unit 2 - electrical conductivity

Question 1

what is an electrical current?

Answer 1

a flow of charged particles (e-, ions)

Question 2

what do conductors of electricity allow?

Answer 2

they allow an electrical current to flow through them

Question 3

what do non-conductors of electricity not allow?

Answer 3

they dont allow an electrical current to flow through them

Question 4

describe the experiment for finding out what elements conduct electricity.

Answer 4

connect a battery to a bulb then the bulb to an element, if the bulb glows when in contact with the element it is a conductor

Question 5

what elements are electrical conductors?

Answer 5

metal elements and carbon in the form of graphite

Question 6

what elements are not electrical conductors?

Answer 6

non-metals

Question 7

what do the atoms share in a covalent bond?

Answer 7

a pair of electrons

Question 8

why is there no conduction of electricity in a covalent bond?

Answer 8

because the electrons are not free to move around because the atoms share a pair of electrons

Question 9

why do non-metals not conduct electricity?

Answer 9

because they do not have charged particles which can move and therefore they do not conduct electricity

Question 10

what is the one electrical conductor that is a non-metal?

Answer 10

carbon in the form of graphite

Question 11

what does carbon in the form of graphite have?

Answer 11

a layered covalent network structure

Question 12

what does each carbon in the form of graphite atom use?

Answer 12

only 3 electrons for bonding, the remaining electron is delocalised over the whole structure

Question 13

why can carbon in the form of graphite conduct electricity?

Answer 13

because the electrons are free to move between the layers therefore the electrons can flow through it

Question 14

what compounds do not conduct electricity? and why?

Answer 14

-covalent compounds because the electrons in covalent compound are not free to move,

-ionic compounds do not conduct electricity in the solid state, however they conduct when dissolved in water or when molten

Question 15

why can ionic compounds only conduct electricity when dissolved in water or when molten?

Answer 15

because the lattice break and the ions become free to move

Question 16

what may covalent molecular substances which are insoluble in water dissolve in?

Answer 16

other solvents

Question 17

what does not dissolve?

Answer 17

covalent network substances

Question 18

what happens as covalent molecular substances dissolve?

Answer 18

the lattice structure breaks up allowing water molecules to surround the seperated ions

Question 19

what is a saturated solution?

Answer 19

it is a solution which has dissolved as much solute as it is capable of dissolving

Question 20

what do ionic compounds tend to be insoluble in?

Answer 20

covalent solvents, like ethanol

Question 21

if your writing out a word equation with the elements symbols do you need to show if they’re diatomic?

Answer 21

YES!!!

Question 22

what is the GFM?

Answer 22

the mass in grams of ONE MOLE of a substance

Question 23

what are the all the equations for m, n, gfm, calculations?

Answer 23

-(m=n x gfm)
-(n=m / gfm)
-(gfm=m / n)

Question 24

Explain the physical properties of ionic compounds:

1.melting point and boiling point
2.solubility (water molecules surround ions)
3.electrical conductivity

Answer 24

1. Ionic compounds have high melting and boiling points because strong ionic bonds must be broken in order to break down the lattice.
2. Tend to be soluble in water.
3. Ionic compounds conduct electricity only when molten or in solution, due to the breakdown of the lattice resulting in the ions being free to move.

Question 25

Explain the physical properties of covalent network compounds:

1.melting point and boiling point
2.solubility (water molecules surround ions)
3.electrical conductivity

Answer 25

1. Giant covalent network structures have very high melting and boiling points because the network of strong covalent bonds must be broken.
2. Covalent molecules tend to be insoluble in water but soluble in covalent type solvents.
3. Covalent molecules never conduct except carbon graphite.

Question 26

Explain the physical properties of discrete molecular covalent compounds:

1.melting point and boiling point
2.solubility (water molecules surround ions)
3.electrical conductivity

Answer 26

1. Covalent molecular substances have low melting and boiling points as only weak forces of attraction between molecules are being broken.
2. Covalent molecules tend to be insoluble in water but soluble in covalent type solvents.
3. Covalent molecules never conduct except carbon graphite.

Question 27

which diatomic element contains a double covalent bond?

Answer 27

Oxygen

Question 28

What elements do not form ions?

Answer 28

The noble gases

Question 29

What is the overlapping region between the two atoms called?

Answer 29

An orbital overlap