Besides smelling, touching and looking at the physical appearance of a substance, there are other ways to know for sure what that substance is. This is where chemical properties come in. A chemical property is a property of a substance that is observed when a substance undergoes a chemical change. The chemical change is a type of change that also changes the identity of a substance due to breakage and formation of new chemical bonds, as shown in the figure below: The figure shows a chemical change where two substances, A and B, form and break bonds with each other and other substances, C and D.
As of 2014, dimes have the smallest diameter of any U.S. coin and are also the thinnest. A penny is 1.52 mm thick with a diameter of 19.05 millimeters. It weighs 2.5 grams and has plain edges. A nickel is 1.95 millimeters thick with a diameter of 21.21 millimeters. It weighs 5 grams and has plain edges. A quarter is 1.75 millimeters thick and has a diameter of 24.26 millimeters.
As nickel was a strategic war material during World War II, nickels coined from 1942 to 1945 were struck in a copper-silver-manganese alloy which would not require adjustment to vending machines. They bear a large mint mark above the depiction of Monticello on the reverse. In 2004 and 2005, the nickel saw new designs as part of the Westward Journey nickel series, and since 2006 has borne Schlag's reverse and Franki's obverse.