Scientific

Avogadro's Number

Definition

The exact number of elementary entities (atoms, molecules, or ions) in one mole of a substance: 6.02214076 × 10²³ per mole.

Explanation

One mole of carbon-12 atoms weighs exactly 12 grams and contains 6.022 × 10²³ atoms. This enormous number bridges atomic-scale masses and laboratory-scale masses: one water molecule has a mass of 2.99 × 10⁻²⁶ kg, but one mole of water (18.015 g) is easily measured on a balance. Since 2019, Avogadro’s number is fixed by definition, making the mole independent of any physical artifact.

02

RELATED ARTICLES

Temperature Scales Explained: Celsius, Fahrenheit, and Kelvin

A complete guide to the four temperature scales in scientific and everyday use—Celsius, Fahrenheit, Kelvin, and Rankine—including their history, conversion formulas, and where they intersect.

 Speed Units Guide: MPH, KM/H, Knots, and Mach

A complete reference for speed units used around the world — from everyday driving speeds to the velocity of light.

 Energy Units Guide: Joules, Calories, BTU, and Kilowatt-Hours

A complete reference for energy units across physics, food science, electrical engineering, and fuel — with key conversions and real-world examples.
03

RELATED TERMS

Absolute Zero

The lowest possible temperature: 0 K, -273.15°C, or -459.67°F.

Calorie

A unit of energy. The small calorie (cal) heats 1g of water by 1°C; the food Calorie (kcal) is 1000 small calories.

Mach Number

The ratio of an object's speed to the speed of sound in the surrounding medium.

Light-Year

The distance light travels in one year in vacuum: approximately 9.461 trillion kilometers.

Electronvolt

A unit of energy equal to the kinetic energy gained by an electron accelerated through 1 volt.