What Are Atoms?

What Are Atoms?

1. The basic units of matter and the defining structure of elements.

2. Three particles

   • protons
     • Positively charged particles found within atomic nuclei.
     • The number of protons in an atom is unique to each element.
     • The number of protons in an atom is referred to as the atomic number of that element.
   • neutrons
     • Neutrons are uncharged particles found within all atomic nuclei (except for hydrogen).
     • A neutron's mass is slightly larger than that of a proton.
   • electrons
     • Electrons are extremely lightweight and exist in a cloud orbiting the nucleus.
     • The electron cloud has a radius 10,000 times greater than the nucleus.
     • An atom's electron configuration refers to the locations of the electrons in a typical atom.

3. Protons and neutrons are heavier than electrons and reside in the nucleus at the center of the atom.

4. nucleus

   • Virtually all the mass of an atom resides in its nucleus.
   • The nucleus is held together by the strong force, one of the four basic forces in nature.

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