1.
Bonding

2. Chemical Bonding Bonding: Force that holds atoms together
Bonding is determined by electronic configuraton:
How many valence electrons?
Mg 12e- 1s2 2s2 2p6 3s2
Cl 17e- 1s2 2s2 2p6 3s2 3p5

3. Octet Rule Atoms To get a full shell of 8 valence electrons
Gain, Lose (transfer)
Or Share electrons
To get a full shell of 8 valence electrons
(except H and He are full at 2)
Forms neutral compounds: both ionic & covalent

4. Don’t confuse valence electron # with the charge on the ion
Ex: Oxygen
Valence electrons:
_6_
How many more to fill octet
__2_
So charge:
_-2_

5. Ionic Bonds: transfer electrons
Bond forms between Metal and Nonmetal
+ ion ion
Transfer electrons: creates ions
Metals lose electrons: form + ion (cation)
Nonmetals gain electrons: form – ion (anion)
Opposite charges attract to create bond
Like magnets

6. Properties of Ionic Bonding
Ionic bonds are one of the strongest types of bonding.
Ionic bonds are very strong, so ionic compounds are usually hard, brittle, with very high melting points and boiling points.
Solids at room temp

7. Properties of Ionic Bonding
Ions are packed into repeating patterns resulting in a crystal lattice structure.

8. Properties of Ionic Bonding
No single particle of an ionic compound → represented by the simplest ratio of ions, called a formula unit.

9. Properties of Ionic Bonding
Ionic compounds dissolve well in water and split up into their ions called dissociation.

10. Properties of Ionic Bonding
Electrolytes: ions conduct an electric current when dissolved in water.

11. Properties of Ionic Bonding
Good conductors of electricity as a liquid or when dissolved in water

12. Forming Ionic Compounds
Metals (+) are always written first
Compounds are neutral, so…
Ions must come together in the ratio to balance (+) with (-)

13. Lewis Dot Diagrams for Ionic compounds
Superscript = charge
H O2-
Subscript = # of atoms (do not write subscripts of 1)
H2O = 2 hydrogen atoms and 1 oxygen atom
H2O2 = 2 hydrogen atoms & 2 oxygen atoms

14. If lithium and fluorine bond, Li+ and F- would make LiF, because the positive 1 charge balances a negative 1 charge.
Li F Li1+ F1-

15. If lithium (Li+) and oxygen (O-2) bond, more positive lithiums are needed to balance out the larger negative of oxygen. It would take 2 lithiums for every 1 oxygen. To show two lithiums are needed, a subscript of “2” is written after the lithium, Li2O
Li O Li1+ O2- Li1+ Li

16. If an ionic compound is made from Aluminum (Al+3) and Sulfur (S-2), the amounts of each element needed would be:
Al+3 S-2
S-2
Totals: and -6
So the resulting compound would be Al2S3

17. Al S S S-2 Al+3 S-2 Al+3 S-2

18. Al S S S-2 Al+3 S-2 Al+3 S-2

19. Writing Ionic formulas
Write
Symbol
Charge as superscript
“Criss-cross” – to make subscripts
Reduce if you can

20. Writing Ionic formulas
Write
Symbol
Charge as superscript
“Criss-cross” – to make subscripts
Reduce if you can
Mg O-2
Mg2 O2
Mg2O2
Mg O

21. Try Calcium oxide, Potassium nitride, Magnesium phosphide, Ca2O2 CaO
K3N
Magnesium phosphide,
Mg3P2

22. Polyatomic Ions Ions with 2 or more atoms Acts as a single unit
Use parenthesis if subscript is more than 1
Sulfate: SO4-2
Aluminum sulfate:
Al+3 SO = Al2(SO4)3

23. Transition Metals Can form more that 1 ion
d block electrons sometime act as valence
Roman numeral identifies the charge
Manganese (IV) = +4 charge
Iron (III) = +3 charge

24. Covalent Bonds Forms between Nonmetal and Nonmetal
Share valence electrons to get full octets

25. Properties of Covalent Compounds
Smallest unit called molecules (remember, ionic compounds form formula units)
The bonds between the atoms in a molecule are strong, but the attraction between the molecules is relatively weak. These attractive forces are known as intermolecular forces, or van der Waals forces.

26. Weak bonds mean: Low melting points and boiling points b/c they’re easy to split apart from each other.
compounds are soft.
Examples : H20 melts at 0.0˚C CF4 melts at –150˚ and boils at –129˚C
Tend to be be gases and liquids at room temperature

27. Covalent compounds do not conduct electricity
Many are polar
The only purely covalent bond is between atoms of the same element

28. Polar bonds
Polar bonds - a covalent bond in which the electrons are not shared equally. One atom has a greater attraction for the electrons (a greater electronegativity), so the electrons spend more time around that atom, creating a slightly negative charge. The other atom then has a slightly positive charge.

