Atomic Structure

• Proton relative mass is 1 and relative charge is +1
• Neutron has a relative mass of 1 and a relative charge of 0
• Electron relative mass is very small and relative charge is -1
• An isotope is the same number of protons but a different number of neutrons
• Compounds are substances formed from two or more elements, the atoms of each are in fixed proportions and held by chemical bonds
• History of the atom: Democritus, Dalton, Thompson, Rutherford, Bohr, Chadwick
• Dalton described atoms as solid spheres and said that different spheres made up the different elements
• Thompson found out atoms aren’t solid spheres and showed that atoms have negatively charged particles, electrons. He made the plum pudding model that showed the atom as a ball of positive charge with electrons stuck in it
• Rutherford showed that the plum pudding model was wrong through his alpha particle scattering experiment.
• Alkali metals form ionic compounds which are usually white solids that dissolve in water to form colorless solutions
• When alkali metals are put in water, they react vigorously to produce hydrogen gas and metal hydroxides and also give alkaline solutions
• When alkali metals react vigorously when heated in chlorine gas to form white metal chloride salts
• Alkali metals can react with oxygen to form a metal oxide
• Halogens are all non metals with colored vapors and exist in pairs:

  • Fluorine is a yellow gas
  • Chlorine is a dense green gas
  • Bromine is a red-brown volatile liquid
  • Iodine is a dark grey purple vapor
• Group 0 elements are all inert, colorless gases that are monatomic as they are single atoms not bonded to each other
• Newland‘s octaves: ordered elements where every 8th element reacted similarly