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Protons
positive charge, inside of the nucleus
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neutrons
neutral charge, inside of the nucleus
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electrons
negative charge, outside of nucleus (cloud)
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NOTE: The charge depends on the sharing of electrons. Giving up electrons leads to a positive charge and gaining electrons leads to a negative. The number of protons in an atom remains unchanged.
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Atomic number of an atom
the number of protons in its nucleus as well as the number of electrons that surround the nucleus of a NEUTRALLY CHARGED atom
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What is the atomic number of carbon?
6
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Mass number of an atom
the sum of its protons and neutrons
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Isotopes have the same atomic number (same number of protons) but different mass numbers bc they have different numbers of neutrons.
Examples of isotopes?
- 12C (6 protons, 6 neutrons)
- 13C (6 protons, 7 neutrons)
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14C
- Naturally occuring carbon contains trace amounts of it
- Radioactive
- Half life (the time it take for one half of the nuclei to decay) is 5730
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Atomic Weight of a naturally occuring element
the average mass of its atoms.
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Getting the atomic weight of Carbon
- (0.9889*12.0000) + (0.0111*13.0034) = 12.011
- We got this because we are going of the average mass of its atoms. These atoms are 12C, which has12.000 amu and makes up 98.89% of naturally occuring atoms and 13C, which has 13.0034 amu and makes up 1.11% of naturally occuring carbon.
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Atomic Mass Unit
exactly 1/12 of the mass of 12C (whose atomic mass is 12). Therefore carbon would contain 12 atomic mass units.
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Molecular Weight of a compound
the sum of the atomic weights of all the atoms in the molecule
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