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Atoms and Elements. Subatomic Particles. Atom - Smallest particle of an element. Subatomic Particles - Atoms are composed of protons, neutrons, and electrons. Nucleus - Small dense positively charged center of an atom .
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Subatomic Particles • Atom-Smallest particle of an element. • Subatomic Particles- Atoms are composed of protons, neutrons, and electrons. • Nucleus- Small dense positively charged center of an atom. • Proton- Subatomic particle that has a positive charge and is found in the nucleus of an atom. • Electron- negatively charged subatomic particle found in an area outside the nucleus of an atom. • Neutron- Subatomic particle with no electric charge that is found in the nucleus of an atom.
Atoms have their electrons arranged in layers called shells • 1st level- 2 electrons max. • 2nd Level- 8 electrons max. • 3rd level- 18 electrons max. • 4th level- 32 electrons max.
Using the Periodic Table to understand makeup of atoms • Atomic Number- Number of protons in the nucleus. • Atomic Mass- Average of the masses of the existing isotopes of an element. • Mass number- the sum of the protons and neutrons in its nucleus.