Periodic table

• Dmitri Mendeleev arranged the elements in order of increasing atomic mass and placed elements with similar properties in same groups.Left gaps for undiscovered elements.
• Noble gases are group 8 are unreactive and have high melting and boiling points.Are non metals and exist as single atoms. Colourless gases. Boiling points and densities increase as you go down group as strength of van der waals forces increases.
• Halogens are group 7 they are very reactive non metals. All have low boiling points and are poor conductors, all have coloured vapours.Become less reactive as you go down group as outershell is further away from nucleus.All are diatomic
• Alkali metals are group 1. Are soft, have low densities(light,all float) and melting points.Quickly tarnish in air, are shiny when cut.Are stored under oil. Are more reactive as you travel down group as atoms are bigger so outer shell is further away from nucleus so easier to lose electron.
• Alkaline earth metals are group 2.less reactive than group 1, get more reactive as you go down group as electrons on outer shell are further from nucleus. have higher melting and boiling points than group 1 as atoms are bigger.
• Observation of lithium reacting with water

  Dull grey metal, shiny When cut, dissolves,floats,fisses
• Observation when sodium reacts with water

  White metal, shiny when cut, forms a ball, smokes, floats, dissolves
• Observation when potassium reacts with water

  Grey metal, shiny when cut, soft, lots of smoke, purple flame, smoke, dissolves, floats
• Half equation

  Na —->Na+ + e-

  K——>K+ + e-
• What are gases a room temp?

  Fluorine and chlorine
• What is a liquid at room temp?

  bromine
• What are solids at room temp

  Iodine and astatine
• Fluorine- pale yellow

  chlorine- yellow green

  bromine- red brown

  Iodine crystals- shiny purple black

  iodine solid- grey black
• When iodine is heated it sublimes.

  sublimation is solid—>gas, skipping liquid state.Iodine turns from a grey black solid to a purple vapour.

  in this experiment ice is placed at top to cool the glass.
• Group 7 half equations

  Halogen atom : Cl + e- —-> Cl-

  halogen Molecule: Cl2 + 2e- —-> 2Cl-
• What happens in a displacement reaction?

  A more reactive halogen is added to a halide solution. The more reactive halogen pushes out the less reaction halogen from solution.
• Chlorine + potassium chloride = no reaction

  bromine + potassium chloride = displacement

  iodine + potassium chloride = displacement
• Chlorine- pale green solution

  Bromine- orange solution

  Iodine- brown solution
• How do you test for chlorine?

  Damp universal indicator paper changes to red then bleaches white if chlorine is present.
• Helium- used in balloons and airships, much less dense than air so balloons float upwards when filled with it
• Neon- used in advertising signs.glows when electricity is passed through. Different coloured neon lights can be made by coating the inside of the glass tubing with other chemicals.
• Argon- used in light bulbs. Very thin metal filament inside the bulb would react with oxygen and burn away if the bulb were filled with air instead of argon. As argon is unreactive it stops filament burning away.
• Krypton- used in lasers. Krypton lasers are used by surgeons to treat certain eye problems and to remove birth marks.
• Copper oxide- black solid

  copper carbonate- green solid

  hydrated copper sulfate- composed of blue crystals

  Copper salts- usually blue in solution
• Chlorine + potassium iodide —> iodine + potassium chloride