1. Bonding

2. Why do atoms bond? Atoms bond to get 8 valence electrons! Octet Rule: atoms need 8 valence electrons to be stable. 2 ways to get 8 1. transfer electrons (forms ions) 2. Share electrons Ionic bonding Covalent bonding

3. Ionic Bonds (Review) electrons -Atoms lose or gain electrons to become stable (like a noble gas)‏ -occurs between a metal and non- metal -occurs between a positive ion and negative ion

4. Covalent Bonds share electrons -Atoms share electrons to become stable (like a noble gas)‏ -occurs between 2 non-metals molecules -covalent compounds are called molecules

5. Which of the following are molecular and which are ionic? NaBrCO 2 O 3 NO KClAlBr 3 Ionic Molecular Ionic Molecular Ionic

6. Covalent Bonding

7. 2 Types of Covalent Bonds equally Nonpolar covalent- electrons are shared equally unequally Polar Covalent- electrons shared unequally

8. Naming and Writing Formulas of Covalent Compounds

9. Polar Bonds -have a partial negative charge on the more electronegative atom -have a partial positive charge on the less electronegative atom

10. Nomenclature Since electrons are shared two elements can bond in different ratios Ex.:COCarbon monoxide CO 2 We name covalent (molecular) compounds using prefixes to indicate the number of atoms of each. Carbon dioxide

11. Prefixes * Mono- is only used for the second element

12. Nomenclature: 1) Name the first element that appears in the formula. 2) Name the second element that appears in the formula, changing its ending to –ide. 1. N 2 O 4 * There are 2 nitrogen atoms and 4 oxygen atoms Name: dinitrogen tetraoxide 2. NO nitrogen monoxide Naming Molecular Compounds

13. Examples NO ₂ As ₂ O 5 PCl ₃ CCl ₄ Nitrogen dioxide Diarsenic pentoxide Phosphorous trichloride Carbon tetrachloride

14. Writing Formulas for Covalent Compounds -Prefixes tell you subscripts for elements! Ex.: 1. Nitrogen trioxide Nitrogen has no prefix so there is 1 atom of nitrogen The prefix tri- means there are 3 oxygens Formula: NO 3

15. Examples dihydrogen monoxide sulfur hexafluoride xenon trioxide tetraphosphorus trisulfide H2OH2O SF 6 XeO 3 P4S3P4S3