Bonding and Types of Substance (1+2)

Question 1

What are

ions?

Answer 1

charged particles

Question 2

What are

cations?

Answer 2

positive ions that form when atoms lose electrons

so they have more protons than electrons

Question 3

What are

anions?

Answer 3

negative ions that form when atoms gain electrons

so they have more electrons than protons

Question 4

What does an ion name ending in

-ate

mean?

Answer 4

the ion is negative and contains oxygen and at least one other element

Question 5

What does an ion name ending in

-ide

mean?

Answer 5

the ion is negative and contains only one element

hydroxide is an exception

Question 6

Define

ionic bond.

Answer 6

the electrostatic attraction between two or more oppositely charged ions

Question 7

What is the

structure of ionic compounds?

Answer 7

a giant ionic lattice

• the electrostatic attraction between oppositely charged ions results in positive ions being immediately surrounded by negative ions, and negative ions being immediately surrounded by positive ions
• these ions are held together by strong electrosatic forces
• these forces act in all directions to form a giant lattic structure

Question 8

What are the positives and negatives of

dot and cross diagrams?

(when representing ionic compounds) (1+, 2-)

Answer 8

+useful for showing how ionic compound are formed and where the electrons in the ions come from
-don’t show the structure of the compound
-don’t show the relative sizes of the ions or how they’re arranged

Question 9

What are the positives and negatives of

3D models?

(when representing ionic compounds) (2+, 1-)

Answer 9

+show the relative sizes of ions
+show the regular pattern of ions
-only let you see the other layer of the compound

Question 10

What are the positives and negatives of

ball and stick models?

(when representing ionic compounds) (4+, 1-)

Answer 10

+show the regular pattern of ions
+show how the ions are arranged
+show that the lattice extends beyond what is shown in the diagram
+can show the relative sizes of the ions (if drawn to scale)
-suggest that there are gaps between the ions (which there aren’t)

Question 11

What are some properties of

ionic compounds?

(melting and boiling points, solubility, electrical conductivity)

Answer 11

• high melting and boiling points
• (mostly) dissolve easily in water
• don’t conduct electricity when solid
• do conduct electricity when molten or aqueous

Question 12

Explain

melting and boiling points

in relation to ionic compounds.

Answer 12

They have high melting and boiling points due to the strong electrostatic attraction between ions. It takes a large amount of energy to overcome this attraction and break the many strong bonds.

Question 13

Define

electrical current.

Answer 13

the flow of charged particles

this can either be ions or delocalised electrons

Question 14

Explain

electrical conductivity

in relation to ionic compounds.

Answer 14

Ionic compounds cannot conduct electricity when solid because the ions are all held in fixed positions and cannot move. When the compound is molten or aqueous, the ions are free to move and they can carry electric charge.

Question 15

Define

covalent bond.

Answer 15

the electrostatic attraction between a shared pair of electrons and the nuclei of the two bonded atoms

Question 16

What is a

displayed formula?

Answer 16

a two-dimensional representation of a molecule that shows the covalent bonds as single lines between atoms

Question 17

What are the positives and negatives of

dot and cross diagrams

when representing covalent bonding? (1+, 2-)

Answer 17

+show which atoms the electrons in a covalent bond come from
-don’t show the relative sizes of the atoms
-don’t show how the atoms are arranged in space

Question 18

What are the positives and negatives of

displayed formulas

when representing covalent bonding? (2+, 3-)

Answer 18

+show what atoms something contains
+shows how they are connected in large molecules
-don’t show the 3D structure of the molecule
-don’t show which atoms the electrons have come from
-don’t show the correct scales of the atoms

Question 19

What are the positives and negatives of

ball and stick models

when representing covalent bonding? (3+, 4-)

Answer 19

+show the atoms in a molecule
+show how the atoms are arranged in space
+show the bonds as well as the atoms
-get confusing for large molecules that contain lots of atoms
-make it look like there are big gaps between the atoms
-don’t show where the electrons have come from
-sometimes the atoms are not drawn to scale

Question 20

Define

simple molecule.

Answer 20

a molecule that is made up of only a few atoms joined by covalent bonds

Question 21

What is the general size of a

simple molecule?

Answer 21

1 x 10^-10 m

Question 22

Explain

electrical conductivity

in relation to simple molecules.

Answer 22

simple molecules don’t conduct electricity in any state as there are no ions or delocalised electrons so nothing can carry an electrical charge

Question 23

Explain

melting and boiling points

in relation to simple molecules.

Answer 23

simple molecular substances have low melting and boiling points because although there are very strong covalent bonds between the atoms within molecules, there are very weak intermolecular forces between the molecules

it’s only the weak intermolecular forces that need to be overcome to change the state of a simple molecular substance - not the stronger covalent bonds
so overcoming these weak intermolecular forces doesn’t take much energy

Question 24

How do melting and boiling points vary for

simple covalent molecules that are increasing in size?

and why?

