1. 6.2 Covalent Compounds (Pages 232-240)

2. Learning Goals I can explain how covalent compounds are formed. I can describe the properties of covalent compounds. I can write formulas for covalent compounds when given the names of the compounds. I can write the names of covalent compounds when given the formulas.

3. Covalent Compounds Most simple covalent bonds are composed of linked or bonded atoms of different elements. These elements are usually two or more non-metals The attraction between molecules is much weaker than the attraction between oppositely charged ions in an ionic crystal. This contributes to the differences in the properties of ionic compounds and some covalent compounds.

4. Characteristics of Covalent Compounds Many covalent compounds tend to have low melting points and low solubility in water, compared with ionic compounds. Many covalent compounds are also poor conductors of heat and electricity. Plastics are a large class of polymer covalent compounds. Their numerous uses include shopping bags, containers, and fabrics. There are, however, many environmental concerns associated with the use of plastics.

5. Watch this video on ionic and covalent bonds: http://ed.ted.com/lessons/how-atoms-bond-george-zaidan-and-charles-morton

6. Covalent Bonds: 1.Which type of elements are covalent compounds composed of? Only non-metals are combined to form covalent compounds. 2. What happens to electrons in a covalent bond? Electrons are shared between elements.

7. 3. Draw the Bohr-Rutherford models for water.

8. 4. What is a molecule? A molecule is the smallest discrete particle of a pure substance, which has one or more shared pairs of electrons. 5. What is the other term used for covalent compounds? Covalent compounds are also called molecular compounds.

9. 6. Prefixes for Covalent Compounds PrefixNumberPrefixNumber Mono1Hexa6 Di2Hepta7 Tri3Octa8 Tetra4Nona9 Penta5Deca10

10. 7. Explain how to name covalent compounds. The prefixes mono, di, tri, tetra, etc. are used to show the number of atoms in the compound. Examples: Dinitrogen monoxide – N 2 O Dinitrogen trioxide – N 2 O 3

11. 8. Write formulas for the following covalent compounds: a)Carbon tetrachloride b)Trinitrogen pentaoxide c)Carbon monoxide d)Heptasulfur dioxide e)Pentanitrogen trioxide

12. 9. Name each of the following compounds. a)SiCl 4 b)SCl 6 c)N 2 C d)C 3 F 5 e)CO 2

13. 10. List some properties of covalent compounds: Since the attraction between molecules in a covalent compound are weak they have relatively low melting & boiling points Relatively soft when copared to ionic compounds Poor conductors of electricity and heat

14. 11. What are plastics made of? Plastics are made of molecular compounds called polymers. One common type of plastic used to make bags, toys, bottles, and containers is called polyethylene. It is compound composed of the elements hydrogen and carbon.

15. 12. Why might a city consider imposing a charge or ban on plastic bags? They may pose a ban because: Plastic bags are not biodegradable (they cannot be broken down naturally by living organisms) The small, broken-down particles of the plastic bags contain toxic materials that can get into water & soil Animals can be harmed if they eat discarded plastic or if they become trapped in pieces of plastic.

16. 13. Brainstorm a list of solutions to reduce the use of plastic bags. Use a cloth bag/reusable bag Carry your purchases when possible Use a shopping cart/trolley

17. Practice Page 241 # 1-8