Structure and bonding

Question 1

What is electronegativity?

Answer 1

The ability of an atom to attract electrons towards itself in a covalent bond

Question 2

The further up and right you go in the periodic table, the more…

Answer 2

Electronegative an element is

Question 3

What is the most electronegative element on the periodic table?

Answer 3

Fluorine

Question 4

What scale helps to identify how electronegative an element is?

Answer 4

The Pauling Scale

Question 5

If there’s a big difference in electronegativity in a compound, what does this mean?

Answer 5

The compound will be more ionic and the bond will be more polar

Question 6

If there’s an electronegative difference of 0, what does this tell us about the molecule?

Answer 6

That it’s mostly covalent

Question 7

What’s an example of a mostly covalent molecule?

Answer 7

Cl2

Question 8

Are hydrocarbons polar or non polar?

Answer 8

Non polar

Question 9

Why is carbon dioxide non polar?

Answer 9

Because the polar bonds are arranged symmetrically and so overall there’s no polarity

Question 10

What is the strongest intermolecular force?

Answer 10

Hydrogen bonds

Question 11

What is the weakest intermolecular force?

Answer 11

London forces

Question 12

What molecules or atoms do London forces exist in?

Answer 12

All molecules and atoms with electrons

Question 13

Are more London forces existent in molecules/atoms that are bigger?

Answer 13

Yes because larger molecules/atoms have more electrons

Question 14

Which hydrocarbons have more London forces?

Answer 14

Longer, straight chained hydrocarbons

Question 15

Why do branched hydrocarbons have less London forces?

Answer 15

Because they can’t pack together as close

Question 16

What atoms/molecules are permanent dipole-dipole interactions existent in?

Answer 16

Atoms/ molecules with a polarity

Question 17

Which has weaker London forces, alkanes or alcohols?

Answer 17

Alkanes

Question 18

Do halides have permanent dipoles?

Answer 18

Yes

Question 19

What are the 3 most electronegative elements on the periodic table?

Answer 19

Nitrogen, oxygen, and fluorine

Question 20

What needs to be present for hydrogen bonding to occur?

Answer 20

Hydrogen bonded to a strongly electronegative element and at least 1 lone pair of electrons

Question 21

What must happen in order for a substance to dissolve?

Answer 21

The substance’s bonds must break, the solvent’s bonds must break, and new bonds must form between the substance and the solvent.

Question 22

Do alcohols dissolve in polar solvents?

Answer 22

Yes, because they can hydrogen bond with water molecules.

Question 23

Why can’t the hydrocarbon part of an alcohol dissolve in water?

Answer 23

Because the hydrocarbon part is non polar and so doesn’t dissolve in water

Question 24

How does the size of an alcohol affect its solubility?

Answer 24

The bigger the hydrocarbon part, the less soluble the alcohol is

Question 25

Why do some polar molecules, like haloalkanes, not dissolve in water?

Answer 25

Because their dipoles aren’t very strong and water molecules can form stronger hydrogen bonds with each other.

Question 26

What type of solvents can haloalkanes dissolve in?

Answer 26

Solvents that interact via permanent dipole-dipole interactions

Question 27

Are alkanes polar or non polar?

Answer 27

They’re non polar and they dissolve best in non polar solvents as they can form London forces between the molecules

Question 28

What is the polarising power as applied to cations?

Answer 28

The ability of a cation to change the shape of an electron cloud around an anion

Question 29

What is the strongest intermolecular force in methane?

Answer 29

London forces

Question 30

What’s the strongest intermolecular force in Hydrogen Fluoride?

Answer 30

Hydrogen bonding

Question 31

If the bond polarities don’t cancel then a molecule is what?

Answer 31

Polar

Question 32

How can you distinguish between solid lithium chloride and solid sodium chloride?

Answer 32

-Put nichrome wire in solid and place in hot/blue flame
-The lithium salt should give a chrimson colour
-The sodium salt should give a yellow colour

Question 33

What are London forces or Van Der Waals forces caused by?

Answer 33

They’re caused by the asymmetry of the electron cloud, hence causing attractive forces between neighbouring dipoles