Trivial name for example, hydrogen ("water-producing"), oxygen ("acid-producing"), nitrogen ("soda-producing"), bromine ("stink"), and argon ("no reaction") were based on Greek roots, while the names of iodine and chlorine were derived from the Greek words for their characteristic colors. Indium, rubidium, and thallium were similarly named for the colors of particular lines in their emission spectra. Iridium, which forms compounds of many different colors, takes its name from "iris", the Latin for "rainbow". The noble gases have all been named for their origin or properties. Helium comes from the Greek "helios", meaning "sun" because it was first detected as a line in the
Shade (shadow) Shade (shadow) Shade is the blocking of sunlight (in particular direct sunshine) by any object, and also the shadow created by that object. Shade also consists of the colors grey, black, white, etc. It may refer to blocking of sunlight by a roof, a tree, an umbrella, a window shade or blind, curtains, or other objects. In temperate and tropical zones (most places on Earth), shade is an important issue in providing cooling and shelter from harmful heat and ultraviolet emitted by the Sun. Green plants produce shade by absorbing sunlight to invest as energy in photosynthesis to produce sugar.