Atoms - key concepts
- Created by: Abigail Laverack
- Created on: 05-12-10 18:26
Protons have a mass of 1 annd a charge of +1
Electrons have a negligable mass and a charge of -1
Neutrons have a mass of 1 and a charge of 0
Mass number = Protons + Neutrons
Atomic number = Protons
Number of electrons = Number of Protons
Protons and neutrons are contained in the nucleus
Electrons are in shells around the nucleus
Isotopes are atoms with the same atomic number but a different mass number
Average atomic mass = average mass of 1 mole of an element / 1/12 mass of an atom of Carbon 12
Mass Spectrometry - a technique used to analyse atoms and molecules according to their masses. It is used to detect and measure the relative abundances of isotopes
Ionisation - an e- gun fires a beam of high energy e- at a vapourised sample knocking off e- so the atoms or molecules become mostly positive ions with a +1 charge
X(g) + e- ---> X+(g) + 2e-
Acceleration - charged plates produce an electric field which attracts positive ions causing them to accelerate down a tube. Holes in the plates allow some ions to pass through forming a beam of positive ions
Deflection - a magnetic field at bend in the tube deflects the ions of a specific mass/charge ratio (m/z) will hit the detector at the end of the tube and produce an output to a recorder. Heavier ions need a strong…
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