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Chapter 5 Chemical Bonds

Chapter 5 Chemical Bonds

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Chapter 5 Chemical Bonds

  1. 1. Chapter 5 Chemical Bonds
  2. 2. Formation of Chemical Bonds • Types of chemical bonds: 1. Ionic bond: formed when atom joined together by transferring of electrons between metal and non-metal atom 2. Covalent bond: formed when atom joined together by sharing electron between non- metal and non-metal atom
  3. 3. Ionic Bonds • Formed when atom joined together by transferring of electrons between metal and non-metal atom Metal atom Non-metal atom e donate electron receive electron Achieve the stable electron arrangement
  4. 4. Formation of ions Neutral atom Cation (+) Anion (-) Donate electrons Accepts electrons
  5. 5. Aluminium, Al 2.8.3 Al Donate 3 electrons Al 3+ 2.8 Aluminium atom, Al Aluminium ion, Al 3+ Al → Al + 3e 3+ -
  6. 6. Oxygen, O 2.6 O Accepts 2 electrons O 2- 2.8 Oxygen atom, O Oxide ion, O 2- O + 2e → O 2--
  7. 7. Formation of ionic bonds • Ionic compounds Compounds that are formed through ionic bonds Lets investigate the formation of sodium chloride, NaCl
  8. 8. 2.8.1 Na Cl+ 2.8.7 2.8 2.8.8 Cl - Na +
  9. 9. Explain the formation of sodium chloride + - -+ + - 1. Sodium atom, Na with the electron arrangement 2.8.1 2. Chlorine atom, Cl with the electron arrangement 2.8.7 3. Sodium atom, Na will donate 1 electron to achieve the stable electron arrangement to form sodium ion, Na Na → Na + e 4. Chlorine atom, Cl will receive 1 electron to achieve the stable electron arrangement to form chloride ion, Cl Cl + e → Cl 5. One sodium ion, Na and one chloride ion, Cl attracted by strong electrostatic force to form sodium chloride, NaCl
  10. 10. F + e → F 5. One magnesium ion, Mg and two fluoride ion, F attracted by strong electrostatic force to form magnesium fluoride, MgF 4. Fluorine atom, F will receive 1 electron to achieve the stable electron arrangement to form fluoride ion, F Mg → Mg + 2e 3. Magnesium atom, Mg will donate 2 electron to achieve the stable electron arrangement to form magnesium ion, Mg Explain the formation of magnesium fluoride 2+ - -2+ 2+ - 1. Magnesium atom, Mg with the electron arrangement 2.8.2 2. Fluorine atom, F with the electron arrangement 2.7 2
  11. 11. 2.8.2 Mg F + 2.7 2.7 F
  12. 12. 2.8 2.8 F - Mg 2+ 2.8 F -
  13. 13. Exercise • Explain the formation of ionic bond of: 1. Lithium fluoride 2. Sodium oxide 3. Magnesium oxide 4. Boron oxide 5. Aluminium oxide
  14. 14. Covalent Bonds • Formed when atom joined together by sharing electron between non-metal and non-metal atom • Types of covalent bonds: 1. single covalent bonds 2. double covalent bonds 3. triple covalent bonds
  15. 15. Single covalent bonds • A covalent bond formed when a pair of electrons is shared between two atoms Lets investigate the formation of hydrogen molecule
  16. 16. H 1 H+ 1 H H 2 2
  17. 17. 5. A single covalent compound with formula H is formed 4. Two hydrogen atom share pairs of electron to achieve the stable electron arrangement 3. Hydrogen atom, H contribute one electron each for sharing Explain the formation of hydrogen molecule - 1. Hydrogen atom, H with the electron arrangement 1 2. Hydrogen atom, H has one valence electron 2
  18. 18. Double covalent bonds • A covalent bond formed when a 2 pair of electrons is shared between two atoms Lets investigate the formation of oxygen molecule
  19. 19. 2.6 + 2.6 2.8 2.8 O O O O
  20. 20. 5. A double covalent compound with formula O is formed 4. Two oxygen atom share 2 pairs of electron to achieve the stable electron arrangement 3. Oxygen atom, O will contribute 2 electron each for sharing Explain the formation of oxygen molecule - 1. Oxygen atom, O with the electron arrangement 2.6 2. Oxygen atom, O has 6 valence electron 2
  21. 21. Triple covalent bonds • A covalent bond formed when a 3 pair of electrons is shared between two atoms Lets investigate the formation of nitrogen molecule
  22. 22. 2.5 + 2.5 2.8 2.8 N N N N
  23. 23. 5. A triple covalent compound with formula N is formed 4. Two nitrogen atom share 3 pairs of electron to achieve the stable electron arrangement 3. Nitrogen atom, N will contribute 3 electron each for sharing Explain the formation of nitrogen molecule - 1. Nitrogen atom, N with the electron arrangement 2.5 2. Nitrogen atom, N has 5 valence electron 2
  24. 24. 7. A covalent compound with formula H O is formed 6. Two hidrogen atom share 1 pairs of electron with 1 oxygen atom to achieve the stable electron arrangement 5. Oxygen atom, O contribute 2 electron for sharing Explain the formation of water molecule 1. Hydrogen atom, H with the electron arrangement 1 4. Hidrogen atom, H contribute 1 electron for sharing 2 2. Oxygen atom, O with the electron arrangement 2.6 3. The valence electron of hydrogen atom, H is 1 and oxygen atom, O is 6
  25. 25. OH H
  26. 26. Explain the formation of: - 1. Carbon dioxide molecule 42. Methane, CH
  27. 27. Properties of Ionic and Covalent Compounds Ionic Compound Exist as solid at room temperature High melting and boiling points Conduct electricity in aqueous solution or molten state Dissolve in water BUT do not dissolve in organic solvents Covalent Compound Exist as solid, liquids or gases Low melting and boiling points Do not conduct electricity at any state Dissolve in organic solvents BUT do not dissolve in water
  28. 28. Electrical conductivity • In solid state, ions do not move freely. Hence, ionic compound does not conduct electricity in solid state • In aqueous or molten state, ions are free to move. Hence, the compound can conduct electricity
  29. 29. Electrical conductivity • A covalent compound consist of neutral molecules • There are no free moving ions in covalent compound • Hence, covalent compounds do not conduct electricity at any state
  30. 30. Melting and boiling points • Ionic compounds are held together by strong electrostatic forces • More heat energy is needed to overcome the strong forces
  31. 31. Melting and boiling points • Covalent compounds are held together by weak intermolecular forces • Less heat energy is needed to overcome the weak forces

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