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Atomic Number

The number of protons in an atom. Defines arrangement of periodic table.

Atoms Practice
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Atomic Number and Mass Number

Atomic Number and Mass Number

Shows how the atomic number is determined by the number of protons and that the periodic table is arranged by increasing atomic number. Also goes into mass number, showing examples that help illustrate that the mass number is the sum of the protons and neutrons.

https://www.youtube.com/watch?v=-K76d-g2Ryc (3:51)

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