chemistry

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  • Created by: 16chlhan
  • Created on: 28-09-20 19:59
what are substances made of ?
atoms
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how many atoms are elements made of?
one type of atom
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what are compounds ?
two or more elements combined together
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what do chemical equations show us ?
the reactants and products
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what are word equations used for?
they give the name of reactants and products only
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whats the word equation for the reaction between hydrogen and oxygen to produce water ?
hydrogen + oxygen - water
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what happens to the atoms in chemical reactions?
they get rearranged
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what's the Law of conservation of mass?
it states that no atoms are lost or made during a chemical reaction. Therefor, the mass of products is equal t mass of reactants
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what is a mixture ?
two or more substances that aren't chemically combined
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what are the physical ways to separate mixtures
filtration, crystallisation, distillation
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give example of each physical process...
filtration-sand can be separated from salt, crystallisation- salt from salt solution, distillation- sea water distilled to obtain usable water
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what is fractional distillation?
it is a way to separate mixtures of miscible liquids using fractional column
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give an example of fractional distillation?
ethanol and water
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how does this work?
they have different boiling points. the liquid with the lowest boiling point is collected first
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name a method to separate food dyes?
paper chromatography
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who were the first to have ideas about atoms?
The Greeks
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who suggested that the atoms were tiny hard spheres that could divide or split?
Dalton in the early 1800's
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who discovered the tiny negatively charged particles and invented the 'plum pudding' model?
thomson
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what did the 'pum pudding' mdelsuggest?
negative electrons were embedded in positive charge
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who was experimenting with alpha particles ?
Geiger and Marsden
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what did they do?
they fired alpha particles at a thin piece of gold foil and only a few repelled meaning there must be a tiny positive charge
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who proposed the 'nuclear model'?
Rutherford
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what was the 'nuclear model'?
electrons orbit around the nucleus and the nucleus contains positive electrons
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who disagreed with the nuclear model
Bohr. He suggested that electrons were orbiting the nucleus in shells and set at a distance from the nucleus.
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why did the model of the atom change over time?
scientists used the models as predictions and were suprised when they found new evidence which was different to the original model.
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who discovered the neutron?
Chadwick
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what is at the centre of the atom and what does it contain?
the nucleus is at the centre and it contains protons and neutrons
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what charge are electrons?
negatively
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what are the relative charges of the proton and electron?
proton = +1 electron= -1
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what is the atomic number?
proton number
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what is the *** number ?
is the total number of particles in the nucleus. so the number of protons + the number of neutrons
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what is the proton, neutron and electron number of fluorine?
protons = 9 electron = 9 ( proton and electron is the same) neutron = 19 - 9 = 10
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what is an ion?
it's a charged atom or group of atoms
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what happens to an atom which gains electrons?
they become a negative ion
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what happens to an atom which loses electrons?
they become positive ions
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what are isotopes?
when atoms of the same element have different numbers of neutrons
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what do the electrons on the shell closest to the nucleus do?
they control the available energy levels
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what does the electronic structure show?
it shows the number of electrons in each energy level.
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how many electrons are in the highest energy level of group 2 elements?
2 electrons
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what is the name of the elements in group 0?
Nobel gases
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why are 'noble gases' unreactive?
their atoms have a very stable arrangement of electrons. Apart from helium they all have eight electrons in their outer shell
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Other cards in this set

Card 2

Front

how many atoms are elements made of?

Back

one type of atom

Card 3

Front

what are compounds ?

Back

Preview of the front of card 3

Card 4

Front

what do chemical equations show us ?

Back

Preview of the front of card 4

Card 5

Front

what are word equations used for?

Back

Preview of the front of card 5
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