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Chemistry Units! Constants! Symbols! Formulas! Math Home Page! Constants!

First we have to tell you what a constant is. Simply put, a constant is a number or measurement that is always the same. No matter where, when, or what condition, when you have a formula which asks for a constant, it is always the same number. Here are some examples...

Avogadro's Icon

6.02 x 1023
NAME: Avogadro's Number
WHAT: It tells you the number of atoms in a mole or the number of molecules in a mole of a substance.
Electron Mass

NAME: Mass of an Electron
WHAT: We talk about electrons spinning around the nucleus of an atom. Well the me is the mass of one of those electrons.
Neutron Mass

NAME: Mass of a Neutron
WHAT: In the nucleus of an atom there are neutrons and protons. A neutron has this much mass.
Proton Mass

NAME: Mass of a Proton
WHAT: In the nucleus of an atom there are neutrons and protons. A proton a mass of this amount.
Planck's Constant

NAME: Planck's Constant
WHAT: Max Planck figured out that energy can be gained and lost by an atom. He used this constant to figure out how much energy. The "J" stands for Joules.
Speed of Light

NAME: Speed of Light (in a vacuum)
WHAT: Scientists figured out that light travels always at the same speed in a vacuum. The number is really 299,792,458 meters per second, but we abbreviate it.

9.8 m/s2
NAME: Acceleration of Gravity of Earth
WHAT: What if you drop a ball from a height? It speeds up as it falls. The amount it speeds up (acceleration) is because of gravity.
Atomic Mass Unit

NAME: Atomic Mass Unit (also called a Dalton)
WHAT: It is 1/12 the mass of a Carbon-12 atom. It is the basis for figuring out the mass all other atoms.
Electron Charge

NAME: Charge of an Electron
WHAT: This is the charge of one electron which is flying around the nucleus.
Universal Gas Constant

.082 Latm/molK
8.3 J/molK
1.987 cal/Kmol
NAME: Universal Gas Constant
WHAT: This constant is used in the Universal Gas Law "PV=nRT". It has the same value for all gases. You use a different value depending on what measurements your formula uses.

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