The Periodic Table of the Elements categorizes elements primarily by the number of protons in their nucleus (atomic number) and secondarily by the characteristics they exhibit.

An element is matter than cannot be separated into different types of matter by ordinary chemical methods.

Force is applied to change an object's speed or direction of motion.

Mantle makes up 84% of the Earth's volume and has an average thickness of approximately 1,800 miles (2,900 km). It is dense, hot, and primarily solid although in places it behaves more like a viscous fluid as the plates of the upper mantle and crust gradually "float" along its circumference.

A proton is a subatomic particle found in the nucleus of an atom. It carries a positive electric charge.