2nd shell 8
3rd shell 8
Atomic number = number of protons or electrons
Mass number = number of protons + neutrons
Group number = number of valence/outermost electrons
Period number = number of electron shells
Ionic bonding = atoms become stable when they reach octect rule/noble gas configuration
Metals & non metals
Metals = lose electrons to form + ions
Nonmetals = gain electrons to form – ions
Naming ionic compounds 1. Name metal 2. Name non metal using ‘ide’
Mg + I = magnesium iodide
Covalent bonding * Non metals only * Share electrons to form covalent bonds
Naming covalent compounds 1. name a non metal with lower group number first 2. use prefixes to show number or each type of atom 3. hydrocarbons name second non metal using ‘ide’
Law of conservation of law/matter
“ matter cannot be created/destroyed, it can only change form”
Carbon chemistry
Organic compounds * Living things that once lived contained carbon * Carbon = building blocks of living tissue
e.g glucose, lipids, carbs main elements in organic compounds = CHONPS
Inorganic compounds substances that a) do not contain carbon e.g H20 , O2 or b) are not or were not living e.g CO, CO2, CH4
SiCL4 = silicon tetrachloride
Compounds that only consist of carbon and hydrogen
Naming hydrocarbons
Alkane CnH2n – 2
Propane & butane gas in BBQ, gas cylinders, cigarette lighters
Alkene CnH2n
Plastics & plastic bags
Alkyne CnH2n + 2
Blow torches used in welding (3000 degrees Celsius)
Fractional distillation * Crude oil= hydrocarbons & other substances * Crude oil & natural gases = formed from remains of animals hundreds of years ago * Remains decomposed under layers of rock and water in the absence of oxygen * To extract oil & gas, pipes drilled down through the rocks * Is refined/separated by fractional distillation * Tall cooling towers, crude oil is fed into base of the tower and separated into compounds
Cracking
* During distillation, some components are still too log * Heated in presence of catalyst (Al or Si) and are broken down into smaller molecules
Alcohol
* Hydrogen atom of a hydrocarbon is replaced by an oH (hydroxyl) group, compound Is called an alcohol * oH group is known as functional group b/c affects properties of compound * Alcohols formed from alkanes = alkanols
Fermentation
* Ethanol is used in alcoholic drinks, petrol’s, scents, and flavorings, solvent to make glues and inks * Produced by fermentation of sugar in fruits vegetables or cereals * Yeast= catalyst used to speed up reaction Glucose ethanol+ carbon dioxide C6H12O6(aq) 2C2H5OH (aq) + 2CO2 (g)
Used making wine and bread
Combustion
Occurs when hydrocarbons react with oxygen from air a) complete combustion i) plenty of oxygen ii) products are CO2 and H2o iii) large amounts of heat released
e.g blue flame in Bunsen burner b) incomplete combustion i) lack of oxygen ii) products are C (soot), CO and H20 iii) small amount of heat is released
e.g yellow flame of Bunsen burners, exhausts from cars polymers * plastics are made from small molecules containing carbon atoms * these molecules are produced from fractional distillation of crude oil a) monomers small molecules e.g ethane b) polymers large molecules containing thousands of monomers linked together in a chain monomers = linked by covalent bonds can all be the same/ have some different molecules type of monomers affect properties of the polymer c)