Chemistry

What is Chemistry? The study of all substances and the changes they undergo. Called the central science because it overlaps many other sciences. Chemistry explains underlying reason things happen in our world.

Branches of Chemistry Organic – study of most carbon containing compounds Inorganic – study of non-organic substances, may have organic fragments bonded to metals Physical – study of properties, changes, and relationships between energy and matter Analytical – study of components and composition of materials Biochemistry – study of substances and processes occurring in living things Theoretical – use of math and computers to design and predict the properties of new compounds Give examples of each of the branches and some applications of each branch

Types of Chemical Research Basic Research – for the sake of increasing knowledge Applied Research – to solve a specific problem Technological Development – the production and use of products that improve our quality of life (lag behind discovery)

States of Matter Solid- fixed volume and shape Particles are in a rigid structure vibrating slightly in place high density Liquid- fixed volume but no fixed shape Particles move past each other Takes shape of container Allows liquid to flow Lower density Gas- no fixed volume or shape Expand to fit container Lots of space between particles Low density-also compressible Plasma Properties like gas Ionized gas More energy than gas

Properties Characteristics of matter Extensive properties depend on the amount of matter present mass, volume, energy Intensive properties do not depend on the amount of matter present melting point, boiling point, density

Other Categories of Properties Chemical –ability to undergo changes that transform it into different substances Examples: combustion (burn), oxidation (rust), corrosion, decomposition Physical- describe characteristics of that substance that can be measured or observed without changing the substance melting and boiling point, density, specific heat

Physical Changes Do NOT change the identity of the substance grinding, tearing, changing shape State changes are always physical changes Melting- solid to liquid Evaporation- liquid to gas Condensation- gas to liquid Sublimation- solid to gas Freezing- liquid to solid Deposition- gas to solid

Chemical Changes Change the identity of a substance Seen when 2 substances react to form a new substance Chemical equations describe chemical changes (chemical reactions) Ex – 2Na + Cl2 → 2NaCl Items on left are reactants (what you begin with) Items on right are products (what you end with)

Evidence of Chemical Change Formation of Gas Often you see gas, smoke, or bubbles Formation of precipitate You see a new solid in a liquid Release or absorption of heat or light You feel it get hot or cold Color changes Odor change

Evidence of Chemical Change