Chemistry C4

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Definitions

Atom - the smallest part an element can be divided into using a chemical reaction

Element - contains atoms which are all identical

Molecule - two or more atoms, chemically bonded. The atoms may be the same or different

Compound - made up of two or more different elements chemically bonded together

columns = groups

rows = periods

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Groups and Relative mass/charge

Group 1 - alkali metals Group 7 - halogens

Group 2 - alkali earth metals Group 0 - noble gases

Relative mass and charge

Protons - charge = +1, mass = 1

Neutrons - charge = 0, mass = 1

Electrons - charge = -1, mass = 0.0005


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Shell rules and number of neutrons equation

Shell rules

1st shell - 2 electrons 3rd shell - 8 electrons

2nd shell - 8 electrons 4th shell - as many as you like

Neutrons = mass number - atomic number

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Short hand notation

Order

  1. Number on first
  2. Number on second
  3. Number on third
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Properties of metals

  • strong
  • solid at room temperature
  • hard
  • malleable
  • shiny
  • good conductor of heat and electricity
  • high density
  • high melting point
  • ductile
  • sonorous
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Dobereiners Periodic Table Limitations

  • only three triads
  • didn't include all of the elements
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Alkali metals and ... equations

Alkali metals and water

metal + water -> hydrogen + metal hydroxide

Alkali metals and chlorine

metal + chlorine -> metal chloride

Alkali metals and oxygen

metal + oxygen -> metal oxide

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Halogens

  • As you go down the group, the melting/boiling points increase
  • The halogens are volatile (they turn into a gas very easily)
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State Symbols

  • Solid - (s)
  • Liquid - (l)
  • Gas - (g)
  • Aqueous solution - (aq) - dissolved in water
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Ionic bonds/compounds

Ionic bonds - between metals and non-metals

Properties

  • made of crystals
  • often soluble in water
  • high melting points
  • conduct electricity when molten or dissolved but not when solid
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Properties of salt

Salt - Na+Cl-

Properties

  • usually soluble in water
  • conducts electricity whne dissolved and molten (ions are free to move)
  • does not conduct electricity when solid (ions are fixed)
  • high melting/boiling points (strong attractions)
  • crystalline appearance (lattice arrangement)
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Flame Colours

Lithium - bright red

Potassium - light pink/lilac

Sodium - orange (bright)

Calcium - red/orange

Barium - green/yellow

Copper - green/blue

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Charge per group

Group 1 -> +1  Group 2 -> +2 Group 3 -> +3

Group 4 -> N/A Group 5 -> -3 Group 6 -> -2

Group 7 -> -1 Group 0 -> N/A

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