Copper compound colours and transition metals?

Question

Few questions:

1. What are the colours and states of the following please:
Copper (II) oxide
Copper (II) hydroxide
Copper (II) nitrate
Copper (II) sulphate
Copper (II) carbonate
Copper (II) chloride

2. Is this the same trend for other compounds which are carbonates, suplhates, nitrates e.t.c. (same colours and states or are they all different?)

3. The (II) has something to do with variable valency - what does the (II) mean and can someone telll me what variable valency is all about with transition metals as I don't get it, e.g. you can have cu 1+ and cu 2+ but there's only 3 electrons in the outer shell of copper so surely is should be cu 3+ or cu5-??

thanks.

Answer 1

1.

Copper oxide: black powder

Copper hydroxide: pale blue gelatinous gunk

Copper nitrate: bright blue crystalline solid

Copper sulphate: bright blue crystals if the pentahydrate; pale blue to pale grey crystals if anhydrous

Copper carbonate: blue-green powdery solid

Copper chloride: light green solid



2. Not quite sure what you're asking here, but if you mean "Are all transition metal sulphates/nitrates/etc the same colour?" the answer is no. Copper sulphate is blue, iron (II) sulphate is blue-green, iron (III) sulphate is yellowish, chromium sulphate is dull purple, and so on.



3. Cu (II) translates as Cu 2+. The reason for copper having only 1+ and 2+ oxidation states availible is due to the ionisation energies. The energy it takes to remove the first electron is around 750 kJ/mol, the energy it takes to remove the second electron is around 2000 kJ/mol, and the energy it takes to remove a third electron is a whopping 3500 or so kJ/mol. The first two can be overcome, the third, almost never.



Copper has 11 electrons in its outer shell: 10 d electrons, and 1 s electron.

Answer 2

Copper Compounds Color

Answer 3

Magnesium is an element, a metal. It is silvery grey in colour and has lustre. whereas Magnesium Oxide is a compound made from reaction of magnesium and oxygen. It is a powdery substance and is white in colour

Answer 4

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