Final answer:
Avogadro's observation that equal volumes of gases contain the same number of molecules under identical temperature and pressure is critical evidence supporting atomic theory, leading to what is known as Avogadro's Law.
Step-by-step explanation:
Avogadro's Law and Atomic Theory Support
The evidence supporting the atomic theory includes Avogadro's observation that, under the same conditions of temperature and pressure, equal volumes of any two gases contain the same number of molecules. This concept originated from Amedeo Avogadro's hypothesis in 1811, where he stated that equal volumes of all gases, measured under the same conditions, contain the same number of particles. Despite initial skepticism, this hypothesis is now a fundamental gas behavior principle known as Avogadro's Law. It states that the volume (V) of a gas is directly proportional to the number of moles (n) of gas in the sample, at constant temperature and pressure. When we talk about Avogadro's number, we refer to the number of particles in one mole, which is 6.022 × 1023.
Avogadro's hypothesis is crucial because it helps to explain why gaseous volumes can be universally compared and utilized to infer the quantity of substance (moles) present. For instance, at standard temperature and pressure, 1 mole of any gas occupies 22.4 L, regardless of the type of gas. This forms the basis for calculations in chemistry that involve gases, allowing scientists and students alike to understand and predict how gases will behave under varying conditions.