Editing Period 4 element (section)

===Copper===
[[File:NatCopper.jpg|frameless|left|upright=0.24]]
[[Copper]] (Cu) is an element in [[group 11 element|group&nbsp;11]]. Copper is one of the few metals that is not white or gray in color, the only{{citation needed|date=August 2019}} others being [[gold]], [[osmium]] and [[caesium]]. Copper has been used by humans for thousands of years to provide a reddish tint{{clarification needed|date=August 2019|reason=In elemental form? As a powder, sheets, or how in the hell at all? Compounds of copper are indeed turquoise or cyan.}} to many objects, and is even an essential nutrient to humans, although too much is poisonous. Copper is also commonly used as a wood preservative or [[fungicide]]s.