1. Intra & Inter Molecular Forces

2. Intramolecular Forces
- are the forces that hold the atoms that make up a compound or molecule together (chemical bond)
3 Types of Intramolecular Forces (Within a molecule)
1. Ionic Bonding
2. Metallic Bonding
3. Covalent Bonding

3. * transfer of electrons from metal to non metal
1. Ionic Bonding
* transfer of electrons from metal to non metal
* the cation (+) and the anion (-) are attracted to each other through electrostatic forces

4. Properties of Ionic Compounds
High melting points and boiling points (Due to strong bonds holding the ions together)
Good Conductors of electricity (when in solution)
Hard, Rigid, Brittle solids
Tend to be soluble in water

5. * the cations are all bonded together by a sea of valence electrons
2. Metallic Bonding
* metallic solids are composed of metal atoms held together by “metal bonds”
* the electrons are delocalized because they are not bound to specific atoms
* Delocalized electrons: electrons that can move throughout the solid
* the cations are all bonded together by a sea of valence electrons

6. Properties of Metallic Bonds
moderately high melting points
high boiling points
malleable (hammered into sheets)
ductile (Able to be deformed without losing toughness)
durable
hard & strong
good thermal & electrical conductivity
Example: Metal Alloy
Alloy: mixture of a pure metal with another metal
Brass ( Cu & Zn or Cu & Sn)

7. * sharing of electrons between nonmetals
3. Covalent Bonding
* sharing of electrons between nonmetals
* the positive charge of the protons in one atoms nucleus are attracted to the negative charge of the others atoms electrons
* sharing of electrons: covalent bond

9. Bond Polarity

10. Not all covalent bonds are the same
Bond Polarity used to help describe the sharing of electrons between atoms.
Not all covalent bonds are the same
The electrons are not always equally shared

11. Types of bond polarity:
A non-polar covalent bond – is one in which the electrons are shared equally between two atoms.

12. A polar covalent bond– is one in which there is an unequal sharing of electrons between two atoms. One of the atoms exerts a greater attraction (and therefore a stronger pull) for the bonding electron than the other.

13. Properties of Covalent Compounds
relatively low melting and boiling points
poor conductors of heat
do not conduct electricity in water
soft compared to ionic compounds
tend to be more flammable than ionic compounds

14. Using Electronegativity to Determine Bond Type
To determine whether a given bond in a molecule will be non-polar covalent, polar covalent or ionic, we use electronegativity.
Electronegativity: is an atoms desire (or ability) to grab another atoms electron. The greater the atoms electronegativity, the greater its desire to attract electrons to itself. Cl H

15. Electronegativity Values:
Generally as you move horizontally from the left to the right on the periodic table the electronegativity values increase.

16. What bonds exist?
The difference of electronegativity between bonding elements indicates the type of bond that exists.
A difference greater than 2.0 = ionic bond
Ex. CaCl2 =
2.16
A difference of less than 2.0 but greater than 0.5 = polar covalent bond
Ex. HCl =
0.96
A difference less than 0.5 = non-polar covalent bond
Ex. H2 =

17. Electronegativity Video

18. Intermolecular Forces
* the forces of attraction or repulsion between neighbouring particles that aren’t actually bonded
3 Types of Intermolecular forces (between molecules)
1. Van Der Waals Forces
a) Dispersion Forces (London Forces)
b) Dipole Dipole Forces
c) Hydrogen Bonding
2. Ionic Crystal
3. Network Covalent Crystals

19. 1. Van der Waals Forces
* They are attractive forces between covalent molecules.
* The type of intermolecular forces depends on whether the molecule is polar or non-polar

20. SCOTCH TAPE a) Dispersion forces (London forces)
Types of intermolecular forces (Van der Waals forces):
a) Dispersion forces (London forces)
exist between all covalent molecules
dispersion of the electrons causes a Dipole Moment
Dipole: refers to the unequal sharing of electrons with in a covalent molecule (causing a slight negative and slight positive)
they are very weak forces
SCOTCH TAPE

21. MASKING TAPE 2. Dipole-Dipole forces
When the dipoles of polar covalent molecules position their positive and negative ends near each other and some electrostatic attraction occurs
Stronger attraction than Dispersion Forces
MASKING TAPE

22. DUCT TAPE 3. Hydrogen Bonds
a strong force that occurs when a H atom is bonded to a highly electronegative atom (O, N or F) and comes in close contact and is attracted to a nearby partially negative atom or molecule
DUCT TAPE

23. Properties of Vander Waals Forces
the stronger the bond the higher the melting point, boiling
point and surface area
Bond strength increases from London Dispersion to Dipole Dipole to H Bonding

24. 2. Ionic Crystal
- Ionic Bonds technically form individual ions that attract together in a specific pattern
- Crystal Lattice: a 3 dimensional network of positive and negative ions held together by attraction
Example: Salt

25. Properties of Ionic Crystals Soluble in water
the are good conductors of electricity when in solution
Hard & Brittle
High melting and boiling points

26. 3. Network Covalent Crystals
* Covalent bonds form an interwoven network
* most are mad up of Carbon and Silicon
Example: Diamond & Graphite

27. Properties of Network Covalent Crystals
Very high melting and boiling points
Extreme Hardness
Poor conductors
insoluble