2 atomic structure

an atom

equal numbers of protons and electrons

1

1

1/2000

+1

0

-1

equal to the number of protons and neutrons in the nucelus

equal to the number of proton in the nucleus and to the number of electrons in the atom. defines the element

atoms have no charge so it should be 0, but by losing or gaining electrons they can gain a positive or negative charge

atoms that contain the same number of protons but different numbers of neutrons

chemical properties are related to number of electrons so isotopes of the same element have identical chemical properties. since their mass is different, the physical properties like density and boiling point are different

isotope A and isotope B (A abundance x A mass) + (B abundance x B mass) —————————————————————————– 100

using a mass spectrometer

a vaporized sample is injected into the instrument. atoms of the element are bombarded with a steam of high energy electrons in the ionization chamber. in practice the instrument is set so that only ions with a single positive charge are formed. the resulting unipositive ions pass through holes in parallel plates under the influence of an electric field where they are accelerated. the ions are then deflected by an external magnetic field.

mass of the ion and its charge. the smaller the mass and higher the charge the greater the deflection. ions with a particular mass/charge ratio are then recorded on a detector which measures both the mass and the relative amounts of all the ions present.

gamma alpha beta

highly penetrating

stopped by a few cm of air

stopped by a thin sheet of aliminium

nuclear power generation, the sterilization of surgical instruments in hospitals, crime dtection, finding cracks and stresses in food.

14 C 6

131 I 53