionic Compounds

• Brittle solids at room temperature

• High melting points– MgO has a melting point of 2800 degree C

• Very high boiling points

• High solubility in water (dissolve easily in water)

Vocabulary Review

• Ion: a charged particle that forms when atoms gain or lose electrons

• Ionic bond: the attractive force between oppositely charged ions, which form when electrons are transferred from one atom to another

• Cation: positively charged ion• Anion: negatively charged ion• Crystal lattice: the regular pattern in which a

crystal is arranged