Chemistry / Unit 2 Chem 0217 short lesson, about 20 seconds
Atomic Number
Captions available
The idea
The atomic number is the number of protons in an atom's nucleus, and it alone defines which element the atom is.
In practice
Any atom with six protons is carbon, atomic number 6, no matter how many neutrons or electrons that particular atom happens to have.
Where people slip
Neutron count never sets identity; atoms with the same protons but different neutrons are still the same element.
Your place on the trail
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