Molecules are the smallest particles that maintain the chemical properties of matter. Atoms are the smallest particles involved in chemical changes. Molecules and atoms are both particles that make up matter. Their mass and volume are very small. They are spaced apart from each other and are constantly moving. They are both different in type and number, and they are not electrical. Molecules are always in constant motion.

Quantum is an important concept in modern physics. It was first proposed by German physicist M. Planck in 1900. He hypothesized that the radiation energy in blackbody radiation is discontinuous and can only be an integer multiple of the basic unit of energy, thus well explaining the experimental phenomenon of blackbody radiation.

Later research showed that not only energy shows this discontinuous separation property, but other physical quantities such as angular momentum, spin, charge, etc. also show this discontinuous quantization phenomenon. This is fundamentally different from classical physics represented by Newtonian mechanics. Quantization phenomena are mainly manifested in the microphysical world. The physical theory that describes the microscopic physical world is quantum mechanics.

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Characteristics of molecules:

1. There are gaps between molecules. For example: take 50 ml of alcohol and 50 ml of water. After mixing, the volume is less than 100 ml.

2. All the molecules that make up matter are constantly moving irregularly. The higher the temperature, the faster the molecules diffuse. Among solids, liquids, and gases, gas diffusion is the fastest. Since the motion of molecules is related to temperature, this motion is called thermal motion of molecules. For example: Clothes dry easily in hot weather.

3. The general molecular diameter is on the order of 10^-10m.

4. The molecules are very small, but have a certain volume and mass.

5. The molecular properties of the same substance are the same, but the molecular properties of different substances are different.

Atoms are very powerful, and the energy in the nucleus will be relatively harmful when released. But there is also an advantage, that is, words can help us if we make good use of them. The radiation from the nuclei can be absorbed by plants to reduce our harm.

But what we can usually do is to use as few things with atomic energy as possible, so as to reduce the damage. Only by being good at observation and understanding new methods in a timely manner can we achieve better prevention.

Quantum physics is a discipline that studies the movement laws of microscopic particles. It is a basic theory that studies the structure and properties of atoms, molecules, and even atomic nuclei and elementary particles.

The breakthrough in quantum theory first appeared in the distribution of blackbody radiation energy density with frequency. In October 1900, due to Planck's explanation of the black body radiation phenomenon, Wien's law was improved, and Boltzmann's entropy formula was reinterpreted, and a Planck formula that was fully consistent with experimental data was obtained to describe black body radiation.

Planck proposed a simple formula that was in good agreement with the observational results. Experimental physicists believe that it must contain a scientific principle that has not yet been revealed.

Reference: Baidu Encyclopedia---Atoms

Reference: Baidu Encyclopedia---Molecular

Reference: Baidu Encyclopedia---Quantum

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