Characteristics of Matter and Calculation in Chem

• Chemistry is the study of matter and the changes it undergoes
• Matter is anything that occupies space and has mass
• Classifications of matter

  • Substances
  • Mixtures
  • Elements
  • Compounds
• Substance


  A form of matter that has a definite (constant) composition and distinct properties
• Mixture


  A combination of two or more substances in which the substances retain their distinct identities
• Homogeneous mixture


  A mixture in which the composition is the same throughout
• Heterogeneous mixture


  A mixture where the composition is not uniform
• Any mixture can be created and then separated by physical means into pure components without changing the identities of the components
• After separation, the components of the mixture will have the same composition and properties as they did to start with
• Element


  A substance that cannot be separated into simpler substances by chemical means
• Compound

  A substance composed of atoms of two or more elements chemically united in fixed proportions
• Compounds can be separated only by chemical means into their pure components
• States of substances

  • Solid
  • Liquid
  • Gas
• Physical property


  A property that can be measured and observed without changing the composition or identity of a substance
• Examples of physical properties

  • Color
  • Melting point
  • Boiling point
• Chemical property


  A characteristic of a substance that is observed during a reaction in which the chemical composition or identity of the substance is changed
• After a chemical change, the original chemical substance vanishes, and all that will be left is a different chemical substance
• Categories of measurable properties of matter

  • Extensive properties
  • Intensive properties
• Extensive property


  A property that depends on how much matter is being considered
• Examples of extensive properties

  • Mass
  • Length
  • Volume
• Intensive property


  A property that does not depend on how much matter is being considered
• A chemical reaction is a process in which a substance (or substances) is changed into one or more new substances
• Chemical equation


  A shorthand method of representing a chemical reaction using chemical symbols and formulas to indicate the reactants and the products
• Reactants


  The starting materials in a chemical reaction
• Products


  The substance formed as a result of a chemical reaction
• In a chemical equation, the reactants are conventionally written on the left and the products on the right of the arrow
• Chemists often indicate the physical states of the reactants and products using letters g for gas, l for liquid, s for solid, and aq for aqueous
• Knowing the states of the reactants and products is especially useful in the laboratory
• Every compound has a formula which cannot be altered
• A chemical reaction must account for every atom that is used
• This is an application of the Law of Conservation of Mass which states that in a chemical reaction atoms are neither created nor destroyed
• Completing and Balancing Chemical Equations

  1. Write correct formulas of reactants

  2. Decide type of reaction

  3. Write correct formula(s) for products

  4. Balance the equation
• Combination Reactions


  Two or more substances combine to form one product
• Decomposition Reaction


  A compound decomposes to form two or more substances
• Displacement Reaction

  A more active metal can displace a less active metal
• Less active metals cannot displace more active metals
• Types of reactions

  • Decomposition Reaction
  • Displacement Reaction
  • Metathesis (Double Displacement Reaction)
  • Neutralization Reaction
  • Combustion Reaction
• Decomposition Reaction


  1. Metal oxide + H2O + CO2

  2. Metal oxide + CO2

  3. Chloride + Oxygen

  4. Metal + oxygen

  5. H2 + O2
• Decomposition Reaction


  • 2 KHCO3 → Cu2CO3(s) + H2O(g) + CO2(g)
  • Mg(HCO3)2(s) → MgO(s) + H2O + CO2
  • Na2CO3(s) → Na2O(s) + CO2(g)
  • 2KCIO3(s) → 2KCI(l) + O2(g)
  • CaO(s) → Ca(s) + O2(g)
  • H2O(l) → H2(g) + O2(g)
• In a displacement reaction, a more active metal can displace a less active metal, while a less active one can’t displace the more active