CHEMICAL BONDING Lewis Dot Structures Ionic an Covalent Bonding Formula Writing Naming Compounds Molecular Models CHEMICAL BONDING To play the movies and simulations included, view the presentation in Slide Show Mode.

Two types of chemical bonds Bond Comparison Ionic Bonds Covalent bonds

Covalent Bonds vs. ionic Bonds Atoms share electrons Bonds between nonmetals and non metals They are in MOLECULES Ionic Bonds Atoms transfer electrons Bonds between metals and nonmetals They are in IONIC COMPOUNDS Lewis dot Structures have which type of Bond?

The type of bond can usually be calculated by finding the difference in electronegativity of the two atoms that are going together.

Electronegativity Difference If the difference in electronegativities is between: Ionic Bond: > 2.0 Polar Covalent: 0.4 – 2.0 Non-Polar Covalent: < 0.4 _ Example: NaCl Na = 0.8, Cl = 3.0 Difference is 2.2, so this is an ionic bond! Look at the first slide to see which molecules may be polar

Ionic bonds and ionic compounds How they combine – Ionic compounds– Ions – Writing ionic formulas –

Let’s look at Ionic bonds Ionic bonding is the attraction between positive and negative ions. Two kinds of ions Cations - + ions. Anions - neg ions. Electrons are transferred from one atom to another. Draw dot structures for magnesium and oxygen

Ionic compounds have ionic bonds and… Electrically neutral. MgCl2 High melting points (very strong bonds!) Brittle. Dissolve in water and then conduct electricity. Molton ionic compounds are excellent conductors. - 2+ - Cl Mg Cl

Write out these ions-- Chloride Magnesium ion Fluoride Aluminium ion Positive ions state the name then “ion” Negative ions end in “–ide”. Chloride Magnesium ion Fluoride Aluminium ion Ions that are in the transition metals: Look for the little number above the symbol… that is the oxidation state. Zinc ion Silver ion Iron III ion Iron VI ion

Review how to write ionic formulas Magnesium phosphide Lithium bromide Aluminium oxide Iron II oxide Ionic Formulas: Write out ions and switcheroo away!

Match making Exercise! Circle Round Exercise

Ionic compounds with polyatomic ions (gold sheets) What are the charges of these ions? Write them out… Phosphate Sulfate Hydroxide Practice: Sodium phosphate Calcium oxalate Silicon chromate Zinc hydroxide Ionic compounds with polyatomic ions (gold sheets)

Covalent bonds and molecules Two ways to write molecular formulas – Three types of covalent bonds – Covalent prefixes – Writing covalent formulas –

Molecules are shown two ways Can be a combination of 2 or a million elements. Molecular Formula C6H12O6 not CH2O (empirical formula) Structural Formula H N H H

Three types of covalent bonds

Covalent prefixes to determine molecularformula Name these molecules: CO CO2 H2O CF4 SI2 N3O Number of Atoms Prefix 1 mono - 2 di - 3 tri – 4 tetra – 5 penta – 6 hexa – 7 hept– 8 oct– 9 non – 10 dec –

Double and even triple bonds are commonly observed for C, N, P, O, and S H2CO SO3 C2F4

Now You Try One! Draw Sulfur Dioxide, SO2 Use the force… (or bonds) to hold atoms together