Studied by 7 people
What is a pure substance?
an element or compound that melts/boils at specific temperatures
What is relative formula mass?
relative atomic masses added together
What is empirical formula?
the simplest ratio of the numbers
What is a formulation?
something (a mixture) which has been created to be a useful product eg. medicines
What is filtration?
filtering a solution to leave you with a precipitate
What is crystallisation?
separating a salt from a solution by evaporating the water
What is simple distillation?
separating a pure liquid from a solution by heating the mixture at the specific boiling points
What is fractional distillation?
normally done with oil by heating the mixture at different mixtures and condensing the vapour produced
What is chromatography?
separates mixtures and uses mobile and stationary phases
What is paper chromatography?
the mobile phase is the solvent and the stationary phase is the paper
What is TLC (thin layer chromatography)?
the mobile phase is the solvent and the stationary phase is an inert substance on a non-reactive surface
what is the Rf value?
distance moved by substance ÷ distance moved by solvent
What is gas chromatography?
the stationary phase is the liquid and the mobile phase is the inert gas carrier
What is a metal?
a reactive element that creates positive ions
What is a non-metal?
a reactive element that creates negative ions
How is the periodic tables organised?
in order of atomic number and elements in the same group have the same amount of electrons
What is the chemical bonds in ionic compounds?
when a metal and non-metal bonds and is connected with high forces and giant ionic lattices
What is the chemical bonds in simple molecules?
when molecules are covalently bonded by sharing electrons are normally gases or liquids
What is the chemical bonds in giant covalent structures?
solids with high melting points
What is the chemical bonds in polymers?
are connected by string covalent bonds and intermolecular forces so is solid at room temperature
What is the chemical bonds in metals?
giant structures and shared delocalised electrons with high melting and boiling points
What is a covalent bond?
electrostatic attractions between shared electrons
What is an ionic bond?
electrostatic attractions between charged ions
What is metallic bond?
electrostatic attractions between positive metal ions and delocalised electrons
What do dot and cross diagrams represent?
forming of ionic compounds but cannot represent the 3D arrangements
What is the arrangements of electrons in shells?
2,8,8
What was Mendeleev’s arrangment?
in order of atomic mass but left some missing for undiscovered elements
What is the structure of diamond?
each carbon is then connected covalently to four other carbon
What is the structure of graphite?
graphite is soft as each carbon is bonded to three other carbon atoms and they are in layers which can slide
What is the structure of fullerene?
made up of rings of five to seven carbon atoms
What is the structure of graphene?
one layer of graphite
What is energy transfer?
to - boiling,melting
from - freezing,condensing
What is the relative strength of chemical bonds?
both covalent and ionic bonds are extremely strong
What is intermolecular forces?
are weak so have low melting and boiling points
How big are nano-particles?
1x10-7 m
What are the features of nano-particles?
high surface are to volume ratio
What are the risks of using nano-particles?
there are unkown dangers of how our cells react
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