Matter Trends and Chemical Bonding

Expectations: B2.1, B2.4, B2.6, B2.7, B3.4, B3.5

2.1 Ionic Compounds

Learning Goals

• By the end of this class I will…– Identify ionic compounds– Break down the process of ionic bonding– Derive chemical symbols for ions– Derive ionic formulas

Last Class

• Identified periodic trends– Atomic radii– Ionization energy– Electron affinity

Ionic Compounds

• Recall: – A compound is a pure substance made up of 2 or

more elements.– An ion is an atom or a group of atoms that have

either a positive charge or a negative charge• An ionic compound is a compound that is

formed between cations and anions

Ionic Compounds

Properties• Hard and Brittle• High melting and boiling points• Conduct electricity when

dissolved in water– Solutions of ionic compounds in

water are called electrolytes

Ionic Bonding

• Ionic Compound = Metal + Non-metal• In ionic bonding, a non-metal atom removes

an electron from a metal atom.– Metal loses electrons to form a stable cation– Non-metal gains electrons to form a stable anion

• The oppositely charged ions are attracted to each other by electrostatic forces, which are the basis of the ionic bond.

Ionic Bonding

• The result is a compound that has a neutral charge – EXAMPLE: Na+ + Cl- = NaCl (neutral)

**The total positive charge must balance** the total negative charge

Ionic Formula

• Try together: – calcium and chlorine– lithium and nitrogen– magnesium and oxygen– magnesium and nitrogen

Drawing Chemical Symbols

Ions as Lewis Structures: 1. Draw square brackets around the ion2. indicate the charge outside the brackets,

ie: Na+ and S2-

[Na]+ [ S ]2-..

..::

Drawing ionic Compounds

Draw the Lewis symbols to show the formation of bonds between sodium and oxygen. Write the chemical formula for the compound produced.

Drawing ionic Compounds

1. Write a Lewis symbol for each atom

Drawing ionic Compounds

1. Write a Lewis symbol for each atom2. Decide on the ratio of ions required to

produce a neutral ionic compound

Drawing ionic Compounds

1. Write a Lewis symbol for each atom2. Decide on the ratio of ions required to

produce a neutral ionic compound3. Draw each ion as a Lewis symbol.

Drawing ionic Compounds

1. Write a Lewis symbol for each atom2. Decide on the ratio of ions required to

produce a neutral ionic compound3. Draw each ion as a Lewis symbol. 4. Write the chemical formula

Drawing Chemical Symbols

• Draw Lewis symbols to show the formation of bonds and write the chemical formula for the compounds– calcium and chlorine– magnesium and oxygen– magnesium and nitrogen

Exit Ticket

Please complete and hand in before you go!

Draw Lewis symbols to show the formation of bonds within calcium oxide. Write the chemical formula for the compound produced.

Homework

Page 60# 4, 7, 8