These are almost one-quarter of the periodic table and are mainly found in the first four periods. Of these, 11 are essential elements that our bodies need in larger amounts: oxygen, carbon ...
This video explains the periodic table, containing all the known elements arranged in groups and periods. Elements in the same group of the periodic table show trends in physical properties ...
How do we calculate mass and atomic numbers? VideoHow do we calculate mass and atomic numbers? This video is an interactive lesson in calculating an atom's mass and atomic number.