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Chemistry paper 1 AQA GCSE triple > Atomic structure > Flashcards

Atomic structure Flashcards

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1
Q

What is an atom

A

the smallest part of an element that can exist

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2
Q

what is an element

A

substance made up of only one type of atom

there are about 100 different elements in the periodic table

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3
Q

what are the columns in the periodic table called

A

groups

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4
Q

what are the rows in the periodic table called

A

periods

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5
Q

what are compounds

A

compounds are made up of two or more different elements combined together in fixed proportions
compounds can have different properties from the elements they are made from
compounds can only be separated into elements by chemical reactions

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6
Q

what are mixtures

A

mixtures consist of two or more elements or compounds not chemically combined together
the chemical properties of each substance in the mixture are unchanged

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7
Q

how can mixtures be separated

A 
by physical separation techniques 
filtration
-distillation
-chromatography
-fractional distillation
-crystalisation
physcial processes do not involve chemical reactions
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8
Q

name physical separation techniques

A
  • simple distillation
  • fractional distillation
  • crystalisation
  • filtration
  • chromatography
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9
Q

describe simple distillation

A

distillation is used to separate a soluble solid dissolved in a liquid ( usually water )
explanation-liquid boils off and condenses in the condenser. the thermometer will read the boiling point of the pure liquid

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10
Q

describe crystallisation

A

crystallisation is used to separate a soluble solid from a liquid.
to separate a soluble solid from a non flammable liquid we use evaporation. if we want to create hydrated crystals then we do not evaporate all the water from the mixture.
evaporating basin is large and shallow to increase surface area for quicker evaporation.

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11
Q

describe fractional distillation

A

used to separate soluble liquids with different boiling points.
fractionating column has a temperature gradient- cooler at the top and hotter at the bottom.
when a mixture of soluble liquids is heated all the liquids are evaporated. the liquid with the lowest boiling point froms the greatest percentage of vapour. As the vapour moves up the fractionating column, it becomes more rich with component that has lowest boiling point. this is because it condenses and evaporates as it moves up the column. a thermometer measures the temperature of the fractions before they condense. The liquid with the lowest boiling point is the first fraction collected.

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12
Q

describe filtration

A

filtration is used to separate insoluble solids suspended in a liquid.
the insoluble solid gets caught in the filter paper, because the particles are too big to fit through the holes in the paper. the filtrate is the substance that comes through the filter paper.

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13
Q

describe chromatography

A

chromatography is used to separate a mixture of soluble substances.
it is an example of a physical separation technique because no new substances are made and it does not involve chemical reactions. paper chromatography allows us to separate different substances based on their solubilities.
paper- stationary phase
solvent- mobile phase
each chemical in the mixture is attracted to the stationary phase to a different extent chemicals that move further up the paper are weakly attracted to the stationary phase than other chemicals.
pure substances will only produce a single spot in all solvents.
rf value= distance travelled by solute/ distance travelled by solvent

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14
Q

what did people think atoms were before the discovery of electrons

A

atoms were thought to be tiny spheres that could not be divided

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15
Q

Plum pudding model jj thompson

A
  • discovery of electron led to plum pudding model

- the pum pudding model suggested atom was a positive ball of charge with electrons embedded in it.

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16
Q

nucleur model ernest rutherford

A

formed from the results of rutherford’s alpha scattering experiment.
positively charged alpha particles were shot through gold foil.
- most of the alpha particles passed straight through the gold foil without changing direction which suggests atom is mainly empty space
-sometimes the alpha particles were deflected changed direction= centre of the atom must be positively charged atoms, that come close to this are repelled and change direction
-sometimes alpha particles bounced straight back towards the source= mass of an atom is concentrated in its nucleus. centre of atom creates great deal of mass most of the mass is concentrated in the nucleus.

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17
Q

Bohr model

A

Neils bohr adapted by the nucleur model by suggesting that electrons orbit the nucleus at specific distances. the orbits are now known as energy levels.
Bohrs calculations agreed with his experimental observations.

