bonding and Structure

Question 1

How do elements react?

Answer 1

They form bonds with each other after they’ve reacted, share electrons, or gain/lose outer electrons.

Question 2

What do ionic compounds contain?

Answer 2

Metal and non-metal atoms.

Question 3

What do covalent compounds contain?

Answer 3

Non-metal atoms only.

Question 4

What is an ionic bond?

Answer 4

Attraction between oppositely charged ions.

Question 5

What is a covalent bond?

Answer 5

Two shared electrons between two atoms.

Question 6

Why do ionic compounds conduct when molten or as a solution?

Answer 6

They’re liquids so ions can move freely.

They have charged particles which pass on the energy.

Question 7

Why do elements react together?

Answer 7

Because they gain or lose outer electrons to get a full outer shell.

Question 8

Why do ionic compounds have high melting/boiling points?

Answer 8

Because there’s a strong bond between ions and need a lot of energy to be broken.

Question 9

What properties do particles need to have to conduct electricity?

Answer 9

Particles must be able to move freely.

Particles must have a charge.

Question 10

Why don’t simple covalent substances conduct electricity?

Answer 10

Because they don’t lose/gain electrons - only share them - so there are no charged particles to conduct the energy.

Question 11

Why do simple covalent substances have low melting/boiling points?

Answer 11

Because the intermolecular forces are weak even though covalent bonds are strong.

Question 12

What are macromolecules?

Answer 12

Giant covalent structures.

Question 13

Does diamond conduct?

Answer 13

No because there are no charged particles to carry the charge.

Question 14

What are diamond’s melting and boiling points like?

Answer 14

High because they have covalent bonds only which are hard to break.

Question 15

How many carbon atoms is each one covalently bonded to in diamond?

Answer 15

4.

Question 16

Why is diamond hard to break?

Answer 16

Because they are all covalent bonds - no intermolecular forces.

Question 17

Does graphite conduct?

Answer 17

Yes because there is one free electron which is free to move per molecule.

Question 18

What is graphite’s boiling and melting point like?

Answer 18

High because it has covalent bonds and intermolecular forces.

Question 19

Which has a lower melting point, graphite or diamond? Why?

Answer 19

Graphite because it only has 3 covalent bonds per atom (diamond has 4 per molecule).

Question 20

Why is diamond the hardest substance on earth?

Answer 20

It has all covalent bonds.

Question 21

Why is graphite soft and slippery?

Answer 21

Because the layers can glide over each other because the weak intermolecular forces are easily broken.

Question 22

Formula of buckminster fullerene?

Answer 22

C60.

Question 23

How are the carbon atoms bonded in buckminster fullerene?

Answer 23

Each carbon atom bonds to 3 others with two forming single bonds and one a double bond.

Question 24

What does silicon dioxide have a similar structure to?

Answer 24

Diamond.

Question 25

What structure do diamond and silicon dioxide have?

Answer 25

Tetrahedral.

Question 26

Particles in ionic compounds?

Answer 26

Ions.

Question 27

Particles in metallic compounds (metallic bonding)?

Answer 27

Positive ions and delocalised electrons.

Question 28

Particles in giant covalent compounds?

Answer 28

Atoms.

Question 29

Particles in simple molecular covalent compounds?

Answer 29

Molecules.

Question 30

What bonds atoms together in metals?

Answer 30

The strong electro-static attraction between negatively charged electrons and positively charged atoms.

Question 31

How are the ions arranged in a metal?

Answer 31

In regular layers.

Question 32

Properties of metals?

Answer 32

Shaped because the layers slide over each other. ## Footnote Conducts as outer electrons are delocalised. ## Footnote High melting point as there are strong bonds between ions and electrons.

Question 33

What are alloys?

Answer 33

Mixtures where other atoms are added to metals.

Question 34

Why are alloys stronger than pure metal?

Answer 34

The layers are irregular so it’s harder for atoms to slide over each other.

Question 35

What is ethane an example of?

Answer 35

A monomer.

Question 36

What is polyethane an example of?

Answer 36

A polymer.

Question 37

What are monomers?

Answer 37

Small molecules.

Question 38

What are polymers?

Answer 38

Large molecules.

Question 39

How do polymer chains slide past each other?

Answer 39

Due to weak intermolecular forces.

Question 40

What is graphene?

Answer 40

A thin layer of carbon.

Question 41

What do several layers of graphene form?

Answer 41

Graphite.

Question 42

What are fullerenes?

Answer 42

Large molecules of allotropes of carbon arranged in balls, cages or tubes.

Question 43

What was the first fullerene discovered?

Answer 43

Buckminster Fullerene.

Question 44

What are fullerenes used for?

Answer 44

Drug delivery systems, lubricants, catalysts, sports equipment.

Question 45

An example of a fullerene?

Answer 45

Carbon nanotubes.

Question 46

Properties of carbon nanotubes?

Answer 46

High electrical conductivity and are strong and flexible.

Question 47

How big are nanoparticles?

Answer 47

Between 1 and 100nm. ## Footnote Atom radius = 0.1nm.

Question 48

Advantages of nanoparticles?

Answer 48

High sa/v ratio so can react quickly. ## Footnote Make materials stronger and lighter, save lives, antibacterial properties, target specific cells.

Question 49

Disadvantages of nanoparticles?

Answer 49

Could be toxic, could enter bloodstream and cause harm, speed up reactions in unpredictable ways, physical handling is hard in liquid or dry forms.

Question 50

Uses of nanoparticles?

Answer 50

Sports equipment - tennis rackets, golf clubs, shoes. ## Footnote Clothing - silver nanoparticles added to socks to absorb smell. ## Footnote Sunscreens - offer protection and can be rubbed in so no white marks.

Question 51

What state is a substance at melting point or above?

Answer 51

Liquid.

Question 52

What state is a substance at boiling point or above?

Answer 52

Gas.