Answer 24

As molecules get bigger, the strength of the intermolecular forces increases. So, more energy is needed to break them, and the melting and boiling points increase.

Question 25

# What are polymers?

Answer 25

molecules made up of long chains of covalently bonded carbon atoms

Question 26

# What is one use of the polymer poly(ethene)?

Answer 26

plastic film for wrapping and packaging

Question 27

# What are the general characteristics of giant covalent structures? ## Footnote - type of bonds? - melting and boiling points? - conductivity? - solubility?

Answer 27

- atoms are joined by covalent bonding - have very high melting and boiling points - don't conduct electricity (graphite and graphene are exceptions) - not soluble in water

Question 28

# What are the specific characteristics of diamond? | and one use? ## Footnote - type of atom? - how many bonds? - rigidity? - melting and boiling points? - conductivity?

Answer 28

- made up completely of carbon atoms - each carbon atom is bonded to four others - very rigid - very high melting and boiling points - doesn't conduct electricity | used to strengthen cutting tools (e.g. saw teeth and drill bits)

Question 29

# What are the specific characteristics of graphite? | and one use? ## Footnote - type of atom? - how many bonds? - softness? - melting and boiling points? - conductivity?

Answer 29

- made up completely of carbon atoms - each carbon atom is bonded to three others - soft and slippery - high melting and boiling points - can conduct electricity | used as a lubricating material

Question 30

# Why is graphite a good lubricant?

Answer 30

Graphite is composed of sheets of carbon atoms arranged in hexagons. There aren't any covalent bonds between the layers - they're held together by intermolecular forces, so are free to move over eachother.

Question 31

# What are the specific characteristics of graphene? | and one use? ## Footnote - type of atom? - how many bonds? - strength? - melting and boiling points? - conductivity?

Answer 31

- made up completely of carbon atoms - each carbon atom is bonded to three others - very strong and lightweight - high melting and boiling points - can conduct electricity ## Footnote can be added to composite materials to improve their strength, can be used in electronics

Question 32

# Tell me about buckminsterfullerene. ## Footnote - molecular formula? - form? - stability? - appearance? - conductivity?

Answer 32

- has the molecular formula of C60 - forms a hollow sphere containing 20 hexagons and 12 pentagons - stable giant covalent molecule - forms soft brown-black crystals - semi-conductor

Question 33

# Tell me about nanotubes. ## Footnote - form? - size? - conductivity?

Answer 33

- a type of fullerene which are tiny carbon cylinders - high length to diameter ratio - good conductor (of both heat and electricity)

Question 34

# What are three uses of fullerenes?

Answer 34

- medicine - as catalysts - strengthening materials

Question 35

# How can fullerenes be used in medicine?

Answer 35

They can be used to 'cage' other molecules by forming around another atom or molecule, which is then trapped inside. | This could be used to deliver a drug to where it is needed

Question 36

# How can fullerenes be used as catalysts?

Answer 36

They have a huge surface area so they could help make great industry catalysts. | Individual catalyst molecules could be attached to the fullerenes

Question 37

# What does it mean to have high tensile strength?

Answer 37

the object does not break when stretched

Question 38

# How can fullerenes be used for strengthening materials?

Answer 38

they have high tensile strength so can be used to strengthen materials without adding much weight ## Footnote e.g. can be used to strengthen sports equipment that needs to be strong but also lightweight, such as tennis raquet frames

Question 39

# What is the structure of metals?

Answer 39

It is a giant structure of positive metal ions arranged in a regular pattern. The ions are closely packed. The delocalised electrons form a sea around the ions and are free to move throughout the structure. ## Footnote There are strong forces of electrostatic attraction between the ions and the electrons. These forces hold the metal structure together.

Question 40

# Define metallic bonding.

Answer 40

the electrostatic forces of attraction between positive metal ions and negative electrons

Question 41

# Explain melting and boiling points | in relation to metals.

Answer 41

Metals have high melting and boiling points as the electrostatic forces between the metal ions and the delocalised sea of electrons are very strong, so need lots of energy to be broken. | This means that they're generally shiny solids at room temperature.

Question 42

# Explain conductivity | in relation to metals.

Answer 42

Metals can conduct as they have delocalised electrons that are free to move through the whole structure. This also means that they are much better conductors of thermal energy and electricity than most non-metals. | Electrons carry the current or the thermal energy through the structure.

Question 43

# Explain malleability | in relation to metals.

Answer 43

Metals are malleable as the layers of metal atoms are able to slide over each other. | This means that they can be hammered or rolled into flat sheets

Question 44

# Explain density | in relation to metals.

Answer 44

Metals generally have a higher density than non-metals. This is because the ions in the metallic structure are packed close together and there aren't many gaps in the structure as in non-metals.