Atoms and molecules

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what does the atom consist of
a nucleus which has protons and neutrons and electrons arranged in shells
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what are the properties of protons, neutrons and electrons
proton and neutron have the sma mass electron mass is ineligible. proton has positive charge, electron has negative charge which balance and neutron has no charge
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what is the atomic number
this is the number of protons and this identifies the element as they are put in order of increasing atomic number every atom of the same element has the same number of protons
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what is an isotope
they are atoms of the same element with different numbers of neutrons and different masses but the same number of protons
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isotopes and chemical reactions do they react in the same way
isotopes of an element react in the same way as they have the same no. of protons and electrons and neutrons have no effect on reactions - there may be small difference in physical properties
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what is an ion
it is a charged atom with the number of electron different from the number of protons
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what is a positive ion called
a cation and are atoms wit fewer electrons that protons
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what are negative ions called
anions are atoms with more electrons than protons
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what is the relative isotopic mass
this is the mass of an isotope relative to 1/12th of the mass of atom of carbon-12
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what is the relative atomic mass
it is the weighted mean mass of an atom of an element relative to 1/12th of the mass of an atom of carbon-12
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what does this weighted mass take into account
the percentage abundance of each isotope and the relative isotopic mass of each isotope
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how is the percentage abundance of an isotope found experimentally
by using a mass spectrometer
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what is the basic principle of procedure with a mass spectrometer
sample placed on it
sample is vaporised the ionised to form + ions
ions are accelerated heavier ions move slow and hard to be deflected and ions separate
ions are detected with mass to charge ratio
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what is the mass to charge ration
m/z = relative mass of ion/relative charge on ion
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how do you guess the ion of an element of the periodic table
metal on the left lose electrons to form positive ions and you can use the group they are in and non metals gain electron to form negative ions
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what is a binary compound
contain two elements only
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what are polyatomic ions - examples
NH4+, OH-, NO3-.NO2-, HCO3-, CO3^2-, SO4^2-, Cr2O7^2-, PO4^3-
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what is avagadros constant
Na is 6.02 x 10^23 in each mole of carbon-12
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what is the equation moles
moles = mass / Mr
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what is the molecular formula
is the number of atoms of each element in a molecule
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what is the empirical formula
is the simples whole number ratio of atoms of each element in the compound
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how to calculate from hydrate salts
go over in the book or watch video
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what assumptions are made when working out the experimental formula from hydrate copper
all water has been lost, nor further decomposition has occurred
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how do you work out mole with volume and concetratio
mole = conc. x volume
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what is a standard solution
is a solution of known concentration prepared by dissolving exact mass of solute in a solvent making up the solution to an exact volume
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how do you calculate the mole from gas volumes
mole = V/24(dm3) / 24000 (cm3)
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what are the assumptions with the ideal gas equation
random motion
elastic collision
negligible size
no intermolecular forces
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what is the ideal gas equation
pV = nRT
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what is the units for the ideal gas equation components
p - Pa
V - m3
T - K
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what is the limiting reagent
the reactant that is not in excess will be completely used up first and stop the reaction
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what is the equation for atom economy
Mr of desired products / Mr of all products x 100
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what does a high atom economy tell us
large proportion of desired products and few unwanted products
important for sustainability
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what is an acid
releases hydrogen ions as protons H+ into solution
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what is the difference between a strong and weak acid
a strong acid completely dissociates into its ions whilst a weak acid only partially dissociates
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what is a base
it neutralises an acid to form a salt
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what is an alkali
is a base that dissolves in water releasing hydroxide ions
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what are neutralisation reactions of acids
acid + meal oxide
acid + metal hydroxide
acid + alkali
acid + metal carbonate
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what are titration used for
find the conc. of a solution
identification of unknown chemical
finding the purity of a substance
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how do you prepare a standard solution
weigh solid accurately
dissolve in a beak using less distilled water needed to fill the volumetric flask
transferred to volumetric flask traces rinsed with distilled water
the flask is filled to graduation line
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how do you prepare a standard solution (2)
if too much water is added it will be too dilute
finally slowly invert the volumetric flask to mix solution thoroughly if this step miss titration wont be consistent
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what indicators can you use
phenolphthalein - acid going to alkali it goes from colourless to pink and the other way around for base to acid
and methyl orange goes from red to yellow
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when do you stop the titration
when you have concordant results which are results that differ by 0.10 cm3
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calculations with titration
watch video
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Other cards in this set

Card 2

Front

what are the properties of protons, neutrons and electrons

Back

proton and neutron have the sma mass electron mass is ineligible. proton has positive charge, electron has negative charge which balance and neutron has no charge

Card 3

Front

what is the atomic number

Back

Preview of the front of card 3

Card 4

Front

what is an isotope

Back

Preview of the front of card 4

Card 5

Front

isotopes and chemical reactions do they react in the same way

Back

Preview of the front of card 5
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