29. Polar bonds
Ex. H2O: big difference in electronegativity for oxygen and hydrogen. Oxygen pulls the electrons most of the time creating a slightly (-) charge, leaving the hydrogen with a slightly (+) charge

30. Example of a covalent bond
Hydrogen and Bromine. Hydrogen has 1 valence electron, Bromine has 7. Both need 1 more electron to form a stable noble gas configuration…so they form a single covalent bond
Use Lewis dot diagrams to show electrons, and a line to show covalent bond
H Br H – Br Or H Br

31. Oxygen and Hydrogen
H O H
H – O Or H O

32. Carbon and Chlorine:
C Cl Cl
Cl Cl – C – Cl
Cl Cl Cl

33. Carbon and Chlorine:
C Cl Cl
Cl Or Cl C Cl
Cl Cl Cl

35. Rules: drawing Lewis dot diagrams
Find central atom (fewest in number or one to the left on periodic table)
Add up total number of valence electrons (all atoms plus any charge)
Attach other atoms to central atom with 1 bonding pair
Fill octet for each outside atom
Must use up all electrons
Check Octet Rule – if needed borrow a pair of electrons to make double or triple bond

36. Try
NH3
N = 5 valence electron
H = 1
8 valence electrons total

37. Which element in the middle H – N – H H Start filling, using all 8 electrons: Remember: H valence shell is full at 2 So where will last pair be?

38. H – N – H or H

39. Multiple Covalent
Multiple Covalent bonds: sharing more than 1 pair of electrons between two atoms (double or triple bonds)
Oxygen gas, O2
O O
O=O Or O O

40. Nitrogen gas, N2
N N
N N Or N N

41. Carbon dioxide, CO2
C O O
O=C=O Or O C O

42. Try SO2 Both S & O have 6 valence electrons S = 6 O = 6
18 valence electrons total

43. Which element goes in the middle
O – S – O
Start filling with 18 electrons
Oh, don’t have enough to satisfy Octet rule
so borrow 1 pair to make a double bond

44. VSEPR: Covalent compound shapes
Valence Shell Electron Pair Repulsion
Geometric shape forms to keep electrons as far apart as possible
This shape will help determine whether molecule is polar or nonpolar
If molecule is symmetrical = nonpolar, even if individual bonds are polar.

45. VSEPR: Covalent compound shapes

46. Ionic
Covalent
Formula Unit
Smallest Unit
Molecule
Transfer Electrons
How Formed
Share Electron
Strong Bonds
Bond Strength
Weak Bonds
Repeating Patterns
Crystal Structure
Shape
Geometric Shape
VSEPR Model

47. Ionic
Covalent
Metal To Nonmetal
Forms Between
Between Nonmetals
Good Conductor When Dissolved
Conduct Electricity
Poor Conductors
Attraction Between (+) Ion and (-) Ion
Cation metals
Anion nonmetal
When Forming
Unequal Sharing
= Polar Bond
Equal Sharing
= Nonpolar Bond
High Melting and Boiling Points, Hard, Brittle Solids
Properties
Low Melting and Boiling Points, Soft, Solids, Liquids, or Gases

48. Both Ionic and Covalent
Trying to fill outer shell (valance)
Compounds are neutral overall (no charge)
Can create many different compounds
Contains more than 1 electron/atom

49. Metallic bonding
In metals the electrons are delocalized, which means they do not belong to any one atom but move freely from atom to atom. These electrons form a sea of electrons around the metal atoms. Metallic bonding is the attraction between metal atoms and the surrounding sea of electrons.

50. These freely moving electrons can act as conduct both heat and electricity which is why solid and liquid metals are good conductors.

51. Physical properties
Metallic bonding accounts for many physical properties of metals
Metals have high melting & boiling points because of the strength of the metallic bond

52. Malleability is the ability of a solid to bend or be hammered into other shapes without breaking since the electrons can slide past each other easily.
Ductility is sustaining large permanent changes in shape without breaking b/c the atoms can slide over each other easily.
Ex. A piece of metal is drawn into a wire.

53. Maleable & Ductile

54. Heat conduction (or Thermal conduction) is the transfer of energy between particles in a solid. The temperature of the material measures how fast the atoms are moving and the heat measures the total amount of energy due to the vibration of the atoms.

55. When one part of a metal is heated, the atoms in this part vibrate faster and are more likely to hit their neighbors. When collisions take place, the energy is passed on to the neighboring atoms allowing the energy to travel through the solid.

56. In general, the strength of the metallic bond depends on two factors
1. the number of electrons in the delocalized 'sea' of electrons. (More delocalized electrons results in a stronger bond and a higher melting point.)
2. packing arrangement of the metal atoms. (The more closely packed the atoms are the stronger the bond is and the higher the melting point.)