compounds Flashcards
chemical formulae
letters which represent the elements in the compound and numbers which tell us how many atoms of each element there are
example of chemical formulae
K2SO4
what are the elements with a 2 in their formula
-hydrogen H2
-nitrogen N2
-oxygen, O2
-fluorine, F2
-bromine, Br2
-chlorine, Cl2
-iodine, I2
what are compounds
they are substances which are made of two or more different types of atom that are chemically joined
what are the properties like in compounds
the compound has completely different properties to its constituent elements
Carbon dioxide
CO2 1 carbon, 2 oxygen
methane
CH4 1 carbon, 4 hydrogen
sulphur dioxide
SO2 1 sulphur, 2 oxygen
water
H2O 2 hydrogen, 1 oxygen
ions
is an atom/ molecule that has a different number of protons to electrons, so it has a different charge.
metal atom ions
need to lose electrons to gain full outer shells
non metal ions
need to gain electrons
hydrogen charge
+1
oxygen charge
-2
nitrogen charge
-3
fluorine charge
-1
relative molecule mass
it is a measure of the total mass of all the atoms in a molecule
what is relative molecule mass abbreviated to
RMM or M
how do you find the RMM
by adding all the Ar ( relative atomic mass) values in a molecule together
percentage composition?
the percentage by mass of an element in a compound
how do you work out percentage composition
% of element= Ar x number of atoms / RMM of compound
How are mixtures separated
filtration
evaporation
chromatography
distillation
distillation
used to separate mixtures of liquids that boil at different temperatures