1. Ionic and Covalent bonds

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 Sodium Ion Na+ Energy e- e- e- e- e- e- 3p e- e-
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 Chlorine Energy e- e- e- e- e- e- 3p e- e- 3s e-
It could gain ONE electron to become more stable. Or… e- e- 1s
Or it could lose SEVEN electrons to become more stable.

6. Gaining an electron would require the least amount of energy!
Energy Level Diagram e- e- e- e- e- e- 3p e- e-
Energy 3s 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 p orbitals
These are the most reactive

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

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

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

12. 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

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

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

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

16. K F

17. K F

18. K F

19. K F

20. K F

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

22. K F _ + An ionic bond forms from the attraction
between the positive K+ ion
and the negative F- ion _ K + F
The compound potassium fluoride (KF)
consists of potassium (K+) ions
and fluoride (F-) ions

23. Properties of Ionic Compounds
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

24. Covalent bonds Occur between two nonmetals Like Hydrogen and Chlorine
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. All physical systems tends towards a configuration of lowest energy
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. Cl Cl How will two chlorine atoms react?
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. Single bonds are abbreviated with a dashCl 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. Single bonds are abbreviated with a dashCl 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. Single bonds are abbreviated with a dashCl Cl
circle the electrons for
each atom that completes
their octets
Single bonds are abbreviated with a dash

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

40. Covalent bonds But you need to learn this! …and this.
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

43. O
Each atom has two unpaired electrons

44. O

45. O O

46. O O

47. O O

48. Both electron pairs are shared.

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

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

51. O O
Two bonding pairs,
making a double bond.

52. O O =
For convenience, the double bond
can be shown as two dashes.

53. This is the oxygen molecule,=
This is the oxygen molecule, O2

54. Properties of Covalent Compounds
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

55. Covalent bonds Two kinds… Polar Covalent Bond
Shared electrons spend more time closer to one of the bonding atoms
For example – H20
Non-Polar Covalent Bond
Shared electrons do not spend more time closer to one of the bonding atoms
For example – 02

56. Polar covalent bonds
Shared electrons spend more time closer to one of the bonding atoms
The electrons spend more time near the oxygen atom. H H
Oxygen
The probability distribution for shared electrons.

57. How can you tell if you have a polar or non-polar covalent bond?
ELECTRONEGATIVITY
Electronegativity is the power of an atom to attract electrons
The higher the value, the more electronegative the element

58. Remember probability distribution?

59. Non-polar covalent bonds
Shared electrons do not spend more time closer to one of the bonding atoms
The probability distribution for shared electrons is shared by both.
Oxygen
Oxygen

60. Every element (except the nobles) have electronegativity

61. Non-polar covalent bond
If the electronegativity difference between the two nonmetals is less than 0.3
Polar covalent bond
If the electronegativity difference between the two nonmetals is

62. Review Ionic bond Between a metal and nonmetal
Electrons are lost/gained and the resulting change in charge attracts the ions together
Covalent bond
Between two nonmetals
Electrons are shared between the atoms
Polar/Non-polar
Ruled by electronegativity