INTRODUCTION TO CHEMISTRY: Students will be able to understand; What is chemistry? States of matter Properties of matter Changes and mixtures

What is Chemistry?  The study of the composition of substances and the changes that substances undergo. (Addison-Wesley, 1993)  Contributes to other natural sciences such as biology, geology, and physics.  Subfields of chemistry: biochemistry, physical chemistry, organic and inorganic chemistry, and analytical chemistry.

Particle Theory Models help us understand complex ideas, such as how matter behaves. As new clues about matter have been discovered the models have improved. The basis for the particle model is the particle theory:  All matter is made up of small particles  Particles are always moving  Particles are held together by bonds that vary in strength  As particles are heated they move more quickly. When particles are cooled they move more slowly (kinetic molecular theory)

States of Matter  Matter: anything that takes up space and has mass ie golf ball vs. tennis ball Mass-amount of matter an object has  Solid: a definite shape and volume  Liquid: form of matter that flows, has a fixed volume and takes shape of a container  Gas: matter that takes both shape and volume of a container.

States of Matter:

Plasma-The 4 th State of Matter

Parts of Matter

Properties of Matter  Substance: a kind of matter that has a uniform and definite composition. Ie sugar vs lemon juice  Physical Property: quality or condition of a substance that can be observed or measured without altering its composition ie oxygen  color, solubility, mass, odor, hardness, density, electrical conductivity, melting and boiling points.

Changes and Mixtures  Mixtures: a physical blend of two or more substances. It is not pure because it can be made from more than one kind of matter.  Heterogeneous- not uniform in composition; different from another mixture ie. soil (silt, sand, clay)  Homogenous- completely uniform/same composition ie. toothpaste

Physical and Chemical Change  Physical change: alter of a substance without changing its composition (its state).  For example; leaving a block of chocolate in the sun causes the chocolate to melt and change STATE from a solid to a liquid. The chocolate is still chocolate. It can be cooled and turned back into a solid bar again.  Other examples of physical change include;  Cutting, grinding or bending  Temperature (melting, freezing, steam, vaporization, sublimation, condensation)  Break, bend, split, crack, crush, melt, boil  Ie crushing a can, melting an ice cube, and breaking a bottle.

Physical and Chemical Change  Chemical changes happen by combining a substance with another substance to produce a new substance.  Examples of chemical changes include combustion (burning), cooking an egg, rusting of an iron pan, and mixing hydrochloric acid and sodium hydroxide to make salt and water.  You can tell if a chemical reaction has occurred by Change of odor Change of color Change of temperature Formation of gases (bubbles) Formation of a precipitate (insoluble particles) Decomposition of organic matter (rotting food)