9781422279526

92

Uranium

are 92 protons in the nucleus. Hydrogen, on the other hand, has only one. All samples of an element have the same number of protons, but they may have a different number of neutrons in the nucleus. Atoms with the same number of protons but different number of neutrons are called isotopes . Certain chemical properties can be interpreted based on which group or row an element resides in. Each element on the

periodic table is unique, having its own chemical and physical properties. The periodic table also gives important informa- tion such as the number of pro- tons and neutrons in the nucleus of one atom of an element, the number of electrons that sur- round the nucleus, the atomic mass, and the general size of the atom. It is also possible to pre- dict which state of matter an el- ement is designated by a chem- ical symbol—a one- or two- (or

Diagrams like this one show how elec- trons spin around an atom’s nucleus.

8