How do we represent atoms without drawing all the subatomic particles?

Atoms can be represented by their chemical symbols. For example, H is hydrogen, He is helium, etc. All the known elements are arranged on the periodic table, which displays all the elements and their properties.

The periodic table is useful in many ways other than simply memorizing the chemical symbols for all the elements. It can be used to discover trends in groups and families of elements. Elements on the periodic table are arranged into groups (arranged vertically) and into periods (arranged horizontally). There are eight groups of representative elements (main-group elements) and ten groups of transition elements (transition metals) which behave differently than the main-group elements. There are also the lanthanide (rare earth) elements which occupy the bottom periods of the periodic table.

For our purposes in the study of earth science, we need only know the basic structure and symbols of the elements. The information needed about each element can be gained from a simplified chart like the oxygen atom pictured above. The atomic number is on the top (8 protons), the chemical symbol is O for oxygen, and the atomic mass (mass number) is on the bottom. To learn more about the periodic table, see the chemistry section.