a basic part of a whole. in chemistry, refers to a simple substance that cannot be broken down into smaller parts or changed into another substance. the basic part of an element is an atom, which contains protons, neutrons, and electrons. all atoms of an element have the same number of protons. examples of elements are hydrogen, carbon, oxygen, nitrogen, and calcium.
元素周期表
硫黄元素
an element that belongs to the nitrogen group
an element that shows the source of all things
an element whose valence is expressed by an even number, called