EL 1 

==Atoms containing-==

  • Positive proton with mass 1 and charge 1 found in nucleus
  • Neutral neutrons with mass 1 and charge 0 found in nucleus
  • Electrons with mass 0 and charge -1 found around nucleus
    Mass number = number of protons + number of neutrons in an atom
    Atomic number = number of protons in an atom

==The history of the atom==

  • Dalton- created the KS3 model of a partial
  • Thomson- found evidence for the electron, used the plum pudding model describing negative electrons embedded in a ball of positive charge
  • Rutherford- created the nuclear model describing negative electrons orbiting a positive nucleus
  • Moseley- in 1913 determined charges on nuclei allowing the periodic table to be arranged in order of atomic number instead of atomic mass
  • Bohr- in 1914 created a nuclear model with clearly defined orbits. The energy released when electrons fall from one shell to another is given out in an emissions spectrum
  • Chadwick- in 1932 Chadwick found evidence for partials in the nucleus with a mass but no charge to he discovered neutrons

==Isotopes=== atoms of the same element with different mass numbers. They have the same number of protons but different number of neutrons
==Mass spectroscopy=== samples are ionised to positive charged ions and these ions are separated to their mass to charge ratio (m/z) these separated ions are detected together with their relative abundance

  • In a mass spectroscopy graph, the y-axis shows the relative abundance of each ion and the x-axis shows the mass/charge ratio. Since the charge on the ions is mostly +1 it is most often assumed the x axis is simply the relative mass.
  • Sometimes the relative abundance in the graphs doesn’t add up to 100% so you need to make calculations to adjust the values so it does add up.

==Nuclear fusion === two lighter nuclei join to give a heavier nuclei (very high temperatures and pressure required). These condition are found in starts and are needed to overcome the repulsive forces that exist between two positively charged nuclei.

  • Two nuclei fuse and give off energy
  • This is how the first elements were created. Helium was created from hydrogen in starts through the nuclear fusion of 2 isotopes of hydrogen.