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Welcome back!. Definitions Ion an atom that has gained or lost one or more electrons Cation a positively charged ion Anion a negatively charged ion. Energy Level Diagram. e -. e -. e -. e -. e -. e -. 3p. e -. e -. 3 s. Energy. e -. e -. e -. e -. e -. e -. 2p. Sodium.

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  1. Welcome back!

  2. Definitions Ion an atom that has gained or lost one or more electrons Cation a positively charged ion Anion a negatively charged ion

  3. Energy Level Diagram e- e- e- e- e- e- 3p e- e- 3s Energy e- e- e- e- e- e- 2p Sodium Ion Na+ e- e- 2s It could GAIN seven electrons to become more stable. Or… e- e- 1s Or it could LOSE one electron to become more stable.

  4. All physical systems tends towards a configuration of lowest energy Sodium will LOSE an electron.

  5. Energy Level Diagram e- e- e- e- e- e- 3p e- e- 3s Energy e- e- e- e- e- e- 2p Chlorine e- e- 2s It could gain ONE electron to become more stable. Or… e- e- 1s Or it could lose SEVEN electrons to become more stable.

  6. Energy Level Diagram e- e- e- e- e- e- 3p e- e- 3s Energy e- e- e- e- e- e- 2p e- e- Chlorine Ion Cl- 2s e- e- 1s Gaining an electron would require the least amount of energy!

  7. Valence electrons Electrons in the outermost s and porbitals These are the most reactive

  8. Energy Level Diagram 3p e- 3s Energy e- e- e- e- e- e- 2p e- e- Sodium 2s Has only ONE electron in its outermost s and p orbitals. Therefore, it has one valence electron. e- e- 1s

  9. Energy Level Diagram e- e- e- e- e- 3p e- e- 3s Energy e- e- e- e- e- e- 2p e- e- Chlorine 2s Has SEVEN electrons in its outermost s and p orbitals. Therefore, it has seven valence electrons. e- e- 1s

  10. An easier way to draw the valence electrons is through… Lewis dot structures

  11. Sometimes atoms get together and one or more electrons jumps from one atom to another… …this causes both atoms to have opposite charges (ions)… …which then causes these ions to be attracted to each other. Ionic Bond

  12. For example… Chlorine has a greater attraction for electrons than Sodium But why? Electronegativity / Chlorine = catcher

  13. Ionic bonds Occur between metals and nonmetals Like Sodium and Chlorine or Potassium and Fluorine

  14. K F In an ionic bond, electrons are first lost or gained, resulting in the formation of ions.

  15. K F

  16. K F

  17. K F

  18. K F

  19. K F

  20. An ionic bondforms from the attraction between the positive K+ ion and the negative F- ion _ K + F Potassium (K+) ion [cation] Fluoride (F-) ion [anion]

  21. An ionic bondforms from the attraction between the positive K+ ion and the negative F- ion _ K + F The compoundpotassium fluoride (KF) consists of potassium (K+) ions and fluoride (F-) ions

  22. Ionic Bonds Properties of Ionic Compounds Electrons are exchanged Ions are formed Ions “stick together” magnetically to form compound Formed between metals and nonmetals Electronegativity difference >1.7 Cation + Anion = “salt” Forms crystals (ordered arrangements of ions) Conduct electricity when dissolved or melted High melting/boiling points Hard and brittle Rarely burn Formation is always exothermic

  23. Covalent Bonds Properties of Covalent Compounds Electrons are shared No ions are formed Formed between two nonmetals Electronegativity difference is minimal Low melting and boiling points Typically soft and squishy Usually do not dissolve in water as well as ionic compounds Don’t conduct electricity Sometimes burn

  24. Covalent bonds Occur between two nonmetals Like Hydrogen and Chlorine or Chlorine and Chlorine

  25. In covalent bonding, atoms still want to achieve the lowest energy level possible (which means filling up all eight of their valence seats.) But rather than losing or gaining electrons, atoms now SHARE an electron pair.

  26. Covalent bonds attempt to fill up all eight of their valence seats… Just like noble gases! All physical systems tends towards a configuration of lowest energy

  27. Chlorine forms a covalent bond with itself Cl2

  28. How will two chlorine atoms react? Cl Cl Each chlorine atom wants to gain one electron to fill all of its seats.

  29. Cl Cl

  30. Cl Cl

  31. Cl Cl

  32. Cl Cl

  33. Cl Cl The octet is achieved by each atom sharing the electron pair in the middle.

  34. Cl Cl Full 8 seats (octet) Full 8 seats (octet)

  35. Cl Cl The octet is achieved by each atom sharing the electron pair in the middle.

  36. Cl Cl This is the bonding pair It is a single bonding pair It is called a SINGLE BOND Single bonds are abbreviated with a dash

  37. Cl Cl This is the bonding pair It is a single bonding pair It is called a SINGLE BOND Single bonds are abbreviated with a dash

  38. Cl Cl circle the electrons for each atom that completes their octets Single bonds are abbreviated with a dash

  39. Cl Cl This is the chlorine molecule Cl2 circle the electrons for each atom that completes their octets

  40. Covalent bonds You know this… But you need to learn this! …and this. Remember: Covalent bonds occur between two nonmetals!

  41. O2 Oxygen can also form a covalent bond with itself. But it needs to form two bonds since it is in Group 6A. How can this be done?

  42. O O

  43. O O Each atom has two unpaired electrons

  44. O O

  45. O O

  46. O O

  47. O O

  48. O O Both electron pairs are shared.

  49. O O 6 valence electrons plus 2 shared electrons = full octet

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