C2

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