Bonding and Structure

Question 1

How do ionic bonds arise?

Answer 1

When the difference in electronegativity is so large that one element has a much stronger attraction for boding electrons than the other.

Question 2

How do pure covalent bonds arise?

Answer 2

When the electronegativities of two atoms are identical and the bonding electrons are evenly shared between both atoms

Question 3

How do polar covalent bonds arise?

Answer 3

When there is a small difference in electronegativities and the electrons are shared unequally

Question 4

What is the order of the types of bonding on the bonding continuum?

Answer 4

Pure covalent, polar covalent, ionic bonding

Question 5

What is a dipole?

Answer 5

A bond or molecule whose ends have opposite charges

Question 6

If the shape of the molecule is symmetrical, would it be polar or non-polar?

Answer 6

It would be non-polar

Question 7

Which liquid does the charged rod affect in the charged rod experiment?

Answer 7

The charge in the rod only affects the polar liquid because they contain a permanent dipole

Question 8

What are intermolecular forces?

Answer 8

The forces between molecules

Question 9

What are intramolecular forces?

Answer 9

The forces between atoms in a single molecule

Question 10

What are the ‘Van Der Waals’ forces?

Answer 10

1. London dispersion forces (LDF’s)
2. Permanent dipole-permanent dipole (PDPD)
3. Hydrogen bonding

Question 11

How do London dispersion forces arise?

Answer 11

Due to an uneven distribution of electrons, which forms a temporary dipole. The slight charges in the dipole include opposite charges in neighbouring atoms, which are called induced dipoles.
The attraction between opposing charges are known ad LDF’s

Question 12

What is the relationship between LDF’s and the number of electrons in an atom or molecule?

Answer 12

The more electrons there are, the stronger the LDF’s are. Larger atoms contain more electrons and therefore have stronger LDF’s between them.

Question 13

What are PDPD interactions?

Answer 13

Additional electrostatic forces of attraction between oppositely charged ends of polar molecules (they are an addition to LDF’s)

Question 14

How do PDPD interactions arise?

Answer 14

If a molecule has a permanent dipole, it has PDPD interactions

Question 15

How does hydrogen bonding arise?

Answer 15

When a hydrogen atom is bonded to a strongly electronegative element such as fluorine, oxygen or nitrogen.

Question 16

What is the effect of LDF’s on the melting and boiling points of molecules?

Answer 16

The larger the molecule, the stronger the LDF’s are, making it harder to break down bigger molecules

Question 17

What is the effect of PDPD interactions on the melting and boiling points of molecules?

Answer 17

Polar molecules have higher boiling points than non-polar molecules due the PDPD interactions. This is because PDPD interactions are stronger than LDF’s

Question 18

What is the effect of hydrogen bonding on the melting and boiling points of molecules?

Answer 18

Molecules containing hydrogen bonding have high melting and boiling points due to their high electronegativities

Question 19

What are the types of bonding present in elements?

Answer 19

Covalent molecular
Covalent network
Metallic
Monatomic

Question 20

What is a discrete molecule?

Answer 20

A covalent molecule

Question 21

What molecules are covalent molecular?

Answer 21

1. Diatomic elements: Hydrogen, Nitrogen, Fluorine, Oxygen, Iodine, Chlorine, Bromine
2. Phosphorus P4, Sulphur S8, Fullerene C60

Question 22

How are covalent networks formed?

Answer 22

When atoms join together to form a very large structure with no definite size

Question 23

What molecules are covalent networks?

Answer 23

Carbon (as graphite or diamond), Silicon, Boron

Question 24

What molecules are metallic?

Answer 24

All elements have a metallic lattice structure. They are also all solids at room temperature

Question 25

What molecules are monatomic

Answer 25

The noble gases

Question 26

what does the prefix ‘mono’ in monatomic tell us?

Answer 26

That monatomic elements contain single atoms and are not bonded to any other atoms