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2: Atoms and Elements

Last updated

Jul 17, 2023
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- 1.5: States of Matter
- 2.1: Cutting gold until you get atoms

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2.1: Cutting gold until you get atoms
If you continue cutting a pure substance into smaller and smaller pieces, you will eventually reach a limit, a piece that cannot be cut any smaller and still be the same substance. That is the atom.
2.2: The Atom
Chemistry is based on the modern atomic theory, which states that all matter is composed of atoms. Atoms themselves are composed of protons, neutrons, and electrons. Elements are represented by an atomic symbol. The periodic table is a chart that organizes all the elements.
2.3: The Atomic Number and Mass Number
Each element has its own atomic number, which is equal to the number of protons in its nucleus. The mass number is the sum of the number of protons and neutrons. The number of neturons in an atom can be determined by subtracting the atomic number from the mass number.
2.4: Isotopes and Nuclear Symbols
The isotopes of an element have different are identified by their mass numbers. Nuclear symbols differ from atomic symbols and include both the mass number and the atomic number.

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