MATTER AND ENERGY

CHEMISTRY The study of the composition and changes that matter undergoes Changes may be: 1.physical 2.chemical 3.nuclear

Branches of Chemistry OrganicInorganic PhysicalAnalytical BiochemistryTheoretical

Chemical  Any substance that has a definite composition.

Matter 1.Anything that has mass 2.Takes up space

Mass  Measure of the amount of matter.  Measured in grams using a balance.

Weight  Measure of the gravitational force exerted on an object.  Measured in Newtons using a scale.

Basic Building Blocks of Matter 1.atom 2.element 3.compound

States of Matter

Properties of Matter May be: 1.Physical-These may be measured or observed without changing the identity of the substance 2.Chemical- these describe the substance's ability to undergo changes that transform it into different substances

Changes in matter 1.Physical changes-do not involve a change in the identity of the substance. 2.Chemical changes - Two or more substances are converted into different substances.

Chemical Change REACTANTS PRODUCTS

EVIDENCE OF A CHEMICAL REACTION 1.Change in color 2.Change in Odor 3.Change in energy 4.Formation of a precipitate 5.Effervescence 6.Evolution of heat or light

Extensive Properties  Depend on the amount of matter present.  Examples are volume, mass, amount of energy in a substance.

Intensive properties  DO NOT depend on the amount of matter present.  Examples are melting point, boiling point, density, electrical conductivity.

ENERGY The ability to do work. Measured in Joules (J)

Forms of Energy

Changes in Energy Endothermic

Entropy  The number of possible ways that the energy of a system can be disturbed. (The measure of disorder of a system.)  Represented by the symbol S

Entropy

1.Entropy of a gas is greater than that of solids or liquids. 2.Entropy increases in a chemical rxn when the total number of product molecules is greater than the total number of reactant molecules. 3.Entropy increases with a temperature increase.

 2 nd Law of Thermodynamics- Spontaneous processes always proceed in such a way that the entropy of the universe increases.  A spontaneous process is any physical or chemical change that once begun, occurs with no outside intervention.

Processes in Nature  Processes in nature are driven toward the lowest energy and the highest entropy.

Law of Conservation of Matter and Energy Matter/Energy can neither be created nor destroyed. The mass of the reactants = the mass of the products. Einstein's equation shows that matter and energy can be interconverted and supports the Law of Conservation of Matter and Energy. E = mc 2 This law was proposed by Antoine Laurent Lavoisier.

Classes of Elements 1.Metals 2.Nonmetals 3.Metalloids 4.Noble Gases