* Atomic Number: This is the number of protons in an atom's nucleus. It defines the element. For example, all carbon atoms have an atomic number of 6 because they have 6 protons.
* Mass Number: This is the total number of protons and neutrons in an atom's nucleus. It represents the approximate mass of the atom (since electrons have negligible mass).
Key Differences:
* What they represent: Atomic number defines the element, while mass number indicates the total number of nucleons.
* Impact on isotopes: Elements can have different isotopes (atoms with the same number of protons but different numbers of neutrons). This means isotopes of the same element have the same atomic number but different mass numbers.
Example:
* Carbon-12 has 6 protons and 6 neutrons, so its atomic number is 6 and its mass number is 12.
* Carbon-14 has 6 protons and 8 neutrons, so its atomic number is still 6, but its mass number is 14.
