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Period

Noble Gas. Halogen. Alkali Earth Metal. Period. Alkali Metal. Group. p 237. Chemistry In Action. Natural abundance of elements in Earth’s crust. Natural abundance of elements in human body. CHEMICAL BONDS. CHAP 9. Homework for Chap 9 Read p 249 - 267 Applying the Concepts: 1 – 14,

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Period

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  1. Noble Gas Halogen Alkali Earth Metal Period Alkali Metal Group p 237

  2. Chemistry In Action Natural abundance of elements in Earth’s crust Natural abundance of elements in human body

  3. CHEMICAL BONDS CHAP 9

  4. Homework for Chap 9 Read p 249 - 267 Applying the Concepts: 1 – 14, 16 – 35, 36 – 44, 46 - 50

  5. Compounds and Chemical Change • Elements are composed of extremely small particles called atoms. • Compounds are composed of atoms of more than one element held together by chemical bonds. • 3. Molecule – smallest particle of a compound that can • exist and still retain characteristic chemical properties • Compounds occur as solids, liquids, and gases

  6. Fig. 9.2 Common gases exist as atoms or molecules

  7. Fig. 9.3 Example of a chemical reaction Burning magnesium (Mg) in air to produce magnesium oxide (“milk of magnesia”) Energy is released

  8. Fig. 9.4 (A) Photosynthesis stores solar energy Reactants Products Fig. 9.4 (B) Combustion releases solar energy

  9. Fig 8.20 Electron dot notation for representative elements 1 8 2 3 4 5 6 7 Valence electrons– outermost electrons in an atom Octet rule – atoms attempt to acquire 8 valence electrons

  10. Fig. 9.5

  11. Fig 8.21 energy + Na → Na+ + e− energy + Ca → energy + Al → Ca2++ e− Al3++ e− 1 8 2 3 4 5 6 7

  12. Three Types of Chemical Bonds • Ionic bonds • Electrons are transferred from one atom to another • Occur between a metal atom and a nonmetal atom • (2) Covalent bonds • Electrons are shared between two atoms • Occur between two nonmetal atoms • Metallic bonds • Metal atoms share many electrons in a “sea” that is free to move throughout the metal

  13. 11 protons 11 electrons 11 protons 10 electrons Na+ Na 17 protons 18 electrons 17 protons 17 electrons Cl- Cl Formation of an ionic bond + e− Net reaction: Na + Cl → Na+Cl− + energy This energy is called the heat of formation

  14. Fig. 9.6 Model of the sodium chloride crystal No molecules in an ionic compound! Formula unit + − Na+ ions Cl− ions

  15. Fig. 9.7 The cubic crystal structure of sodium chloride

  16. Ionic compounds consist of a combination of positive ions and negative ions • Ions are formed as nonmetal atoms gain and metal atoms lose electrons to achieve stable noble gas structure • The sum of the charges on the positive ions and negative ions in each formula unit must equal zero • How do we determine the formula for an ionic compound?

  17. 2 x +3 = +6 1 x +2 = +2 3 x -2 = -6 2 x -1 = -2 Formula of Ionic Compounds Al2O3 Al and O Al3+ O2- Ca and Br CaBr2 Ca2+ Br-

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