Chemical Reactions Section 2.2

Learning Objectives Explain how the number of valence electrons of an atom is related to its chemical properties Explain the relationship between atoms, molecules, and compounds Explain what has occurred when a reaction reaches dynamic equilibrium Identify the reactants & products of a chemical reaction

Molecule Vs. Compound Molecule = two or more atoms joined together N2 Compound = Two or more elements make up the molecule H2 O3 H2O NaCl

Chemical Reactions Happen because atoms want an octet (8 electrons) in their valence shell Chemical reactions create molecules & compounds Nobel Gases  Are unreactive Already have an octet in their valence shell

Chemical Reactions (Continued) Described by chemical equations Reactants = things you start out with in a reaction Products = things that are created by the reaction Coefficients = Numbers before reactants or products that tell the number of things in a reaction

Dynamic Equilibrium Reactions don’t stop! They reach dynamic equilibrium Dynamic equilibrium = the reaction is making products & reactants at the same rate Shown by double arrows ↔ or