C1 - atomic structure Flashcards
the periodic table is arranged by…
atomic/proton number
what never changes about an element?
number of protons
how did Mendeleev rearrange the periodic table?
he reversed the order of some elements so they fitted in groups of reactivity
why did Mendeleev leave gaps in the periodic table?
he realised some elements were still undiscovered
how was Mendeleev’s table arranged?
in order of protons, not mass
number of protons = ?
atomic number
number of neutrons = ?
mass number minus atomic number
number of electrons = ?
number of protons
how are electrons arranged?
in shells
how many electrons can the 4th shell hold?
2
what does the group number tell us about the electrons?
number of electrons an element has in the outer shell
where are protons and neutrons located?
in the nucleus
where are electrons located?
in shells orbiting the nucleus
describe the plum pudding model
ball of positive charge with negative electrons embedded throughout
what did Rutherford suggest about electrons to prove the nuclear model incorrect?
they orbit the nucleus
how did Bohr develop the nuclear model further?
he suggested electrons were in shells orbiting a nucleus of protons
name a similarity between the plum pudding model and the nuclear model
both have negative and positive charges
what did James Chadwick discover in 1932?
neutrons
describe the results from the alpha scattering experiment
a few particles deflected, most went straight through
what did the alpha scattering experiment prove?
there’s a small area of high positive charge called the nucleus
define isotopes
atoms of the same number of protons but different number of neutrons
describe the properties of alkali (group 1) metals
shiny when cut but darken quickly as they react with oxygen in the air, low density
how do alkali metals react with water?
by fizzing and the metal dissolving
what does the fizzing tell us about water reacting with alkali metals?
hydrogen gas is being made
alkali metals become more reactive as you…
go down the group
why are alkali metals more reactive going down the group?
outer shell gets further away from the positive attraction of the nucleus, so more easy to lose outer shell electron
what are group 0 gases also known as?
noble gases
describe the properties of noble gases
inert and exist as single atoms as they have full outer shells of electrons
the boiling point of noble gases increases as you…
go down the group
describe the properties of group 7 elements (halogens)
non-metals which consist of diatomic molecules
the melting/boiling point of halogens increase as you…
go down the group
as you go down the group, halogens become…
less reactive
why do halogens become less reactive down the group?
the outer electrons get further away from the attraction of the nucleus, so it’s harder to gain an electron
describe the properties of transition metals
high melting points, dense, strong and hard, less reactive with water and oxygen
compare group 1 metals with transition metals
lower melting points, less dense, more reactive with water and oxygen
many transition metals have ions with…
different charges
what type of compound do many transition metals form?
coloured compounds
transition metals are frequently used as…
catalysts such as iron in the Haber process
what does filtration separate?
an insoluble solid from a liquid using filter paper and a funnel
what does crystallisation separate?
solids from solutions
describe the process of crystallisation
heat solution until it becomes saturated, leave to cool and evaporate leaving behind dry crystals
what does simple distillation separate?
liquid from solution
describe the process of simple distillation
heat mixture of liquids, boil, condense vapour and collect in a separate container
what does fractional distillation separate?
liquids of different boiling points
describe the process of f. distillation
heat mixture of liquids, boil, vapour rises up fractionating column, condenses and is collected in separate container
why do you use a pencil to draw a line during paper chromatography?
pencil marks are insoluble, so won’t dissolve in solvent or rise up filter paper
