Giant Covakent Structures

Question 1

What type of bonds are present in giant covalent structures?

Answer 1

Strong covalent bonds

All atoms in giant covalent structures are bonded to each other by strong covalent bonds.

Question 2

What are the melting and boiling points of giant covalent structures like?

Answer 2

Very high

Lots of energy is needed to break the covalent bonds.

Question 3

Do giant covalent structures conduct electricity?

Answer 3

No

They generally don’t contain charged particles.

Question 4

Are giant covalent structures soluble in water?

Answer 4

No

Except for graphite and graphene.

Question 5

What is diamond made up of?

Answer 5

A network of carbon atoms

Each carbon atom forms four covalent bonds.

Question 6

Why does diamond have a high melting point?

Answer 6

Strong covalent bonds take lots of energy to break

The rigid lattice structure contributes to its hardness.

Question 7

What property of diamond makes it useful for cutting tools?

Answer 7

Hardness

Diamond is used to strengthen cutting tools like saw teeth and drill bits.

Question 8

How does graphite’s structure differ from diamond’s?

Answer 8

Each carbon atom forms three covalent bonds

Graphite creates sheets of carbon atoms arranged in hexagons.

Question 9

What makes graphite soft and slippery?

Answer 9

Weak forces between layers

There are no covalent bonds between the layers.

Question 10

Why does graphite conduct electricity?

Answer 10

Delocalised electrons

Each carbon atom has one free electron that can move.

Question 11

What is graphene?

Answer 11

One layer of graphite

It is a sheet of carbon atoms joined together in hexagons.

Question 12

What are fullerenes?

Answer 12

Molecules of carbon shaped like closed tubes or hollow balls

They can contain hexagons, pentagons, or heptagons.

Question 13

What is the molecular formula of Buckminsterfullerene?

Answer 13

C60

It forms a hollow sphere made up of 20 hexagons and 12 pentagons.

Question 14

What is a potential use of fullerenes?

Answer 14

To ‘cage’ other molecules

This could be used to deliver drugs directly to cells.

Question 15

What property of fullerenes makes them useful as catalysts?

Answer 15

Huge surface area

Individual catalyst molecules can be attached to fullerenes.

Question 16

What are nanotubes?

Answer 16

Tiny cylinders of graphene

They conduct electricity and have high tensile strength.

Question 17

What is a unique characteristic of nanotubes?

Answer 17

High tensile strength

They don’t break when stretched and can strengthen materials without adding much weight.

Question 18

Describe the structure and bonding of graphite.

Answer 18

Graphite consists of layers of carbon atoms arranged in hexagons, with weak forces between layers allowing them to slide over each other.

Question 20

What is a covalent bond?

Answer 20

A strong bond that forms when a pair of electrons is shared between two atoms.

Question 21

What are simple molecular substances made up of?

Answer 21

Molecules containing a few atoms joined by covalent bonds.

Question 22

What is the molecular formula for hydrogen chloride?

Answer 22

HCl

Question 23

How many electrons do hydrogen atoms need to complete their first shell?

Answer 23

One more electron.

Question 24

What forms when two hydrogen atoms share electrons?

Answer 24

A single covalent bond.

Question 25

What is the molecular formula for water?

Answer 25

H2O

Question 26

How many single covalent bonds are formed in a water molecule?

Answer 26

Two single covalent bonds.

Question 27

What does an oxygen atom need to complete its outer shell?

Answer 27

Two more electrons.

Question 28

What type of covalent bond do two oxygen atoms form in oxygen gas?

Answer 28

A double covalent bond. ## Footnote This type of bond occurs when more than one pair of electrons are shared between the atoms to attain a full outer shell

Question 29

What is the molecular formula for methane?

Answer 29

CH4

Question 30

How many covalent bonds can carbon form to fill its outer shell?

Answer 30

Four covalent bonds.

Question 31

What is the typical size of simple molecules?

Answer 31

Around 10^-10 m.

Question 32

What is the strength of the forces of attraction between simple molecular substances?

Answer 32

Very weak.

Question 33

What needs to be broken to melt or boil a simple molecular compound?

Answer 33

Intermolecular forces.

Question 34

What is the state of most molecular substances at room temperature?

Answer 34

Gases or liquids.

Question 35

How does the size of molecules affect their melting and boiling points?

Answer 35

As molecules get bigger, melting and boiling points increase due to stronger intermolecular forces.

Question 36

Do molecular compounds conduct electricity?

Answer 36

No, because they don't contain free electrons or ions.

Question 37

What are polymers made of?

Answer 37

Long chains of covalently bonded carbon atoms.

Question 38

What is a famous example of a polymer?

Answer 38

Poly(ethene).

Question 39

What are small molecules that join together to form polymers called?

Answer 39

Monomers.

Question 40

What is the term for the repeating unit in a polymer?

Answer 40

Repeat unit.

Question 41

Why is oxygen, O2, a gas at room temperature?

Answer 41

Due to weak intermolecular forces between other 02 molecules ## Footnote However there are strong covalent bonds between each individual paired oxygen atom

Question 42

Why doesn't nitrogen, N2, conduct electricity?

Answer 42

It doesn't contain free electrons.