Atoms

• Atom


  Basic unit of matter and the defining structure of elements. It is the smallest particle of an element that retains the chemical properties of that element. Atom serve as the building block for all substances in universe
• Protons


  Positively charged particles. It is located in the nucleus. The number of protons determine the atomic number and identity of the element
• Neutrons


  Neutral particles or those without charge. It is also located in the nucleus. Neutrons combined to the atoms mass and can vary in number leading to different isotopes of an element
• Electrons


  Negatively charged particles. The orbit the nucleus in regions called electron clouds or orbitals. The arrangements of electrons determine the atoms chemical behavior
• Atomic number


  The number of protons in an atom's nucleus which defines an element
• Mass number


  The sum of protons and neutrons in the nucleus
• Isotopes


  Atoms of the same element with the same number of protons but different numbers of neutrons
• Charge


  Atoms are usually electrically neutral (# of protons = # of electrons). If electrons are gained or lost the atom becomes an ion (positively or negatively charged)