Daltons Atomic Theory
Law of Definite Composition: any compound is always made up
of elements in the same proportion by mass (or weight).
Law of Conservation of mass: in a chemical change, mass is
conserved; it is neither created nor destroyed.
Chemical Formula Relationships
The Number of Atoms in a Formula (for polyatomics)
Subscript numbers are used to denote the number of atoms or groups of
atoms that make up a substance.
Example: How many atoms of each element are in a formula unit
An electrolyte is a substance that, when dissolved in water, gives a
solution that can conduct electricity.
Electrolytes are also called ionic solutes.
Strong Electrolyte A substance whose solution is a good
Conversion Factors from a Chemical Equation
Consider the equation:
4 NH3 + 5 O2 4 NO + 6 H2O
The coefficients in a given chemical reaction gives us
conversion factors to get from the number of
particles of one substance to
the number of particles of a
A solution is one or more substances (the solute) dissolved in
another substance (the solvent) forming a homogeneous mixture.
The solvent is loosely defined as the substance that exists in a
greater quantity than the solute / solutes
Since many of the calculations made in chemistry deal with
very large or very small numbers it is more convenient to
express these numbers using scientific notation
A number may be written in standard exponential
Formulas of Elements
the formula of most elements is simply the elemental symbol.
Example: potassium (K); calcium (Ca); Neon (Ne)
However, seven elements form diatomic molecules as their
formula unit. Hydrogen (H2), Nitrogen (N2), Ox
Reactions and Equations
Na(s) + H2O(l) H2(g) + NaOH(aq) + heat
(s), (l), (g), and (aq) [aqueous; dissolved in water] are state
The total mass of the products equals total mass of reactants.
At this point the chemical equation is qualitat
Atomic Theory: The Quantum Model
of the Atom
Electron Energy Levels
Electromagnetic radiation: Energy particles which move as a wave at the
speed of light. The distance between waves is the wavelength. The
higher the energy, the shorter the wav