Inorganic compounds and elements

Inorganic compounds and elements

1. Appearance: coloured crystalline substances are usually hydrated crystalline salts of transition metals

   • Blue: Copper (II)
   • Pale green: iron (II)
   • Green: Copper (II), Chromium (III) or nickel (II)
   • Purple: manganate (VII)
   • Brown: Iron (III)
   • Pink: manganese (II)
   • Yellow: Chromate (VI)
   • Orange: Dichromate (VI)

2. The colours of transition metals ions in dilute aqueous solution that change colour

   • Brown/yellow: Iron (III)
   • Green: Iron(II), Chromium (III) and nicker (II)
   • pale pink:manganese
   • colourless:Zinc (II)

3. FLAME TESTS

   • To carry out flame tests: dip a nichrome wire loop into concentrated hydrochloric acid and then holding over a hot Bunsen flame, until no colour is produced. This is to remove any impurities.
     • The reason we see colours from a flame test , is because the electrons on the outside sheel get excited and jump up and energy level, as they jump back down they release energy in the form of visible light. when they move back down phontons are released.
     • Yellow: Sodium ion
     • Lilac: Potassium ion
     • Brick red: Calcium ion
     • Red: lithium or strontium ion
     • Pale green: Barium ion
     • Colourless: Magnesium ion

4. Heating( action of acid and possible source)

   • Gases or vapours may be evolved on heating a solid compound
     • if there is CO2: carbonates of metals other than group 1
     • Oxygen: than its from group 1 nitrates (other than li_
     • Oxygen and nitrogen dioxide: Nitrates other than Na or K
     • Water:Hydrated salts

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