2. Covalent Bonds

3. Why do atoms bond? Atoms want noble gas configuration (octet) For ionic bonds there is a transfer of electrons to get an octet of electrons For covalent bonds there is a sharing of electrons to get an octet

5. What is a covalent bond? Covalent bond - is the chemical bond that results from sharing of valence electrons – Occurs with elements close to each other on the periodic table – Ex: H 2 O – Between a nonmetal and a nonmetal – Molecule is two or more atoms bonded covalently

6. Question Time What do atoms want to achieve? What is the octet rule? What is the difference between a covalent and a ionic bond? What is a molecule?

7. Examples of Molecules F 2 H 2 O NH 3 (ammonia) CH 4 (methane) Notice there are no metals, only non-metals

8. Diatomic molecules Some atoms do not exist as a single atom Atoms that exist as two H 2, O 2, N 2, Cl 2, Br 2, I 2, F 2 HONClBrIF Magnificent 7-don’t forget H

9. 3 Types of Covalent Bonds Single Covalent Bond Double Covalent Bond Triple Covalent Bond

10. 3 Pencil Demo for Single, Double and Triple Covent bonds Make as many observations as you can i.e. facial expressions, body position, muscles used, noises made, force or energy exerted, etc.

11. Single Covalent Bonds Each atom shares one pair of electrons Each atom shares 2 electrons Longest bond Weakest bond of the three

12. Double Covalent Bonds In a double bond, each atom shares two pairs of electrons Each atom shares 4 electrons Medium length bond Medium strength bond

13. Triple Covalent Bond In a triple covalent bond, each atom shares three pairs of electrons Each atom shares 6 electrons The shortest bond The strongest bond Carbon, nitrogen, oxygen, and sulfur can form double and triple covalent bonds

14. Question Time What is a diatomic molecule? What are the diatomic molecules? What is a single covalent bond? Double covalent bond? Triple covalent bond? Which bond is the longest? Which bond is the strongest?

15. Covalent Molecule Properties Covalent molecular solids tend to be soft solids, liquids, or gases at room temperature Low melting and boiling points Poor conductors of heat and electricity Non-electrolytes – do not conduct electricity in water

16. Strength of Covalent Bond Several factors control bond strength —Number of shared electrons-the more electrons shared, greater the bond —Size of the atom —Bond length – the greater the bond length, the weaker the bond

17. Question Time What are the properties of covalent molecules? What factors control bond strength?