Outcome 2 Flashcards
what is a covalent bond?
non-metals held together by atoms sharing their electrons
list three ways molecules may be represented
- ball and stick
- space-filling
- computer generated
what is another name for a covalent compound?
a molecular compound
what is electronegativity?
the electron-attracting power of an atom
> left to right
what is a polar and non-polar bond?
polar- is formed between elements with different electronegativities
non-polar- is formed between elements with the same electronegativities
describe dispersion forces
occurs when the nuclei attract e- from neighbouring atoms
describe dipole-dipole attractions
occurs when the pos side of one molecule attracts the neg side of another molecule
describe hydrogen bonding
occurs between H molecules bonded with N, O or F
list 3 properties of molecular substances
- do not conduct electricity in solid, molten or dissolved forms
- generally polar compounds are soluble in polar solvents but is in soluble in non polar solvents (vise versa)
- are soft and easily scratched
use of NH3 , NO and O3
NH3- ammonia, cleaning agent
NO- nitrogen monoxide, pollutant from car exhaust
O3- ozone, in upper atmosphere
what are the formulas for sulfate, sulfite, nitrate, nitrite, phosphate and hydrogen carbonate
sulfate - SO4^2- sulfite - SO3^2- nitrate - NO3^- nitrite - NO2^- phosphate - PO4^3-
what is a covalent network lattice?
consists of countless atoms held together by covalent bonds forming a three dimensional network lattice
properties of a covalent network lattice
- very hard
- difficult to scratch
- have high melting and boiling points
- non conductors in solid and liquid states
- brittle/easy to shatter
what is an example of a covalent network lattice?
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
what is a covalent layer lattice?
consists of countless atoms held strongly together in planes by covalent bonds and forms two dimensional lattices held together by weak dispersion forces
what are examples of covalent layer lattices?
nanotubes, graphite, graphene and buckyballs
difference between saturated and unsaturated hydrocarbons
saturated- contains only single carbon-carbon bonds
unsaturated- contains double or triple carbon-carbon bonds
properties of hydrocarbons
- 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
what type of reactions do alkanes participate in?
combustion and substitution
what type of reactions do alkenes and alkynes undergo?
combustion and addition
what is a cyclic hydrocarbon?
is when the carbon backbone of a hydrocarbon can form a ring, have a prefix of cylco-, unsaturated, i.e. benzene
where does crude oil come from?
due to increased pressure and temperature over a long period of time on the decay of dead organisms petroleum is formed
what is cracking?
excess larger hydrocarbons are broken into smaller onces
what is a thermoplastic?
are plastics that have been repeatedly melted, reshaped and hardened by cooling, are malleable and can be recycled
