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AS Unit 1 Foundation Chemistry
Atomic Structure
History of the atom ­ constituent particles
~ fifth century BC Empedocles ­ a Greek philosopher proposed Air, Earth, Fire, and Water ­
and that all matter is made up of only these four components in variable proportions
Democritus of Abdera (460BC ­ 370BC) ­ postulated that there must come a point where matter
can no longer be subdivided ­ Leucippus used the term atomos (Greek word meaning
"indivisible") to describe the smallest portion of matter i.e.…read more

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AS Unit 1 Foundation Chemistry
http://www.youtube.com/watch?v=BhWgv0STLZs&feature=related
http://wwwoutreach.phy.cam.ac.uk/camphy/nucleus/nucleus1_1.htm
1932 ­ Chadwick ­ discovered the neutron
http://wwwoutreach.phy.cam.ac.uk/camphy/neutron/neutron5_1.…read more

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AS Unit 1 Foundation Chemistry
Atomic Particles
location relative mass relative charge
Proton nucleus 1 +1
Neutron nucleus 1 0
electron shells around nucleus 1
relative (to a proton) charge and mass are used since the actual individual values are tiny
proton (atomic) number (Z) Z = number of protons (unique to each element)
(hence is also the number of e as atoms are neutral)
nucleon (mass) number (A) A = (protons + neutrons)
A and Z can be used to determine the number of…read more

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AS Unit 1 Foundation Chemistry
Summary Questions Page 9 1 3
AS Chemistry (NELSON THORNES) AQA 4 ­ 5, 8 9
Chemguide (Web) Atomic number, mass spectra
5
12/12/2010…read more

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AS Unit 1 Foundation Chemistry
Relative Isotopic Mass
relative isotopic mass: mass of an atom of a particular isotope relative to of
the mass of a single atom of carbon12 (12C)
note how this differs from mass number
Mass Spectrometry
this provides us with two vital pieces of information about an atom of a given element
what is its MASS?
what is its RELATIVE abundance?
(as you will also later see we can
find out about molecules as well)
how a mass spectrometer works:
vaporisation…read more

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AS Unit 1 Foundation Chemistry
you must be able to interpret simple mass spectra to determine the elements present from their relative isotopic mass and also their relative
abundance
the value of the relative isotopic mass can be read directly from the m/z value of a given peak on the spectra from a mass
spectrometer
relative abundance is reflected in the heights of the peaks
Life on Mars?
http://www.synapses.co.uk/science/martian.html
http://phoenix.lpl.arizona.edu/science_tega.php
http://www.astrobio.net/news/modules.…read more

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AS Unit 1 Foundation Chemistry
Relative Atomic Mass (Ar)
relative atomic mass (Ar) weighted average of isotopic masses of atoms of an element
relative to of the mass of a single atom of carbon12 (12C)
(Ar ions Ar atoms since electrons have negligible mass)
the `weighted average' reflects the relative proportion of each isotope and is indicated by the relative heights of the peaks on the mass spectra
calculating Ar from isotopic mass and isotopic abundance (limited to mononuclear (+1) ions so don't worry about…read more

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AS Unit 1 Foundation Chemistry
Electronic Configuration
Energy Levels and Shells
1913 Bohr proposed a `solar system' model based on electron shells ­ in effect the GCSE model
1926 ­ Schrödinger ­ put forward a mathematical equation that described the electron as a wave effectively creating the science of quantum
mechanics
(the history of the above is interesting ­ there were a lot of bitter rivalries)
review simple (GCSE) energy level diagram (n = principal quantum number: 1, 2, 3..…read more

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AS Unit 1 Foundation Chemistry
these sub shells each have a discrete energy level (i.e. same value) in an isolated atom (this will only be studied further when you do transition
metals in Y13, however, it wont do you any harm to get to grips with orbital hybridisation if you desire a higher level of understanding)
each sublevel consists of electron orbital's (region of space in which the electron spends most of its time).
for more details on how the theory developed see:
http://en.wikipedia.…read more

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