Atoms, Ions , and Isotopes

periods - horizontal columns that share the same properties

groups - vertical columns that show amount of valence electrons

location of atomic particles and mass

• protons - nucleus - 1amu

• electrons - shells - almost 0

• neutrons - nucleus - 1 amu

• isotope - atoms that have the same number of protons but different number of neutrons

• ion - when an atom gains or loses electrons

noble gases have 8 valence electrons