types of intermolecular forces

Question 1

what is an intermolecular force?

Answer 1

The force between the actual molecules.

Question 2

what is a permanent dipole - dipole force?
In which type of molecules do these forces happen?

Answer 2

when there is a permanent attracting force between the charges of two molecules, we call it a dipole - dipole force.

They only happen in molecules that contain a permanent dipole, so technicly, they occur between polar molecules only.

Question 3

What determines how strong a permanent dipole - dipole force is?

Answer 3

The charge difference in a covalent bond.
As charge difference in a covalent bond increases, the dipole force, also increases.

Question 4

state what is meant by the term hydrogen bonding.

Answer 4

Whenever theres a bond between Nitrogen and hydrogen, oxygen and hydrogen, and flourine and hydrogen. We call these types of bonds, hydrogen bonds.

Question 5

What are wan der waals forces? (Include the word temporary dipole - dipole in your answer)

Answer 5

They arise when the movement of electrons in one molecule, creates a temporary dipole. This induces a temporary dipole in a nearby molecule

This results in attraction between partial charges of nearby molecules.

Question 6

All polar molecules experience both wan der waals forces, and permanent dipole - dipole forces.

TRUE OR FALSE?

Answer 6

TRUE

Question 7

Which type of substances, can have van der waals forces?

Answer 7

1. Non - polar ones.
2. polar ones.
3. elements that exist as single atoms.

Question 8

What happens to van der waal forces as we go down a group? relate your answer to melting an boiling points.

Answer 8

As we go down a group, the number of electrons increases, therefore there are more wan der waals forces, which means it requires more energy to break them, thus higher melting and boiling points.

Question 9

What is the order of forces? from strongest to weakest

Relate this to the melting and boiling points of atoms.

Answer 9

1. Hydrogen bonding
2. Permanent dipole - dipole forces.
3. wan de waals forces ( induced dipole -dipole forces)

The weaker the force, the weaker the intermolecular force, thus, the lower the melting and boiling point.

Question 10

Explain why some moleculesdissolve in water, and why some dont in terms of intermolecular forces.

Answer 10

Polar molecules dissolve in polar molecules, because it is easier to replace in intermolecular bonds between the two actual atoms.

Non polar molecules, dissolvein non - polar molecules, for the same reason.

Question 11

Explain why ice is less denser than water?

Answer 11

Because in ice, the hydrogen bonds, hold the water molecules further away from each other.
This means that if we were to have water an ice, with the same number of molecules, then ice would take up a larges volume of space. thus being less dense.