History of quantum mechanics

Quantum mechanics is a branch of science that helps us explain the behavior of molecules and atoms, which are the smallest parts of matter. It was developed in the early 20th century, when scientists noticed that the everyday laws of physics didn't always seem to apply to these tiny objects. For example, when a light is shone on an atom, it can behave both like a particle (an object with a definite size and shape) and like a wave (a spread of energy). This strange behavior showed that different rules were needed to understand how atoms and molecules worked. Quantum mechanics was the first attempt to create these special rules.