Topic 2- Bonding, structure and the properties of matter

Question 1

What is ionic bonding?

Answer 1

Ionic bonding is the electrostatic attraction between positive and negative ions.
It is a relatively strong attraction

Question 2

How are ionic compound held together?

Answer 2

-They are held together in giant lattice
-Its a regular structure that extends in all directions in a substance
-Electrostatic attraction between positive and negative ions holds the structure together

Question 3

State the properties of ionic substances

Answer 3

High melting and boiling points ( strong electrostatic force between oppositely charged ions)
Do not conduct electricity when solid (ions in fixed positions)
Conduct when molten or dissolved in water - ions are free to move

Question 4

What is important when working out a formula of an ionic compound

Answer 4

ionic compounds are electrically neutral, i.e positive and negative changes balance each other.

Question 5

How are ionic compounds formed?

Answer 5

Reaction of a metal with a non-metal
electron transfer occurs- metal gives away its outer shell electrons to non-metal

Question 6

What is a covalent bond?

Answer 6

covalent bond is a shared pair of electrons between two atoms.

Question 7

Describe the structure and properties of simple molecular covalent substances

Answer 7

Do not conduct electricity (no ions)
small molecules
weak intermolecular forces
low melting and boiling points

Question 8

How do intermolecular forces change as the mass/size of the molecule increases?

Answer 8

they increase. that cause melting/boiling points to increase as well (more energy needed to overcome these forces)

Question 9

What are polymers? What are thermosoftening polymers?

Answer 9

polymers are very large molecules with atoms linked by covalent bonds

thermosoftening polymers- special type of polymers; they melt/soften when heated. There are no bonds between polymer chains. strong intermolecular forces ensure that the structure is solid at room temperature. these forces are overcome with heating - polymer melts

Question 10

What are giant covalent substances? give examples

Answer 10

-solids, atoms covalently bonded together in a giant lattice
high melting/boiling - strong covalent bonds
mostly don’t conduct electricity (no delocalised electron)
-diamond, graphite, silicon dioxide

Question 11

Describe and the properties of diamond

Answer 11

-four, strong covalent bonds for each carbon atom
-very hard (strong bonds)
-very high melting point (strong bonds)
-doesn’t conduct (no delocalised electron)

Question 12

Describe and the properties of graphite

Answer 12

three covalent bonds for each carbon atom
layers of hexagonal rings
high melting point
layers free to slide as weak intermolecular forces between layers
soft, can be used as a lubricant
-conduct thermal and electricity due tone delocalised electron per each carbon atom

Question 13

Describe and the properties of fullerenes

Answer 13

hollow shaped molecules
based on hexagonal rings but may have 5/7 carbon rings
C60 has a spherical shape, simple molecular structure

Question 14

Describe and the properties of nanotubes

Answer 14

cylindrical fullerene with high length to diameter ration
high tensile strength (strong bonds)
Conductivity (delocalised electrons)

Question 15

Describe and the properties of graphene

Answer 15

a single layer of graphite

Question 16

What is metallic bonding?

Answer 16

forces of attraction between delocalised electrons and nuclei of metal ions

Question 17

describe properties of metals

Answer 17

high melting/boiling points
strong forces of attraction
good conductors of heat and electricity
malleable, soft

Question 18

What are alloys? why are they harder than pure metals?

Answer 18

mixtures of metal with other elements, usually metals
different sizes of atoms distorts the layers, so they can slide over each other, therefore alloys are harder than pure metals

Question 19

What are the limitations of the simple model?

Answer 19

There are no forces between spheres and atoms, molecules and ions are solid spheres - this is not true

Question 20

What does the amount of energy needed to change state from solid to liquid or liquid to gas depend on?

Answer 20

the strength of the forces between the particles of the substance. the nature of the particles involved depends on the type of bonding and the structure of the substance. the stronger the forces between the particles the higher the melting point and boiling point of the substance.

Question 21

A pure substance will melt or boil at…? What about the mixture?

Answer 21

A fixed temperature
A mixture will melt over a range of temperatures

Question 22

What are the three states of matter?

Answer 22

solid, liquid and gas

Question 23

What is nanoscience?

Answer 23

science that studies particles that are 1-100nm in size

Question 24

state the uses of nanoparticles

Answer 24

medicine (drug delivery systems)
electronics
deodorants
sun creams (better skin coverage and more effective protection against cell damage)

Question 25

What are fine and coarse particles?

Answer 25

fine particles (soot), 100-2500nm diameter
coarse particles (dust), 2500-10^5 nm diameter

Question 26

Why do nanoparticles have different properties to those for the same material in bulk?

Answer 26

high surface are to volume ratio