Chemistry

• Matter


  Anything that has mass and takes up space
• Pure Substances 


  One kind of atom or element on the periodic table
• Elements


  Viewed on the periodic table

  • Simplest pure substance which cannot be separated
• Compounds


  Combined chemically according to their ratios

  • can be separated through chemical means
• Homogeneous Mixture


  A mixture where more than one components are present which are mixed together, so that only one element can be seen

  • Solution = DISSOLVED
  • Solvent = Dissolves solute to form a solution
  • Solute = Dissolves into solvent
  • Alloy = A solid metallic solution made up of 2 or more nickels = Homogeneous mixture of one or more metals which changes the properties of the original metal
• Heterogeneous Mixture

  Elements that can all be seen, even though they are mixed

  Mechanical Mixture = can see two or more phases present in the mixture

  Suspensions = Particles which can be seen and settle overtime by gravity

  Colloids = appear homogeneous and particles will never settle

  • too large to be classified as a solution
• Physical Property - 

  can be changed without chemically changing the substance itself

  • Determined using qualitative and quantitative properties  [Ref Unit 1 Notes for definitions]
  • Measure volume, temperature, density
• Physical Change

   Changing the composition of a substance without introducing new substances

  • Ex; a can which has been compressed, empty of soda, etc; 
  • Changing its shape 
  • Identity, particles and properties remain the same 
  • Changes of state are included in this category [particle distribution]
  • Dissolving
• Characteristic Physical Properties - Describes it [using given adjectives]

  • Pure substances each have unique properties
  • Differentiates similar looking substances 
  • Density units = g/mL [liquid] g/cm^3 [solid]
  • How much stuff is in a given space ex; mercury 

  Examples of terminology for physical properties can be viewed in binder
• Chemical Change

  Involves chemical changes to a substance [making one for more substance]

  • Basically something happens which we don’t expect to happen [rearrange particles]
  • Ex; Oxidization, Flammability 
  • A tissue is flammable while a glass beaker is not 
• 5 evidences of Chemical Change

  • New colour
  • Change in energy [heat or light]
  • New gas or odour
  • Produces a solid [precipitates] - can look different [ex; a raw and cooked steak - same solid, different colour = new solid]
  • Formation of bubbles [gas]
• Chemical Property

  Ability to undergo chemical changes [making more or new products]

  • Reactivity - Able to react with other chemicals [how easy it is]
  • Flammability - does it burn easily [in the presence of oxygen]

  [Fibres and papers burn easily, but metals don’t]

  • Oxidation - The tendency of a material to rust [commonly metals rust]

  Chemical properties can only be identified when the object reacts
• Density - the amount of matter in a given space [more particles, same space = more density] [same particles, less space = more dense]

  • Size of particles = increased matter = more density

  Mass[m]:  Measuring how much matter is in a sample 

  • More or larger particles = more mass
  • mglass

  Volume[V]: How much space a sample of matter takes up

  • Measured in L

  Density - How much matter[m] is in a given space[V]

  • Can be seen as D,d,p
  • [d] Density = Mass [m] /volume [V]
  • Can be graphed 
• What is the difference between compounds and mixtures

  Compounds combine to make a new particle while mixtures don't make a new particle
• Mechanical Mixture


  You can see 2 or more things
• Mechanical Mixture


  2 or more phases
• Suspensions


  Particles that can be see with the eye

  Gravity settles the particles

  Example: Ketchup, Orange Pulp in juice
• Colloids


  Appear homogeneous

  Particles will never settle but too large to classify as a solution

  Tyndall Effect - If it shines through a glass, its a solution. If not, its a colloid
• Alloy


  A solid metallic solution make up of 2 or more metals

  Homogeneous mixture of one or more metals which changes hte properties of the original metal
• Dalton's 5 Postulates of Atomic Theory


  • All elements are made up of atoms
  • Atoms of the same element have the same shape and mass
  • Atoms of different elements differ in shape and mass
  • Cannot be created or destroyed
  • Combine in ratios to form compounds
• Dalton's Experiments


  1. Combine and broke apart elements and compounds into ratios

  2. Compounds are combinations of fixed element ratios [atoms do the same]
• Compound example


  • Hydrogen:Oxygen 2:1
• J.J Thompson


  Added positive and negative charges [electrons]
• Atoms


  • Made from positively charged substances which contain negatively charged electrons
• Rules for charged objects

  • Negative repels negative
  • Positive repels positive
  • Negative attracts positive
• Thompson's Experiment: Cathode Ray Tube


  Charged plates where put on each side, particle direction was bent and repelled negative attracts positive
• Thompson was the first person to discover that atoms can be broken down [particles that are smaller exist]
• Each piece of matter is balanced by a equal number of positive and negatively charged atoms
• Earnest Rutherford

  Gold Foil Experiment
• Rutherford's Gold Foil Experiment

  1. Positive particles fired at gold foil

  2. Many particles went straight through

  3. Some were deflected or bumped into something that is "solid"
• Rutherford's Atomic Model


  • Atoms are mostly empty space, positives are tiny, and negative are spread outwards
  • Nucleus is positive and repels any incoming positive charges
  • Atoms are empty space
  • Atoms have a positively charged centre which repelled the positive charged bullets [alpha particles]
  • Rutherford's nucleus is tiny compared to the atom
  • Nucleus is found in an atom and alpha particles are always moving
  • Atoms positively charged particles are inside the nucleus
  • Negatively charged particles sit outside the nucleus and on the edges of the atom
• Bohr's Model - 1913

  • Negatively charged electron will always be ATTRACTED to the positive nucleus [will collapse]
  • Negative electrons should lose energy and spiral inwards, which collapse into the nucleus
• Bohr's Proposed Model


  1. Electrons are stuck in energy levels [orbits] - like how planets circle the sun

  2. Energy levels are located at certain distances from the nucleus
• Bohr's Experiments


  1. Heated elements and compounds, which gave off colours of light

  2. Using a prism to separate the light into colours

  3. Measured the energy of the colours
• Bohr's model explains why fire that is red has less energy than fire which is blue
• Metals

  • Great conductors of heat and electricity
  • High luster [metallic]
  • Ductile and malleable
• Non Metals

  • Poor heat and electricity conductors
  • Solid non-metals tend to be brittle [not workable]
  • Dull
  • Many are gases at room temperature
• Alkali Metal [are metals, but specifically alkali metals] 

  • Opposite of acid
  • Extremely soft
  • Highly reactive metals
  • Lithium, Sodium, Potassium = low density and float on water
  • Combine easily with other elements and compounds
  •  Don’t hangout by themselves and commonly are in compounds due to their high reactivity
• Alkaline Earth Metals 

  • High lustre but not as soft or reactive compared to Alkali Metals
  • Make bright, colourful flames when lit on fire [fireworks]
• Noble Gasses [opposite of halogens]

  • Not reactive at all
  • Extremely stable
  • Clourless, odourless, tasteless, and glows another colour when electrical currents pass through 
  • Stay for long periods of time
  • Acts as good insulation ex; Argon is put between two window panes to act as insulation and will never react