Part 1 of Essay
The lightest metal of all the elements is magnesium. It is the most abundant element in the Earth’s crust. Since it is so abundant, the aerospace industry uses it extensively. Magnesium is not a strong element by itself. Alloys have been developed to improve magnesium’s hardness, resistance against corrosion, and its ....

Part 2 of Essay
.... was useful for setting broken bones. There have been many uses for calcium over the years, but calcium has not been available on a large scale until the twentieth century. Calcium is a metallic element, which is fifth in abundance in the Earth’s crust. It is essential for forming leaves, bones, shells, and Portland Cement. Calcium occurs in many highly useful compounds such as marble, limestone, and chalk. Plants and animals must have calcium to live. A plant cannot grow without a good supply of calcium ....