Chromium
Chromium was discovered in 1797 by French chemist Louis- Nicolas Vaquelin (1763-1829) in a mineral known as Siberian red lead. The element was named after the Greek word chroma, meaning "color"
because many chromium compounds have a distinctive color, ranging from purple to black to green to orange to yellow.
Sodium
Despite SODIUM being too reactive to occur free in nature, it’s present in the Earth’s crust in many different compounds.
It’s a very familiar element as it forms many useful compounds. Some of the most common are: table salt (NaCl), soda ash (Na2CO3), baking soda (NaHCO3), caustic soda (NaOH) and borax (Na2B4O710H2O). Sodium vapor is used in streetlights, producing a brilliant yellow light.
