January 24, 2016

The Colors Of The Elements

A guest article by Joseph Friedlander

I wanted to write a simple article to show children to get them interested in chemistry. There is no gigantic cosmic idea here, just Wikipedia pictures and the common theme of pretty chemicals. This article is best shown to children with an adult by their side to explain things.

A good site to have the kids look at is http://images-of-elements.com/

To go to any Wiki element page start here for easy links https://en.wikipedia.org/wiki/List_of_elements

I have long had an interest in the elements and part of that has been the colors of the elements. 
Since most elements are metals and since most metals are described as metallic looking or silvery, pronounced colors among elements are rare.  Some gases are colorless as well. So the elements that display colors are few in number.

(A side point about most elements being metals--astronomers in fact refer to anything heavier than hydrogen or helium as metals --even gasses like oxygen or chlorine -- https://briankoberlein.com/2014/04/23/hydrogen-helium-metal/ and speak of the metallicity of stars) 

There are of course many colorful chemicals. 

from Wiki--
II) sulfate pentahydrateCuSO4 · 5H2OBlueLarge crystals of copper sulfate
Copper(II) benzoateC14H10CuO4BluePowdered copper benzoate
Cobalt(II) chlorideCoCl2Deep blueCobalt(II) chloride
Cobalt(II) chloride hexahydrateCoCl2 · 6H2ODeep magentaCobalt(II) chloride hexahydrate
Manganese(II) chloride tetrahydrateMnCl2 · 4H2OPinkManganese(II) chloride tetrahydrate
Copper(II) chloride dihydrateCuCl2 · 2H2OBlue-greencopper(II) chloride dihydrate
Nickel(II) chloride hexahydrateNiCl2 · 6H2OGreenNickel(II) chloride hexahydrate
Lead(II) iodidePbI2YellowLead(II) iodide
There are colorful chemicals under the flame test

Because each element has an exactly defined line emission spectrum, scientists are able to identify them by the color of flame they produce. For example, copper produces a blue flame, lithium and strontium a red flame, calcium an orange flame, sodium a yellow flame, and barium a green flame.
Flame tests | Causes of Color - Webexhibits


from Wiki--
LiLithiumCarmine; invisible through green glassFlammenfärbungLi.png
NaSodiumIntense yellow; invisible through cobalt blue glassFlametest--Na.swn.jpg
Cu(II)Copper(II) (non-halide)GreenFlame test on copper sulfate
CaCalciumBrick redFlammenfärbungCa.png
StrontiumCrimson to Scarlet, yellowish through green glass and violet through blue cobalt glassFlammenfärbungSr.png
and similarly under the bead test https://en.wikipedia.org/wiki/Bead_test

Chemicals can color fire https://en.wikipedia.org/wiki/Colored_fire

from Wiki--
Carmine (Dark Red)Lithium chlorideFlammenfärbungLi.png
RedStrontium chloride or Strontium nitrateFlammenfärbungSr.png
OrangeCalcium chlorideFlammenfärbungCa.png
YellowSodium chloride (table salt) or Sodium carbonateFlametest--Na.swn.jpg
Apple GreenBorax (Sodium Borate)FlammenfärbungB.png
GreenCopper(II) sulfateBoric AcidFlametest--Cu.swn.jpg
BlueCopper(I) chlorideButaneFlametest--.swn.jpg
Violet3 parts Potassium sulfate, 1 part Potassium nitrate (saltpeter)
PurplePotassium chlorideFlammenfärbungK.png
There are colorful alloys. The diagram below shows how you mix gold copper and silver to get red gold , white gold or even green gold. Using Indium you can get blue and purple gold too. You can get even more colors by making crystals of metal with colorful oxidation states, especially transition elements. 


A page for older readers on this http://www.chemguide.co.uk/inorganic/complexions/colour.html

By Original image: Metallos - Translated version of File:Ag-Au-Cu-colours-It.svg (using texts from File:Ag-Au-Cu-colours.png), 

There are colorful minerals, some precious https://en.wikipedia.org/wiki/Gemstone

All the above are colorful but are not pure elements. This article focuses on the colors of elements.

To go to any Wiki element page start here for easy links https://en.wikipedia.org/wiki/List_of_elements
Many elements have allotropic states that can give a different color to some temperature ranges of the element. Explained in more depth here  https://en.wikipedia.org/wiki/Allotropy#List_of_allotropes

Everybody's favorite-- gold.
Copper can be pinkish orange and brownish depending how tarnished the surface has been explosed.
Osmium has a blue-gray tint 

Lead has a slight blue to it when pure but gets gray as it tarnishes

The liquid sulfur is red and hot above 200 C, the yellow is cold and solid. It burns blue.
Johannes 'volty' Hemmerlein

Carbon is black or can be clear as a crystal (diamond) 
File:Coal anthracite.jpg
Boron can be black brown or File:Bor 1.jpgsilvery.

Bromine is Orange-BrownBromine 25ml (transparent).png
W. Oelen
Liquid (cold) Oxygen is blue; gaseous oxygen is invisible
File:Liquid Oxygen.png
Dr. Warwick Hillier / Australian National University
Chlorine Gas is green-yellow
File:Chlorine ampoule.jpg
W. Oelen

and when cold or under pressure is a yellow liquid.
File:Liquid chlorine in flask.jpg


  Fluorine  Gas  when warm is pale yellow  https://en.wikipedia.org/wiki/Phases_of_fluorine;

Link for older readers on the difficulty of preparing a container to hold it in with a picture of the gas in a clear container  http://periodictable.com/Elements/009/

 cold  Fluorine is a yellowish liquid; in each case fainter than chlorine.
File:Liquid fluorine tighter crop.jpg
Prof B. G. Mueller

Iodine is blue black as a solid
File:Sample of iodine.jpg 
Iodine can be purple as a gas
Round bottom flask filled with violet iodine vapor
Matias Molnar

Phosphorous has many allotropic states https://en.wikipedia.org/wiki/Allotropy#List_of_allotropes  of color like sulfur including white red yellow scarlet violet and black  
Peter Krimbacher
Selenium also has allotropic colors or red black and gray

W. Oelen

Antimony has allotropic colors of blue-white, yellow and black and in metaloid form is silver grayish like silicon
A clear vial containing small chunks of a slightly lustrous black solid, labeled "Sb".
Ondřej Mang
Arsenic has allotropic colors of gray yellow and black
File:Native arsenic.jpg
Aram Dulyan

My advice to a child just beginning to study chemistry would be to learn the periodic table by groups and try to learn the personality and uses of each element (up to Uranium or Plutonium which are elements number 92 and 94.). 

Once you know the players, the game makes much more sense.

If you liked this article, please give it a quick review on ycombinator or StumbleUpon. Thanks

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