Chemistry

• In 1807, Sir Humphrey Davy discovered a new element: Potassium, which is found in potash.
• Lavoisier defined an element as a substance that could not be decomposed by existing chemical means.
• Who debunked phlogiston?

  Lavoisier had shown that phlogiston didn’t exist.
• Ion


  An atom that has an unequal number of protons (+) and electrons (-); this creates an electric charge
• Cation

  A positively charged ion; it has lost electrons
• Anion


  A negatively charged ion; it has gained electrons
• Cations

  • Lithium (Li)
  • Oxygen (O)
• Anions


  • Neon (Ne)
• Neon does not form an ion because it is already stable with a full shell
• Periodic Table

  • Arranged by Dmitri Mendeleev (Russia-1809) according to atomic mass to predict chemical behaviour of elements
  • Arranged by Henry Moseley (English physicist) according to atomic number and number of protons
• Periodic Law


  When elements are arranged in order of increasing atomic number, there is a periodic pattern in their physical and chemical properties
• Periods

  • Horizontal rows of the periodic table
  • Atomic numbers increase from left to right
• Groups

  • Vertical columns of the periodic table
  • Elements in a group have similar physical and chemical properties
  • Identify how many electrons are in the outermost orbital, which determines how the atoms react
• Groups

  • Group 1: Alkali metals
  • Group 2: Alkaline Earth Metals
  • Groups 3-12: Transition metals
  • Bottom 2 Periods: Rare Earth Metals
  • Group 17: Halogens
  • Group 18: Noble gases
• Alkali Metals


  • Metallic, silver-like lustre
  • High ductility
  • Excellent conductors of electricity and heat
  • Highly reactive, react very easily with halogens and water
• Alkaline Earth Metals

  • Metallic, gray-white lustre
  • Tarnish easily in air
  • Good conductors of electricity
  • React easily with halogens
  • Not found pure in nature
• Transition Metals

  • Metallic
  • Most are hard, strong, and lustrous
  • Have high melting and boiling points
  • Good conductors of heat and electricity
• Halogens

  • Non-metals
  • Highly reactive, especially with alkali metals and alkaline earths
  • Not found pure in nature due to high reactivity
  • Excellent disinfectants but also toxic in pure form
• Noble Gases

  • Non-metals
  • Odourless, colourless gases
  • Non-reactive
  • Some can be made into compounds, but it's very difficult to do so
  • Glow when electricity is passed through them
• Metals vs Non-metals

  • Metals (left side of staircase): Shiny, good conductors of heat and electricity, malleable, usually dense and solid at room temperature, readily lose electrons
  • Non-metals (right side of staircase and Hydrogen): Dull appearance, poor conductors, usually brittle, less dense, tend to share or gain electrons
• Metalloids

  • Found along the staircase (but not Aluminum)
  • Dull or shiny
  • Usually conduct heat and electricity not as well as metals
  • Often malleable
  • Exist in many forms
  • May gain or lose electrons
• Never trust a atom. They make up everything
• Element


  A pure substance that is made up of only one type of atom
• Elements

  • 118 total
  • 94 occur naturally
  • 24 have been made synthetically
• Periodic table


  Represents all the elements
• Atomic number


  The number of protons in the nucleus
• Atomic mass


  The average mass of the atoms in an element
• In a neutral atom, the number of protons equals the number of electrons
• Isotopes


  Elements that can have different numbers of neutrons in their nuclei
• Some isotopes of elements cause them to be radioactive (e.g. uranium, carbon)
• Bohr diagram


  A way to represent atoms, only works for atoms with a relatively small atomic number
• Bohr diagram

  • Nucleus - inner part with protons and neutrons
  • Energy shells - circles around nucleus where electrons are found, shells closest to nucleus fill up first
• Bohr diagram for Phosphorus

  • Atomic number: 15

  Atomic mass: 30.974

  Protons: 15

  Neutrons: 16

  Electrons: 15
• Bohr diagram for Neon

  • Atomic number: 10

  Atomic mass: 20.1797

  Protons: 10

  Neutrons: 10

  Electrons: 10
• Matter


  Anything that has mass and takes up space (has volume)
• Energy


  What something is if it is not matter
• Atom


  The basic unit of a chemical element, made up of tiny sub-atomic particles called neutrons, protons, and electrons
• Nucleus


  • The dense center of the atom, containing the protons and neutrons
• Protons

  • Sub-atomic particles found in the nucleus, positively charged, each proton gives a +1 charge, each proton is 1 atomic mass unit (AMU) big, contributing to the atom's mass and volume
• Neutrons


  • Sub-atomic particles found in the nucleus, neutral, each neutron is 1 AMU big, contributing to the atom's mass and volume