revision 1 Flashcards
what is a compound?
A compound is formed when 2 or more elements join together.
what is an ionic bond?
A compound which is formed from a metal and a non-metal. The metal loses an electron to become positively charged and the non-metal gains this electron and becomes negatively charged.
what is a covalent bond?
A compound formed from non-metals. Each atom shares an electron with another atom.
what is an element?
A substance made up of only one type of atom.
what is limestone used for?
chemicals used in dyes,paints and medicines
houses and roads require limestone
acidity caused by acid rain in lakes can be neutralised with limestone.
also used in power station chimneys to neutralise sulphur dioxide = acid rain
why can quarrying limestone be bad?
changes the landscape- huge holes in ground
lots of noise and dust in quiet areas
destroys habitats of animals
waste materials = unsightly
limestone needs to be transported away = lorries= more pollution
advantages and disadvantages of limestone…
very quick and cheap
some types are more hard wearing than marble
fairly easy to cut
doesn’t rot and cannot be gnawed away by insects
fire resistant
doesn’t corrode
low tensile strength
very unattractive material
what is the difference between cement and mortar?
cement can be mixed with sand and water to make mortar. Mortar = stick bricks together
cement is powdered clay mixed with powdered limestone, heated in a kiln
benefits to economy of quarrying limestone…
brings money and jobs into the area = boost local economy= improvements in healthcare, education, roads
why can making stuff from limestone cause pollution? ( cement and mortar)
cement factories = lots of dust = breathing problems for some people
energy needed to produce cement = usually fossil fuels = pollution
what is a metal ore?
A metal ore is a rock that contains enough metal to make it worthwhile to extract the metal from it
how can metals be extracted?
from their ores chemically, by reduction with carbon or by electrolysis (splitting it up using electricity)
electrolysis can also be used to purify the extracted metal
what happens when an ore is reduced?
oxygen is removed
how are metals higher than carbon in the reactivity series extracted?
by electrolysis (splitting up with electricity) disadvantage = expensive
how are metals lower than carbon in the reactivity series extracted?
by reduction with carbon
