Ozone: Intermolecular Forces Flashcards
Definition of electronegativity
Ability of an atom to attract a shared pair of electrons to itself
What two factors affect electronegativity
- Nuclear charge
2. Atomic radius
How does nuclear charge affect electronegativity
Increased nuclear charge = increased electronegativity
How does atomic radius affect electronegativity
Decreased atomic radius = increased electronegativity
What do you atoms with similar electronegativities form
Give examples
Non-polar bonds
Eg. Cl2 , O2, I2
What do you atoms with a big difference in electronegativity form
Polar bonds
Eg. H-Cl ( delta +ve H & delta -ve Cl )
H-O-H ( delta +ve H’s & delta -ve O )
What causes POLAR molecular polarity
Unequal charge distribution
Eg. Cis Z ( CHCl=CHCl ) —> 2 delta +ve H on top and 2 delta -ve Cl on bottom
- CH3Cl —> 3 delta +ve H and 1 delta -ve Cl
What causes NON-POLAR molecular polarity
equal charge distribution
Eg. Trans E ( CHCl=CHCl ) —> 1 delta +ve H on top & 1 on bottom and 1 delta -ve Cl on top & 1 on bottom
- CCl4 —> 4 delta -ve Cl
What are the 3 main types of intermolecular forces
- Permanent dipole-permanent dipole interactions
- Instantaneous dipole induced dipole interactions
- Hydrogen bonding
Definition of a permanent dipole permanent dipole interactions
When attraction occurs between the partial positive ( delta +ve ) and negative ( delta -ve ) charges of neighbouring molecules
Be able to draw a diagram showing the permanent dipole percent dipole interactions in hydrogen chloride
Look at sheet
Definition of instantaneous dipole induced dipole interactions
- Relatively weak forces that increase in strength as the size of a molecule or atom increases
- Occur between atoms or molecules without permanent dipole is e.g. hydrocarbons
Be able to draw a diagram showing instantaneous dipole induced dipole using two chlorine molecules
Look at sheet
Definition of hydrogen bonding
Strongest type of intermolecular attractive force
What three what three Bondings does hydrogen bonding only occur in
- H-O
- H-N
- H-F
Be able to draw a diagram of hydrogen bonding in water
hint = looks like mike mouse
Look at sheet
State and explain to anomalous properties of ice caused by hydrogen bonding
- Ice is less dense than water
- molecules in ice held apart by hydrogen bonds
- ice has an open lattice - Ice has a relatively high melting point
- hydrogen bonds are relatively strong
- hydrogen bond stronger than other intermolecular forces
- more energy needed to overcome hydrogen bonding
Explain the difference in density of liquid water and ice in terms of intermolecular bonds ( 6 )
- Both have hydrogen bonding
- Loan pair on oxygen…
- Bonds to hydrogen with delta +ve charge on another molecule
- Ice is less dense because
- molecules get further apart
- more ape structure ( more air between molecules ) - Intermolecular bonds keep ice in a lattice
- For same number of water molecules ice takes up more space than liquid water leading to lower density of ice
