Intermolecular forces

Question 1

What are intermolecular forces?

Answer 1

Forces occurring between molecules

Question 2

Where do intermolecular forces only occur in?

Answer 2

Simple covalent substances

Question 3

What are the bonds called that hold together atoms by a shared pair of electrons?

Answer 3

Covalent bonds

Question 4

What are the 3 types of intermolecular forces?

Answer 4

Induced dipole dipole
Permanent dipole dipole
Hydrogen bonding

Question 5

Are induced dipole dipole forces temporary or permanent?

Answer 5

Temporary

Question 6

What type of molecules do induced dipole dipole forces occur between?

Answer 6

All molecules

Question 7

Why do induced dipole dipole forces act for a short time?

Answer 7

Electron density is constantly changing

Question 8

Are induced dipole dipole forces strong or weak?

Answer 8

Weakest type of intermolecular force

Question 9

What type of forces interact through symmetrical molecules/non-polar molecules?

Answer 9

Induced dipole dipole interactions

Question 10

Why does the boiling point increase when there are induced dipole dipole forces?

Answer 10

More energy is needed to disrupt the forces between the molecules

Question 11

How do induce dipole dipole interactions arise?

Answer 11

Electrons in a molecule are constantly moving
Electron distribution may be unsymmetrical at any one instant
produces a temporary dipole in that molecule
if another molecule approaches the molecule with the c5::temporary dipole, an opposite dipole is induced into the neighbouring molecule

Question 12

What two factors increase the strength of induced dipole dipole interactions?

Answer 12

Increase in the number of electrons in the molecule or atom
Increase in the surface contact of the molecules or atoms

Question 13

What are polar bonds?

Answer 13

Covalent bond between atoms with different electronegativity

Question 14

What is definition of electronegativity?

Answer 14

The ability of an atom to attract the bonding electrons in a covalent bond

Question 15

what results in the differences in electronegativity?

Answer 15

A dipole is the separation of charge in a bond which occurs

Question 16

When does electronegativity increase?

Answer 16

Across a period

Question 17

When does electronegativity decrease?

Answer 17

Down a group

Question 18

What element has the highest electronegativity?

Answer 18

Fluorine

Question 19

What element has the lowest electronegativity?

Answer 19

Francium

Question 20

What are polar molecules?

Answer 20

Unsymmetrical molecules whose dipole don’t cancel out

Question 21

Where do electrostatic forces of attraction act between in polar molecules?

Answer 21

Opposite charges of the neighbouring molecules

Question 22

What will happen to the overall permanent dipole if the molecule is symmetrical?

Answer 22

Dipoles will cancel each other out
There will be no overall permanent dipole
Molecule is now non-polar

Question 23

Do symmetrical molecules have any lone pairs on the central atom?

Answer 23

No

Question 24

Are all the atoms around the central atom the same or different in symmetrical molecules?

Answer 24

Same

Question 25

What happens when dipoles cancel out in a symmetrical molecule?

Answer 25

Molecule has no overall dipole

Question 26

In the central atom of an unsymmetrical molecule, how many atoms are attached to it?

Answer 26

2 or more different atoms

Question 27

Do unsymmetrical molecules have any lone pairs on the central atom?

Answer 27

Yes
1 or more lone pairs

Question 28

What happens when the dipole do not cancel each other out in an unsymmetrical molecule?

Answer 28

It has an overall dipole

Question 29

What is the definition of hydrogen bonding?

Answer 29

Intermolecular force between the lone pair of a N, O or F of an NH, OH, or FH with the H atom of NH, OH or FH in a neighbouring molecule

Question 30

What are the 3 most electronegative atoms?

Answer 30

Nitrogen
Oxygen
Fluorine

Question 31

Because of the large difference in electronegativity between a hydrogen atom & either an N, O or F atom, what is formed?

Answer 31

Very polar bonds are formed

Question 32

Does hydrogen have a strong partial charge (δᐩ)?

Answer 32

Yes

Question 33

Give the order of strength of intermolecular forces

Answer 33

Hydrogen bonding
Permanent dipole dipole
Induced dipole dipole