A compound can be separated into the individual elements that it is comprised of and an element can separated as far as its individual atoms. An atom represents the smallest possible part of an element that still retains the properties of that element.
Definition of nickel. 1  1 : a silver-white hard malleable ductile metallic element capable of a high polish and resistant to corrosion that is used chiefly in alloys and as a catalyst â see element table. 2  2a (1) : the U.S. 5-cent piece regularly containing 25 percent nickel and 75 percent copper (2) : the Canadian 5-cent pieceb : five cents.
Nickel is one of the primary elements of the Earth's core which is thought to be made mostly of nickel and iron. It is also found in the Earth's crust where it is about the twenty-second most abundant element. Most nickel that is mined for industrial use is found in ores such as pentlandite, garnierite, and limonite. The largest producers of nickel are Russia, Canada, and Australia. Nickel is also found in meteorites where it is often found in conjunction with iron.