Atoms and stuff

Edexcel chemistry

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1.5 Summary
A substance that cannot be broken down into two or more different substances
Smallest uncharged particle of an element
Made up of protons, neutrons and electrons
Mass of 1
Charge of +1
Found in nucleus of an atom
Mass of 1
No charge
Found in nucleus of an atom
Mass of 1/2000
Charge of -1
Found in shells surrounding the nucleus of an atom
Substance made of two or more elements

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Smallest particle in which a substance usually exists
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
Rutherford's experiment
Gold foil experiment using negatively charged beta radiation
Showed that:
Atoms made mostly of nothing
Most of the mass of an atom is concentrated in a tiny nucleus
The nucleus is positive
Rutherford's model of atom replaced the plum…read more

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Different number of neutrons
Identical properties because the number of electrons stays the same
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 à no ions (noble gases)
Transition elements à roman numerals show number of charge
Charges of radiation
Alpha radiation à positively charged
Beta radiation à negatively charged
Molecular ions
Ammonium à NH4+
Hydroxide à OH-…read more

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Molecular ions with a negative charge that contain oxygen
Names usually end in ­ite or ­ate.…read more

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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 as the parent or molecular ion
Analysis of urine samples
Pharmaceutical research
Radioactive dating
Space research
Studies of solar wind
Electron shells
Effectively limitless number of shells
Further away a shell is,…read more

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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
Difference in energy levels between sub-shells is between 1s and 2s
Regions of the periodic table
S-block elements have the outermost electron in the S sub-shell à groups 1 and 2
P-block elements have the outermost electron in the P sub-shell…read more

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Total number of shells = period number
Quantum mechanics
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 of a wave
Frequency à number of complete waves produced every second
Velocity = frequency x wavelength
Spectrum of light
Caused by different frequencies of waves
Spectrum = rainbow colours
Red à lowest frequency
Violet…read more

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Visible light
Gamma rays
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
Emission spectrum
Shows frequencies of light emitted by a source
Line spectra à the coloured lines on the emission spectrum
Absorption spectrum
Shows the frequencies of light that have been absorbed
Faunhoffer lines à black lines on the absorption spectrum
Red shift à the…read more

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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
Inner shells cancel out positive charge of
nucleus, reducing its effect on outer shells
Largest effect of shielding from full shells
The more shells, the larger the effect of shielding
Electron affinities
Opposite of ionisation energy
1st electron…read more

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