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1.5 Summary
DEFINITIONS
Element
A substance that cannot be broken down into two or more different substances
Atom
Smallest uncharged particle of an element
Made up of protons, neutrons and electrons
Protons
Mass of 1
Charge of +1
Found in nucleus of an atom
Neutrons
Mass of 1
No charge…

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Molecule
Smallest particle in which a substance usually exists
Ion
Atom or group of atoms that has lost or gained electrons so it is charged
Positive ions = cations à attracted to cathode
Negative ions = anions à attracted to anode
MODEL OF ATOM
Rutherford's experiment
Gold foil experiment using…

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Different number of neutrons
Identical properties because the number of electrons stays the same
IONS
Charges of ions
Group 1 à +
Group 2 à 2+
Group 3 à 3+
Group 4 à no simple ions
Group 5 à 3-
Group 6 à 2-
Group 7 à -
Group 8…

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Oxyanions
Molecular ions with a negative charge that contain oxygen
Names usually end in ­ite or ­ate.
MASS
Standard mass
1/12th of the mass of one 12C atom
Relative isotopic mass
The mass of one atom of an isotope relative to 1/12th of the mass of one 12C atom
Almost…

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Detect build up of charge
Interpreting results of mass spectrometer
Results shown on computer screen as graph
Mass/charge on x-axis
Abundance on y-axis


Uses of a mass spectrometer
Finding the relative atomic mass (Ar)
Finding the relative molecular mass (Mr) à peak furthest to the right on the graph, known…

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Orbitals contain 2 electrons
S = 1 orbital
P = 3 orbitals
D = 5 orbitals
F = 7 orbitals
Orbitals gain one electron each in a sub-shell before gaining 2 because electrons are negatively charged so repel each other
Energy level shorthand
1s22s22p63s23p64s23d104p6
Difference in energy levels between sub-shells…

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Total number of shells = period number
QUANTUM MECHANICS
Quantum mechanics
Probabilities
Electrons can have the properties of waves or particles
Shape of sub-shells
Electromagnetic waves
Transverse à wiggley like water
Travel at the speed of light
Include visible light
Properties of waves
Wavelength à distance between two identical points…

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Visible light
UV
X-rays
Gamma rays
Photons
Unit of light
Energy of photon = Planch's constant (h) x frequency (f)
Light given out due to changes in energy levels à the bigger the change, the higher the frequency emitted
MEASURING LIGHT
Emission spectrum
Shows frequencies of light emitted by a…

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Increase going across periodic table
Nuclear charge increases
No change in shielding
Decrease going down the periodic table
Shielding increases
Outer electrons further from nucleus
Shielding makes up for increasing nuclear charge
Smallest ionisation energy à bottom left
Largest ionisation energy à top right
Shielding
Inner shells cancel out positive…

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