chemistry paper 1 Flashcards
why do elements in the same group act similar?
they have the same number of outer electrons
what is the attraction between atoms that have the opposite charge?
electrostatic attraction
what is a positively charged ion and a negatively charged ion called?
positive - cation
negative - anion
define element
a substance made up of atoms that all have the same number of protons in the nucleus
define compound
substances formed from two or more elements, the atoms of each are in fixed proportions throughout the compound and they’re held together by chemical bonds
define mixture
substances formed from two or more elements where there are no chemical bonds between the atoms
how does concentration impact equilibrium?
forward reaction slows down as the reactants react, backwards reaction speeds up
what happens at equilibrium?
both reactions are still happening, no overall effect
when can equilibrium occur?
in a closed system, nothing can get in or out
how is the reactivity series ordered?
how easily they lose electrons to form positive ions
acid + metal = ???
salt + hydrogen
metal + water = ???
metal hydroxide + hydrogen
how reactive do metals need to be to react with water?
very - high up reactivity series
define oxidation
gain of oxygen, loss of electrons
define reduction
gain of electrons, loss of oxygen
which metals can be extracted by reduction with carbon?
metals lower than carbon on the reactivity series
how do you extract metals higher than carbon on the reactivity series?
electrolysis
what are the components needed in electrolysis?
electrolyte - a molten or dissolved ionic compound
electrode - metals where the ions move toward
where do the positive and negative ions go during electrolysis?
positive - cathode to be reduced
negative - anode to be oxidised
half equations of aluminium oxide
Al3+ + 3e- –> Al
2O2- –> O2 + 4e-
what does the atom economy tell you?
the % of reactants forming useful products
what did bohr propose?
electrons orbit the nucleus in fixed positions
what did jj thomson suggest?
the plum pudding model. stoke are a ball of positive charge with electrons stuck in
what did rutherford prove?
he proved the plum pudding model was wrong by firing alpha particles at a sheet of gold, they passed through showing the atom has a nucleus
how is % mass calculated?
RAM x No of atoms / RFM
x 100
how do you calculate moles
mass / RFM
what is a limiting reactant
the reactant used up in a reaction
what is percentage yield
a comparison between actual and theoretical yield
how is percentage yield calculated
mass of products made / theoretical mass
x 100
what does one mole of any gas occupy
24dm3 at 20 oC
how do you work out volume of a gas
mass / RFM x 24
how are metals lower then carbon on the reactivity series extracted
using carbon
