Atoms, Elements and Isotopes
Understanding elements is dead simple - they're just substances made from one type of atom only. Think of them as the pure ingredients of chemistry, like having a jar filled with only carbon atoms or only oxygen atoms.
Nuclear symbols might look scary, but they're actually straightforward. The big number (mass number) sits on top, showing protons plus neutrons. The small number below (atomic number) tells you how many protons there are, which is always equal to the number of electrons in a neutral atom.
Isotopes are like identical twins with different weights - same element, same number of protons, but different numbers of neutrons. Carbon-12 and Carbon-13 are both carbon, but Carbon-13 has one extra neutron making it slightly heavier.
Relative atomic mass averages out all the different isotopes of an element. Use this formula: multiply each isotope's abundance by its mass number, add them up, then divide by the total abundance (usually 100 if given as percentages).
Quick Tip: Remember that proton number = atomic number = electron number in neutral atoms!