1. Chapter 8: Covalent Bonding The Nature of Covalent Bonding (Part 1)

2. The Octet Rule in Covalent Bonding In ionic bonding, electrons are transferred so that each ion reaches the noble gas configuration. In covalent bonds, electron sharing usually occurs so that atoms attain the electron configurations of noble gases.

3. The Octet Rule in Covalent Bonding Example:  Each hydrogen atom has one electron.  A pair of hydrogen atoms share these two electrons when they form a covalent bond in the hydrogen molecule.  Thus, each hydrogen atom attains the electron configuration of helium, a noble gas with two electrons.

4. Single Covalent Bonds The hydrogen atoms in a hydrogen molecule are held together mainly by the attraction of the shared electrons to the positive nuclei. Two atoms held together by sharing a pair of electrons are joined by a single covalent bond.

5. Single Covalent Bond Example: H· + H· → H:H Hydrogen Atom Hydrogen Molecule Shared pair of electrons

6. Single Covalent Bond An electron dot structure such as H:H represents the shared pair of electrons of the covalent bond by two dots. :F· + ·F: → :F:F: Flourine Atom Flourine Molecule..

7. Single Covalent Bond A structural formula represents the covalent bonds by dashes and shows the arrangement of covalently bonded atoms. :F· + ·F: → :F:F: or :F – F: Flourine Atom Flourine Molecule..

8. Single Covalent Bond A pair of valence electrons that are not shared between atoms is called an unshared pair. 2H· + :O· → :O:H or :O – H H H Hydrogen Atoms Oxygen Atom Water Molecule... –

9. Checkpoint What does a structural formula represent? What is the electron dot structure of a methane molecule? Complete Practice Problems 7 & 8 on page 220.

10. Double & Triple Covalent Bonds Atoms form double or triple covalent bonds if they can attain a noble gas structure by sharing two pairs or three pairs of electrons.

11. Double & Triple Covalent Bonds A bond that involves two shared pairs of electrons is a double covalent bond. A bond formed by sharing three pairs of electrons is a triple covalent bond. :O: + :O: → O::O or O=O.. Oxygen Atoms Oxygen Molecule

12. 8.2 Section Assessment Complete questions 13, 14, 15, 20, 21.