AS AQA chemistry atomic structure.

Megan Vann
Flashcards by Megan Vann, updated more than 1 year ago
Megan Vann
Created by Megan Vann over 6 years ago
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State the Relative charge and mass of electrons, protons and neutrons. Electron- RM is 0- RC is -1. Proton-RM is 1-RC is +1. Neutron-RM is 1-RC is 0.
what did Bohr's atomic structure model predict? That atoms and ions with Nobel gas electron arrangements should be stable.
name the people who came up with the different atomic structure models.(in order) john Dalton-solid spheres JJ Thompson-plum pudding model Rutherford-gold foil-nuclear model Bohr-electrons in shells and Nobel gasses are stable.
What is mass number? The total number of protons and neutrons in the nucleus.
what is atomic (proton) number? the number of protons in the nucleus.
what is an isotope? isotopes of an element are atoms with the same number of protons but different numbers of neutrons.
what four stages occur in mass spectrometry? 1) Ionisation 2) Acceleration 3) deflection 4) detection
what happens during ionisation in mass spec? The atoms of the element is bombarded with a stream of high energy electrons from an electron gun. An electron is knocked out of the atom to produce a positive ion. e- + X(g) ----> X(g)+ + 2e-
what happens during acceleration in mass spec? the positive ions are accelerated by an electric field and focussed into a beam by passing through slits.
what happens during deflection in mass spec? The fast moving beam of ions is deflected by a magnetic field.
what happens during detection in a mass spec? The ions hit a charged plate and a small current is produced. the size of the current is proportional to the number ( abundance) of the ions. electrons are transferred from the charged plate to the positive ions.
what does the y-axis show on a mass spectrum? it gives the abundance of ions. For an element the height of each peak gives the relative isotopic abundance.
What does the x-axis show on a mass spectrum? show the mass/charge ratio- relative isotopic mass.
How do you calculate relative atomic mass from a mass spectrum? times each relative isotopic mass ( x axis) by the isotopes relative abundance. divide this total by the total relative abundance ( y-axis, usually 100%)
what can mass spectrometry be used to identify? elements( as used in planetary space probes)
what can mass spectrometry be used to determine? relative molecular mass. ( peak furthest to right)
what are the names of the sub levels that electrons are arranged on? s, p and d
what is ionisation energy? the energy required for the following process: X(g) --> X(g)+ + e-
how do ionisation energies in group 2 give evidence for electron arrangement in sub-levels and levels? The ionisation energy decreases- easier to remove electron. If each element has an extra shell than the one before the extra inner shells will shield the outer electrons from the attraction to the nucleus. the extra shell will also mean the electrons are further away, making the attraction generally less.
How do ionisation energies in period 3 give evidence for electron arrangement in sub-levels and levels? The drop between groups 2 and three shows sub-shell structure. Mg--->Al Al has a lower IE than Mg( doesn't follow trend) because outer most electron is on a 3p orbital rather than a 3s which has a slightly higher energy + extra shielding+ on average further away from nucleus.
Define relative atomic mass (Ar) (average mass of one atom of an element) ___________________________ (1/12 x mass of one atom of C12)
Define relative molecular mass (Mr) average mass of one molecule ___________________________ (1/12 x mass of one atom of C12)
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