Chemistry Basics

Chemistry Basics

1. Atoms

   • Contain protons, neutrons (middle) and electrons (outer)
   • Protons = positive Electrons = negative Neutrons = neutral
   • Atoms = neutral charge
   • Atomic number = proton number Mass number = protons + neutrons

2. Elements & Compounds

   • Element = substance that has same number of protons in nucleus
   • Element examples: hydrogen, iron, oxygen
   • Compound = substance formed of 2 or more elements that are chemically bonded in fixed proportions

3. Formulae & Equations

   • Elements and compounds are represented by symbols (i.e. H2)
   • Both sides of the equation must be balanced

4. Isotopes

   • Isotopes = different forms of the same element which have the same amount of protons and different amounts of neutrons
   • Same atomic number, different mass number
   • Relative atomic mass = average mass of atom