1. Chemical Bonds Physical Science

2. Valence Electrons Electrons found in the last shell, orbital or energy level Code :  1,2,3,4,5,6,7,8  “A” columns

3. Electron Dot Diagrams An electron dot diagram is a model of an atom in which each dot represents a valence electron. Stable configuration—eight valence electrons

4. Electron Dot Practice 1. He _2_VE 2. C _4_VE 3. Ca _2_VE 4. Na _1_VE 5. Cl _7_VE VE= valence electrons

5. Valence Numbers/Oxidation Numbers Number of electrons that the element will gain or lose to become stable. Code: +1,+2, +3, +/-4, -3, -2,-1,0 A columns only

6. IONS Charged Particles Anion—an ion with a negative charge Cation—an ion with a positive charge

7. Goal of ALL Elements To have 8 electrons or the last shell full. Which family is stable? Nobel Gases (Inert Gases)

8. Chemical Bonding Chemical Bond: –2 or more elements chemically combine to form a compound. –The force holding atoms or ions together

9. Types of Bonds IonicCovalentMetallic Electrons are gained or lost Electrons are shared Electrons are gained or lost Metal and nonmetal EX: Table salt Nonmetal and nonmetal EX: Water or sugar Metal and metal EX: Any alloys

10. Properties and Arrangements in Ionic Bonds Properties Ionization- process of elements losing electrons. (metals) 1A, 2A, 3A Electron Affinity – process of elements gaining electrons. (nonmetals) 5A, 6A, 7A Arrangement of Ions Ratio shows equal proportions Crystal shape

11. Properties of Covalent Bonds Share electrons H 2 – Smallest covalent bond known How do I write covalent bonds? H:H Electron Dot Configuration Dots represent the electrons shared in the bond

12. Diatomic Atoms “Super Seven” Di means two. Definition: Elements combine with itself Members of the “super seven”: Group 7A plus H, N, and O H 2 N 2 O 2 F 2 Cl 2 Br 2 I 2

13. Polyatomic Ions Poly means many. Definition: Compound acting as a single charged element. Examples: NH 4 Ammonium C 2 H 3 O 2 Acetate ClO 3 Chlorate OH Hydroxide NO 3 Nitrate CO 3 Carbonate SO 4 Sulfate PO 4 Phosphate

14. Element – Compounds - Formulas Element A particle that cannot be broken down into smaller particles CarbonSymbol Letters that represent an element CCompound Two or more elements that chemically combine Sodium chloride Formulas Letters that represent a compound NaCl

15. Bond Comparison Bonds Melting Point Valence Electrons Elements Involved Ionic High Melting Pt Gain or Lose Electrons Metals and Nonmetals Covalent Low Melting Pt Share Electrons Nonmetals and Nonmetals Metallic High Melting Pt Free Flowing Electrons Metals and Metals

16. Naming Compounds (Binary) Binary- 2 elements 1.First element is its name 2.Second element ends in –ide 3.Combine them together NaCl NaCl Sodium Chloride

17. Naming Compounds (Polyatomic) Polyatomic- more than two elements. 1. First element is its name 2. Name the polyatomic ion 3. Combine together KNO 3 KNO 3 Potassium Nitrate Potassium Nitrate

18. Key Thoughts for Naming Never change the ending of a polyatomic Change the ending of the single element only if it is the second element (-ide)

19. Practice in naming KClMgO KClO 3 KC 2 H 3 O 2 NH 4 NO 3 Potassium chloride Magnesium oxide Potassium chlorate Potassium acetate Ammonium nitrate

20. Valence Numbers Know the Code Valence Numbers are also known as Oxidation numbers How many electrons an element will gain or lose to be stable. Codes: 1A= +15A= –3 2A= +26A= –2 3A= +37A= –1 4A= +/- 48A= 0

21. Writing and Balancing Formulas Rules 1. Write the symbols 2. Write the Valence # above each element. 3. See if the valence number = 0. 4. If not then cross over and write the oxidation numbers as subscripts. Don’t worry about the negative sign. Practice Problems 1. Mg Cl 2. K PO 4 3. NH 4 SO 4 4. Sodium Oxide

22. Answers MgCl 2 K 3 PO 4 (NH 4 ) 2 SO 4 Na 2 O

23. Formula and Naming with Weird Compounds If using a transitional metal in naming, the charge of the metal is in parenthesis. Covalent Bonds need to use prefixes – –Ex: Carbon Dioxide = CO 2