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

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   Recently updated !

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   Recently updated !

A resistor has high electrical resistance while a conductor has high conductivity. (Nicolas Thomas)
This is a table of the electrical resistivity and electrical conductivity of several materials. Included are metals, elements, water, and insulators. Electrical resistivity, represented by the Greek letter ρ (rho), is a measure of how strongly a material opposes the flow of electric current. The lower the resistivity, the more readily the […]

Table of Electrical Resistivity and Conductivity   Recently updated !

Protons and electrons stick to each other as much as they can, but kinetic energy and quantum mechanics keep them from holding still.
Protons and electrons are attracted to each other because the positive electric charge of the proton is attracted to the negative charge of the electron. But, if they two particles find each other so attractive, why don’t protons and electrons stick together? Orbits and Waves In a sense, protons and […]

Why Don’t Protons Stick to Electrons?