No, I don't agree with the statement that the smallest particle that can exist independently for all elements is an atom. The reason is that there are subatomic particles, such as protons, neutrons, and electrons, which can exist independently outside of an atom.
Atoms are indeed the basic building blocks of matter and are composed of protons, neutrons, and electrons. However, these subatomic particles can exist independently under certain conditions. For example:
Protons: Protons are positively charged particles found in the nucleus of an atom. They can exist independently outside of the nucleus in various contexts, such as in high-energy particle interactions or in the form of cosmic rays.
Neutrons: Neutrons are electrically neutral particles also found in the nucleus of an atom. They can exist independently outside of the nucleus and are commonly observed in various nuclear processes, including radioactive decay.
Electrons: Electrons are negatively charged particles that orbit the nucleus of an atom. They can be stripped off from an atom, resulting in negatively charged ions, or they can exist independently as free electrons in various situations, such as in metals or in plasma.
So, while atoms are the basic units of matter, the particles they are composed of can exist independently outside of the atom under certain conditions. It's important to note that the behavior of these subatomic particles can be influenced by external factors, and they may not remain stable in isolation for extended periods due to their interaction with the surrounding environment.