How can i know the color in chemistry?

Question

How can i find the color of Potassium and other elements, compounds, or molecules?

is there are formula, do i need an instrument?

Also, this is for the SAT Chemistry subject test, so if there is no formula or way to do it on paper, do i just memorize it?

NEED HELP!!! thanks

Answer 1

Only the transition metals form coloured ions / compounds.  For these, the colours vary with different oxidation states.  Some elements are coloured as well, especially the halogens.

Look here:

http://www.webelements.com/compounds.htm...

Click on an element, then click on a particular compound and you will find its colour.  It not only varies between oxidation states, but also within different compounds of that oxidation state.  For example, copper (II) oxide is black, but copper (II) sulphate is bright blue when wet, white when anhydrous.

This version of this site will help with colours of elements:

http://www.webelements.com/index.html