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.
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
What is the atomic number of carbon?
Mass number of an atom
the sum of its protons and neutrons
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)
Naturally occuring carbon contains trace amounts of it
Half life (the time it take for one half of the nuclei to decay) is 5730
Atomic Weight of a naturally occuring element
the average mass of its atoms.
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.
Atomic Mass Unit
exactly 1/12 of the mass of 12C (whose atomic mass is 12). Therefore carbon would contain 12 atomic mass units.
Molecular Weight of a compound
the sum of the atomic weights of all the atoms in the molecule