ATOMIC HISTORY & ISOTOPES

Thomson’s experiment involveda cathode ray tube with a gas at lowpressure. The gas flowed from the negative end to the positive end of the tube. Because the gas consisted of electrons, it was repelled by the negative end of the magnet and attracted by the positive end of the magnet showing that an electron is negatively charged

THOMSON’S MODEL IS CALLED THE PLUM PUDDING MODEL

Thomson explained that the model was like plums representing the electrons in pudding represented as protons

Rutherford’s Gold Foil experiment involved shooting positively charged alpha particles through a thin piece of gold foil. He expected the alpha particles to pass straight through or get struck in the positive part. Instead most alpha particles passed straight through but a few were deflected or bounced straight back. This lead to the conclusion that an atom is mostly empty space but has a very small positively charged center (nucleus)

ISOTOPES

ISOTOPES: Describe an isotope, compare the properties of the isotope of an element and deduce the symbol of an isotope given its mass number and atomic number. RELATIVE MASS (AVERAGE ATOMIC MASS): Calculate the non integer relative mass and abundance of isotopes from given data.