Bonding

Question 1

What are the properties of ionic compounds

Answer 1

Very high melting and boiling points - a lot of energy to break strong electrostatic forces
Soluble in polar solvents such as water
Don’t conduct electricity when solid - ions are locked in place by electrostatic forces of attraction; ions can’t move so they can’t carry a charge
Can conduct electricity when molten or liquid

Question 2

Why do ionic compounds dissolve in polar solvents such as water

Answer 2

The polar molecules surround the ions and overcome the electrostatic attraction between the ions

Question 3

What type of bonding takes place when a two non-metals react

Answer 3

Covalent bonding

Question 4

What is a dative bond

Answer 4

When an atom uses a lone pair of electrons to form a covalent bond

Question 5

What is another word for a dative bond

Answer 5

A coordinate bond

Question 6

What does a dative bond look like in displayed formula

Answer 6

An arrow pointing away from the atom with the lone pair

Question 7

Is there any change in strength between a dative bond and a covalent bond

Answer 7

No
They have the same strength

Question 8

What would the bonding structure and angle be of this compound

Answer 8

Linear
Bond angle would be 180 degrees

Question 9

What would the bonding structure and angle be of this compound

Answer 9

Trigonal planar
Bond angle would be 120 degrees

Question 10

Give an example of a tetrahedral molecule

Answer 10

Methane

Question 11

What is electron pair repulsion theory

Answer 11

The shape of a molecule is determined by the electron pairs surrounding the central atom
Electron pairs repel each other so they try to get further away from each other as possible

Question 12

What is electronegativity

Answer 12

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

Question 13

What is the trend of electronegativity in the periodic table

Answer 13

Increases from left to right and bottom to the top

Question 14

What three factors affects electronegativity

Answer 14

The size of the positive charge on the nucleus
The atomic radius
The shielding of the nucleus

Question 15

What is a dipole

Answer 15

A difference in charge between the two atoms caused by a shift in electron density in the bond

Question 16

How do you show that a bond is polar

Answer 16

Put deltas on the elements

Question 17

What is stronger, IMF or covalent bonds

Answer 17

Covalent bonds are much stronger

Question 18

What are the three types of IMF

Answer 18

Induced dipole-dipole interactions/van der Waals forces
Permanent dipole-dipole interactions
Hydrogen bonds

Question 20

What are induced dipole-dipole interactions

Answer 20

There’s random movement of electrons
At any point there could be more electrons on one side of the atom than the other
This causes a delta negative charge on that side and a delta positive charge on the other side
The negative charge causes the electrons in the neighbouring atom to be repeled causing a dipole in that atom as well
This is an induced dipole-dipole interaction

Question 21

What are the three IMF

Answer 21

Induced dipole-dipole interactions
Permanent dipoles
Hydrogen bonding

Question 22

What are induced dipole-dipole interactions also known as

Answer 22

van der Waals forces , London forces or dispersion forces

Question 23

What is the relative strength of van der Waals forces or induced dipole-dipole interactions

Answer 23

They are weak and much weaker than covalent bonds

Question 24

What type of bonds experience van der Waals forces

Answer 24

All bonds experience van der Waals forces even if they experience other IMF aswell

Question 25

Describe and explain the relationship between the number of electrons an atom has and the boiling point it has

Answer 25

As the number of electrons increase then the boiling point increases This is because the van der Waals forces increase in strength because there are more electrons

Question 26

What is permanent dipole

Answer 26

If one atom is more electronegative than the other in a bond than the electrons will be more drawn to it This will make that atom more negatively charged than the other one When two molecules with this get close enough then the permanent dipoles can lead to an attraction like this

Question 27

Trichloromethane has permanent dipoles Explain why trichloromethane has a lower boiling point than tetrachloromethane

Answer 27

Because there are also van der Waals forces affecting the boiling point Tetrachloromethane has more electrons so it will have stronger van der Waals forces and will have a higher boiling point

Question 28

Why doesn't this molecule has permanent dipoles

Answer 28

Symmetrical bond so dipoles cancel each other out

Question 29

What is the relationship between the strength of a permanent dipole and the number of electrons present in a bond

Answer 29

As the number of electrons in a bond increases the strength of the permanent dipole decreases because the electronegativity decreases This because of factors like shielding and atomic radius

Question 30

What is hydrogen bonding

Answer 30

When hydrogen is bonded to a very electronegative element and the neighbouring identicle molecule's hydrogen bonds to a lone pair on the electronegative element that hydrogen is bonded to

Question 31

What are the three elements that can form hydrogen bonds with hydrogen and why are they able to form hydrogen bonds

Answer 31

Nitrogen Fluorine Oxygen All have at least one lone pair and they all very electronegative

Question 32

Which IMF is the strongest

Answer 32

Hydrogen bonding

Question 33

How does hydrogen bonding affect the properties of water

Answer 33

Has high melting and boiling point Have higher density when liquid than solid

Question 34

Why does water have higher density in liquid form rather than solid form

Answer 34

In liquid form the molecules are moving randomly and hydrogen bonds are being formed and broken When they are cooled the molecules slow down and arrange themselves in a more ordered network of hydrogen bonds This structure causes the molecules to be further apart than in liquid form

Question 35

What is a simple molecule

Answer 35

They consist of covalent bonds and they have small molecules with a fixed number of atoms

Question 36

Give two examples of giant covalent structures

Answer 36

Diamond Graphite

Question 37

Describe and explain the melting and boiling points of simple molecular substances

Answer 37

Only have induced dipole-dipole interactions which are very weak IMF causing them to have low boiling and melting points

Question 38

What does the solubility of a simple molecular substance depend on

Answer 38

Whether it is polar or non-polar

Question 39

What are the four general rules when it comes to solubility of simple molecular substances

Answer 39

Non-polar substances dissolve very well in non-polar solvents - this is because the solvent molecules form van der Waals forces to the non-polar molecules Non-polar substances are usually insoluble in polar solvents because the atoms in the solvent are attracted to each other since they have different charges Polar substances dissolve in polar solvents Polar substances are usually insoluble in non-polar solvents

Question 40

Can simple molecular substances conduct electricity and why

Answer 40

Don't contain mobile charged ions so they can't conduct electricity