AS Chemistry - Atomic Structure


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Define Mass Number It tells you the total number of protons and neutrons in the nucleus
Define 'Atomic Number' The number of protons in the nucleus (it identifies the element)
What are the Relative charges of the Subatomic particles Protons = +1 Neutrons = 0 Electrons = -1
Define the term isotope Isotopes are atoms of the same element with different numbers of neutrons
What are the Relative mass of the Subatomic particles Protons = 1 Neutrons = 1 Electrons = 0 (1/2000)
Who developed the 'nuclear' model of the atom? What evidence did they have for it? Rutherford developed the 'nuclear' model. His evidence for this model was that, when he fired alpha particles at a thin sheet of gold foil most of them based straight through, somthing that could not be explained by the old model
Describe the Bohr model of an atom(4 key points). How was it later refined? 1) Electrons can ONLY exist in fixed orbits(shells). 2) Each shell has a fixed energy. 3) When an electron moves between shells electromagnetic radiation is emitted/absorbed. 4) Because shell energy is fixed, radiation has fixed frequency. This was refined to include sub shells
What does 'relative atomic mass(Ar)' mean? 'Relative atomic mass(Ar)' is the average mass of an atom of an element on a scale where an atom of carbon-12 is 12
What does 'relative isotopic mass' mean? 'Relative isotopic mass' is the mass of an atom of an isotope on a scale where an atom of carbon-12 is 12
What is the difference between 'relative molecular mass' and 'relative formula mass'? 'relative formula mass' is used for compounds that are ionic or giant covalent
How does a mass spectrometer work (5 key points)? 1. Vaporisation 2. Ionisation 3. Acceleration 4. Deflection 5. Detection
What is order of the subshells, from 1s up to 4p? 1s 2s 2p 3s 3p 4s 3d 4p
How many electrons can occupy the following shells: s, p, d? s = 2 p = 6 d = 10
Which groups of the periodic table tend to gain electrons to form negative ions? groups 5, 6 and 7
Define the first ionisation energy The first ionisation energy is the energy needed to remove 1 mole of electrons from one mole of atoms in the gaseous state.
What are the three main factors that affect ionisation energies? Nuclear Charge, Distance from Nucleus, Shielding