OBJECTIVES:
1. differentiate elements from compounds based on their composition from the given
chemical names and formulas of elements and compounds,
2. describe briefly the history and basis of naming elements, and
3. recognize important elements and compounds that are useful to humans.
Answers
Answer:
1. Distinguished by their fixed ratio of different elements (arranged in a defined manner). As only one type of atoms makes up an element, all the properties of that atom are represented by its atom. In the case of compounds, the same type of molecules makes up the compound.
2. Chemical elements may be named from various sources: sometimes based on the person who discovered it, or the place it was discovered. Some have Latin or Greek roots deriving from something related to the element, for example some use to which it may have been put.
3. Of the approximately 115 elements known, only the 19 highlighted in purple in Figure \(\PageIndex{1}\) are absolutely required in the human diet. These elements—called essential elements—are restricted to the first four rows of the periodic table, with only two or three exceptions (molybdenum, iodine, and possibly tin in the fifth row). Some other elements are essential for specific organisms. For example, boron is required for the growth of certain plants, bromine is widely distributed in marine organisms, and tungsten is necessary for some microorganisms.