Intermolecular Forces

Question 1

Intramolecular forces

Answer 1

• Forces that physically keep substances together
• Ionic and molecular bonds
• Determines the chemical behaviors of a substance

Question 2

Intermolecular force

Answer 2

• Attraction between molecules
• Ionic molecules do not form intermolecular bonds

Question 3

Importance of intermolecular forces

Answer 3

• Molecular compound properties can not be explained just through covalent bonds
• If covalent bonds were the only forces, molecular compounds would be gasses
• This is because the molecules are not strong enough to hold them to solids or liquids
• They are not interacting (intermolecular bonds)

Question 4

Trend of Intermolecular forces

Answer 4

• When intermolecular forces between molecules in molecular compound increase (held tighter and closer), the compounds melting, boiling and surface tension also increase

Question 5

Electrostatic forces

Answer 5

• Full charges you need to separate, which makes it difficult
• Forces made by Ionic crystal

Question 6

Molecular polarity

Answer 6

Used molecular polarity determines what the molecule can do

Question 7

Dipole-Dipole Force

Answer 7

• Polar has different ends
• If you have another molecular, the opposites sides will attract
• It does not have to be the same molecular (has to be a pure substance)

Question 8

Hydrogen bond

Answer 8

• When hydrogen is bonded on the FON
• Type of dipole-dipole force

Question 9

Ion-Dipole Force

Answer 9

• The polar molecule is attracted to the cation/anion
• The opposite side get attracted

Question 10

The strength of Ion-Dipole force depends

Answer 10

charge and size of the ion
- Cations are stronger due to being smaller (concentrated energy)
Magnitude of diploid
- You can find the strength by finding electronegativity of atoms

Question 11

London Dispersion Force

Answer 11

• All molecules have this intermolecular force
• Only temporary (happens for a second)

Question 12

How does London Dispersion Force work

Answer 12

Electrons move around in molecules and can move to one side of molecules
* This forms temporary dipoles
* This induces other molecules to form temporary diploses (due to attraction)
* This creates a temporary attraction to all molecules in a compound

Question 13

2 factors to determine strength of LD force

Answer 13

Number of electrons
- Greater electrons= more chance of forming temporary dipole= stronger LD force
Shape of the molecules
- More elements in linear shape, more surface area with adjacent molecules = stronger LD force

Question 14

Intermolecular Forces & States

Answer 14

• Responsible for different states of matter
• Stronger intermolecular forces= high melting/boiling point
• Liquids and gasses are able to move more freely (less interactions)
• Must have enough kinetic energy to break intermolecular forces (energy/temp), allowing more space

Question 15

Intermolecular Forces & Water Solubility

Answer 15

• Water must interact with polar molecular or ion to dissolve
• Oxygen with cation and hydrogen with anion

Question 16

Water in different forms

Answer 16

Water is less dense as a solid than liquid
* When water freezes, molecules lose kinetic energy and slow down
* Molecules are able to interact with each other and form hydrogen bonds
* Hydrogen bonds will arrange in crystal structure
* This creates more space between molecules
* Liquid molecules are more closer because the solid forms hydrogen bonds

Question 17

Water and surface tension

Answer 17

• Hydrogen bonds in water hold strongly and pull together
• This resist them from breaking and creates a shape to create smaller surface area
• This is because they want to be closer together (hydrogen bonds)

Question 18

Strongest forces

Answer 18

• Hydrogen bonding
• Dipole dipole
• London dispersion