18
Q

discovery of protons

A

later experiments led to idea that positive charge of any nucleus could be subdivided into a whole number of sub particles- each particle has same amount of positive charge. these positively charged particles- protons

19
Q

James Chadwick- discovery of neutrons

A

explains existence of isotopes
isotopes- atoms of the same element with the same number of protons but different number of neutrons. neutrons have no overall charge

20
Q

structure of an atom

A

atoms have a small central nucleus made up of protons and neutrons.
atoms have no overall electrical charge- same number of electrons as number of protons charges cancel out
atoms are really small, size of radius is 1x10 -10 m
radius of nucleus 1x10-14m
most of the mass of the atom is concentrated in its nucleus.
mass number- total number of neautrons+total number of protons

21
Q

particle relative mass relative charge

A

particle- proton, electron , neutron
relative mass- proton= 1 neutron=1 electron= very small
relative charge= proton-+1 electron=-1 neutron=0

22
Q

relative charge meaning

A

charge of one particle compared to charge of another particle

23
Q

isotopes

A

atoms of the element that have the same number of protons but different number of neutrons. isotopes of an element have the same chemical properties because they have the same electronic structure

24
Q

what is the relative atomic mass of an element

A

relative atomic mass of an element is the average of masses of each isotope, taking into account the abundance of each isotope.
RAM= (mass number x abundance) / 100 percent

25
Q

periods and groups

A

elements in the same period have the same number of energy levels.
elements in the same group have the same number of electrons in their outer energy level and this gives them similar chemical properties

26
Q

group 0 elements

A

elements in group 0 are called nobel gases they are unreactive because they have a full outer energy level. ( stable arrangement of electrons)

27
Q

Modern periodic table

A

elements are arranged in increasing atomic number, so that elements with similar chemical properties are in the same group.
-atomic number gives number of protons or
electrons
o Elements in the same group have the same
number of electrons in their highest occupied
energy level (outer shell). (This explains
similar reactivity)
o Elements in the same period have the same
number of shells
o As you go down a group the number of shells
increases.

28
Q

Early periodic table

A

scientists grouped the elements in order of atomic weight.
early periodic tables were incomplete and some elements were placed in inappropriate groups- if strict order of atomic weights was followed
the discovery of istopes made it possible to explain why atomic weight ordering was not always correct.

29
Q

why is it called the periodic table

A

because similar properties occur at regular intervals

30
Q

Mendeleev

A

overcome some problems by leaving gaps for undsicovered elements and changed the order based on atomic weights in some places. mendeleev predicted properties for undiscovered elements and these matched his predictions

31
Q

Metals and non metals

A

elements that react to form positive ions are metals.

32
Q

Noble gases

A

elements in group 0 are unreactive because they have a stable arrangement of electrons. all the noble gases have 8 electrons in their outer energy level except helium which only has two electrons in its outer energy level.]the boiling points of the noble gases increase with increasing relative atomic mass.
helium, neon, argon, krypton, xenon,radon

33
Q

reaction of group 1 metals and water

A

group 1 metals react with water releasing hydrogen and forming hydroxides whihc dissolve in water to give alkaline solutions.
why are group 1 metals known as alkali metals= they react with water releasing hydrogen and forming hydroxides which dissolve in water to give alkaline solutions.
they react vigorously with water fizzing, and moving around surface of water.

34
Q

group 1 metals alkali metals- lithium, sodium, potassium, rubidium, caesium and francium

A

have similar chemical properties as they all have one electron in their outer energy level
have low densities first three li, na, k are less dense than water.
are stored under oil to prevent them from reacting with oxygen or water.
they react with non metals to form ionic compounds which are white colourless and can be dissolved in water
have relatively low melting and boiling points and melting point decreases as you go down the group

35
Q

why does group 1 metal reactivity increase going down the group

A

the reactivity increases as you go down the group because the number of energy levels increases, the atom gets larger and there is more shielding between the outer electron and the nucleus. weaker electrostatic force of attraction between negatively charged outer electron and positively charged nucleus, so electron is lost more easily.

36
Q

halogens group 7 flourine, chlorine, bromine. iodine, astatine

A

all have 7 electrons in their outer energy level.
have coloured molecules
are diatomic
form ionic salts with metals, chlorides, bromides, iodides
form small covalent molecules with other non metals.

37
Q

trends in group 7

A

boiling and melting points increase due to intermolecular forces
reactivity decreases, harder to gain an electron.
melting and boiling point increase as molecules become larger intermolecular forces become stronger and more energy is needed to overcome these forces.

38
Q

why reactivity decreases

A

the atom gets bigger, number of energy levels increases weaker electrostatic force of attraction between valence electron and positively charged nucelus so harder to gain an electron.

39
Q

halogen displacement reactions

A

a more reactive halogen can displace a less reactive halogen from an aqeaous solution of its salt

40
Q

transition metals

A 
central block
can form ions with different charges 
can from coloured compounds
can be used as catalysts.
have higher melting points
have higher densities 
stronger 
harder
less reactive than do not react as vigorously with water or oxygen.
41
Q

what did neutrons explain the existence of

A

isotopes

42
Q

what were niels bohr’s calculations supported by

A

his experimental observations

Chemistry paper 1 AQA GCSE triple (2 decks)

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