KEY TAKEAWAYS •
An atom consists of at least one proton, usually some neutrons, and electrons.
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Protons and neutrons have sub-particles called quarks that are held together by gluons.
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Protons are positively charged, neutrons are neutral, and electrons are negatively charged.
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There are orbitals around the atomic nucleus containing specific numbers of electrons in them.
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The valency of an atom is determined by how many electrons are in the outer orbital.
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The periodic table is set up so that elements are arranged according to their behavior chemically.
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You as a student need to memorize as much of the periodic table as you can in order to be able to do calculations in chemistry.
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A mole is defined as the amount of a substance that contains exactly 6.02214076 × 1023 particles, such as atoms, molecules, ions or electrons.
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