Outcome 2

Question 1

what is a covalent bond?

Answer 1

non-metals held together by atoms sharing their electrons

Question 2

list three ways molecules may be represented

Answer 2

1. ball and stick
2. space-filling
3. computer generated

Question 3

what is another name for a covalent compound?

Answer 3

a molecular compound

Question 4

what is electronegativity?

Answer 4

the electron-attracting power of an atom

> left to right

Question 5

what is a polar and non-polar bond?

Answer 5

polar- is formed between elements with different electronegativities
non-polar- is formed between elements with the same electronegativities

Question 6

describe dispersion forces

Answer 6

occurs when the nuclei attract e- from neighbouring atoms

Question 7

describe dipole-dipole attractions

Answer 7

occurs when the pos side of one molecule attracts the neg side of another molecule

Question 8

describe hydrogen bonding

Answer 8

occurs between H molecules bonded with N, O or F

Question 9

list 3 properties of molecular substances

Answer 9

1. do not conduct electricity in solid, molten or dissolved forms
2. generally polar compounds are soluble in polar solvents but is in soluble in non polar solvents (vise versa)
3. are soft and easily scratched

Question 10

use of NH3 , NO and O3

Answer 10

NH3- ammonia, cleaning agent
NO- nitrogen monoxide, pollutant from car exhaust
O3- ozone, in upper atmosphere

Question 11

what are the formulas for sulfate, sulfite, nitrate, nitrite, phosphate and hydrogen carbonate

Answer 11

sulfate - SO4^2-
sulfite - SO3^2-
nitrate - NO3^-
nitrite - NO2^-
phosphate - PO4^3-

Question 12

what is a covalent network lattice?

Answer 12

consists of countless atoms held together by covalent bonds forming a three dimensional network lattice

Question 13

properties of a covalent network lattice

Answer 13

• very hard
• difficult to scratch
• have high melting and boiling points
• non conductors in solid and liquid states
• brittle/easy to shatter

Question 14

what is an example of a covalent network lattice?

Answer 14

diamond - hardest known substance, made of strongly bonded carbon atoms, is in a three-dimensional tetrahedral lattice, is used as an abrasive for sawing, cutting and grinding hard substances

Question 15

what is a covalent layer lattice?

Answer 15

consists of countless atoms held strongly together in planes by covalent bonds and forms two dimensional lattices held together by weak dispersion forces

Question 16

what are examples of covalent layer lattices?

Answer 16

nanotubes, graphite, graphene and buckyballs

Question 17

difference between saturated and unsaturated hydrocarbons

Answer 17

saturated- contains only single carbon-carbon bonds

unsaturated- contains double or triple carbon-carbon bonds

Question 18

properties of hydrocarbons

Answer 18

• are generally insoluble and have no reaction with water
• more likely to be soluble in non-polar solvents
• boiling points increase with length of the molecule

Question 19

what type of reactions do alkanes participate in?

Answer 19

combustion and substitution

Question 20

what type of reactions do alkenes and alkynes undergo?

Answer 20

combustion and addition

Question 21

what is a cyclic hydrocarbon?

Answer 21

is when the carbon backbone of a hydrocarbon can form a ring, have a prefix of cylco-, unsaturated, i.e. benzene

Question 22

where does crude oil come from?

Answer 22

due to increased pressure and temperature over a long period of time on the decay of dead organisms petroleum is formed

Question 23

what is cracking?

Answer 23

excess larger hydrocarbons are broken into smaller onces

Question 24

what is a thermoplastic?

Answer 24

are plastics that have been repeatedly melted, reshaped and hardened by cooling, are malleable and can be recycled

Question 25

what is a thermosetting plastic

Answer 25

are plastics that char when heated, do not reshaped and cannot be recycled

Question 26

what is addition polymerisation?

Answer 26

is made from monomers with a double bond, where the reaction occurs at the double bonds and creates long chains called polymers