Relative: Subatomic particles have tiny masses so use relative masses instead of grams.
• Electron: An electron has about 1/ 1800th mass of a proton, positioned in the shell.
• Protons: Number of protons identifies element- atomic number, the number on top in periodic
table but on bottom in the other notation.
• Mass Number: Aka nucleon number.
• Isotopes: Atoms of the same element with different number of neutrons and mass number.
• Isotope Properties: Same number of electrons means same chemical properties as chemical
reactions involve electrons. Isotopes different physical properties e.g. boiling point.
• Ions: Cations are positively charged ion. Anions are negatively charged ion.
• Polyatomic Ions: A charge on polyatomic ion means number of electrons more/ less overall, not
for each atom in compound. Have brackets for (SO4)
2- polyatomic ions. Ignore sub- script e.g. 3 in
CO3
2-
.
• Constructing Equation:
– Cross multiply charges on ions of compounds- product.
– Remember some elements exist as diatomic e.g. N2+
– reactant.
– Balance equation normally.
– Add state symbols.
– See if need water, carbon dioxide or hydrogen to make up for missing elements in main
product.
