Chemistry (I)

• Radioisotopes


  Atoms with excess charge (protons and neutrons)/energy to give off in their nucleus
• Nuclear decay


  A nucleus losing particles via electromagnetic (EM) radiation at high speeds
• Transmutation


  An atom changing elements because of the change in protons and neutrons
• Transmutation


  • Potassium-40 -> Argon-40
• Alpha decay


  When an alpha (⍺) particle (2 protons and 2 neutrons, like a helium particle) is ejected from the nucleus, making the atom undergo transmutation
• Alpha decay

  • 92U208 -> 90Th204 +2He4
  • 88Ra228 -> 86Rn224 +2He4
  • 84Po208 -> 82Pb204 +2He4
• Beta decay


  When a beta (ß) particle (electron-like properties, no mass and negative charge) is ejected from the nucleus, also making the atom undergo transmutation
• Beta decay


  • 2He6-> 3Li6 +-1e0
  • 19K42 -> 20Ca42 +-1e0
  • 11Na24 -> 12Pb24 +-1e0
• Gamma decay


  When protons and neutrons rearrange themselves in the nucleus; does not undergo transmutation
• Gamma decay


  • 56Ba137 -> 56Ba157 +0γ0
  • 88Ra228 -> 88Ra228 +0γ0
  • 84Po208 -> 84Po208 +0γ0
• Half-life


  The rate in which nuclear decay occurs in an isotope
• Half-life


  • Radon-222 decaying into polonium-218 (half life of over 4 days)
  • Carbon-14 decaying into Nitrogen-14 (half life of 5730 years)
• Alpha/beta particles + gamma rays


  • Dangerous to organisms' cells
• How radiation is dangerous to cells

  1. Radiation can enter cells

  2. Destroys the biological molecules

  3. Messes up homeostasis in the body (by causing fatal chemical reactions)
• Ionising radiation


  • Radiation that is known to displace electrons + other molecules
  • Causes irreversible damage to cells
• Radiation burns


  Caused from a short exposure to ionising radiation
• Radiation sickness


  • Short radiation exposure over a long period of time
  • Long radiation exposure over a short period of time
• Symptoms of radiation sickness


  • Nausea
  • Vomiting
  • Fever
  • Hair loss
  • Diarrhoea
• Atom


  The most basic unit of matter; cannot be broken down, created or destroyed (indivisible)
• Atom


  • Basis of elements (singular form)
  • Consists of protons, neutrons and electrons
• Atom


  • F- (fluorine anion/negatively charged ion)
  • Deuterium (hydrogen isotope, contains one proton/neutron)
• Element


  A pure substance comprised of only one type of atom
• Element


  • Found on the periodic table
  • Have atomic mass (protons + neutrons) and number (protons/electrons)
• Element


  • Selenium (Se)
  • Gold (Au)
• Compound


  A group of two or more types of elements chemically bonded together
• Compound


  • Sodium chloride (NaCl)
  • Carbon monoxide (CO)
• Molecule


  A group of two or more atoms chemically bonded (under discrete units)
• Molecule


  • Glucose (C6H12O6)
  • Carbon dioxide (CO2)
• Isotope


  A form of an element that contains the same number of protons, but different number of neutrons
• Isotope


  • Uranium-235 (92 protons, 143 neutrons)
  • Francium-215; also the most unstable isotope (87 protons, 128 neutrons)
• Atomos


  Democritus (460 BC)
• Atoms


  • Solid, hard incompressible and indestructible
  • Moved around in 'infinite numbers'
• Solid sphere model


  John Dalton (1803)
• Elements/atoms


  • Different types have varying properties, such as size, mass, chemical structure, etc
  • Atoms of the same element are identical + have similar properties (e.g. mass)
• Compounds

  • Comprised of 2 or more atoms of different elements
• Plum pudding model


  J.J Thomson (1904)
• Nuclear model


  Ernest Rutherford (1911)
• Atoms


  • Basic building block of life
  • Forms groups of a specific type which makes up elements
• Planetary model


  Niels Bohr (1913)
• Electrons


  • Could fit in certain configurations/orbits around the nucleus
  • Used heat energy to explain the theory
  • Process is called 'emission spectra'
  • Unique for each type of atom/element thus proving the unique arrangement of electrons for each of them