Learn about chemistry, the study of matter and its reactions. Find projects, study notes, periodic tables, and worked example problems.

A neutral tritium atom contains one proton, two neutrons, and one electron.
Tritium is the radioactive isotope of the element hydrogen. It is also known as hydrogen-3 or using the shorthand notation T or 3H in chemical formulas and reactions. The nucleus of the tritium atom, called a triton, contains one proton and two neutrons. The word tritium comes from the Greek […]

Tritium Facts (Hydrogen Isotope)

Gallium Crystals (foobar)
Gallium is a chemical element with atomic number 31 and element symbol Ga. It is considered to be a post-transition metal or basic metal. Gallium is known for its low melting point, which lends itself to the gallium spoon demonstration and even melting the pure metal in your hand. Here […]

Gallium Element Facts

Matter changes form but not identity in a physical change. A chemical reaction occurs and a new product is formed in a chemical change. (rawpixel)
Identifying chemical and physical changes and learning how to tell them apart can be confusing. Basically, both are changes in the structure of matter. In a physical change, matter changes forms but does not change its chemical identity. In a chemical change, a chemical reaction occurs and a new substance […]

Chemical and Physical Changes of Matter