Final answer:
Thomson's and Millikan's experiments were essential for understanding the properties of electrons, crucial subatomic particles that can't be observed directly. Their work led to the determination of the fundamental constants like the electron's charge and mass, enabling the development of modern atomic theory.
Step-by-step explanation:
Experiments such as those conducted by J.J. Thomson and Robert A. Millikan were vital for inferring information about electrons because electrons are too small to be observed directly. Thomson's experiments in 1897 provided the first evidence of subatomic particles through the measurement of the mass-to-charge ratio of electrons. He deduced that electrons had a negative charge and were a fundamental component of all atoms.
In 1909, Millikan's oil drop experiments enabled the precise measurement of the charge on an electron. By adjusting the strength of an electric field to counteract gravity, Millikan could determine the charge on individual electrically charged oil droplets. Combining this knowledge with the mass-to-charge ratio found by Thomson allowed scientists to calculate the electron's mass.
Understanding the properties of electrons, such as their charge and mass, was a significant leap in the field of physics and chemistry, enabling the development of modern atomic theory and contributing to our knowledge of the fundamental constants of nature.