sentence: Most metals are gray or silver.
sentences_before: It is very flexible and ductile. That means that it can be stretched into wires easily. Copper is also very soft, it has a Moh's hardness of 2,5 to 3. That means that it is harder than a fingernail but softer than a steel pocketknife. It is also one of the few colored metals.
sentences_after: Gold, copper, and osmium are the only three colored metals. In other words, it turns green because it oxidises. Copper corrodes in solutions having sulfides. It reacts with solutions of hydrochloric acid or ammonia containing oxygen. It can also dissolve in a mixture of hydrogen peroxide and hydrochloric acid.
concept_name: metal
headings: Copper Properties Physical properties
categories: Chemical elements Metals