Chapter 1: Introduction to Chemistry

What is chemistry? Study of stuff Study of the composition of substances and the changes they undergo

Chemists: Solve problems dealing w/ the ingredients the world is made of Looks at how it behaves and how it is put together

Research Types: Pure Research- seeks to gain knowledge for the sake of knowledge itself Applied Research- research undertaken to solve a specific problem

Scientific Method Logical approach to solving problems dealing with the “stuff” the world is made of Uses evidence

Steps to the Scientific Method 1.Ask a question/ ID the problem 2.Observe and infer 3.Hypothesis- proposition based on certain assumptions (can be evaluated scientifically), educated guess

4. Experiment Control/constants/variable -Independent Variable-variable that you change -Dependent variable- variable that changes due to the independent variable changing

4. (cont) Ex. Pressure on a balloon -Increase pressure decreases volume -Independent-pressure, dependent- volume

4. (cont) Collect data -Qualitative Data- describes a property w/out measurements, uses senses (ex. Color) -Quantitative data – data collected using measurements (ex. Volume)

5. Conclusion Refers to hypothesis Support with evidence found in experiment Use Models (develop in mind or physically to help deal with abstract ideas or objects that are too big, too small or too complicated)

Ingredients of Chemistry:

1. Matter Stuff, everything Has the property of inertia Takes up space, has mass

a. Inertia Resistance to change in motion or resistance to change in direction or rate

b. Mass Amount of matter in an object Measure of the inertia Does NOT change from place to place Measure with a balance

c. Weight Measure of the force of gravity between 2 objects Weight= mass X gravity Changes with location Measure with scale

2. Energy Property possessed by matter, ability to do work We are interested in the energy changes that take place

Types of Energy Potential- energy due to the objects position, also stored energy (ex. Battery- chemical potential energy) Kinetic- energy of motion Radiant- energy that goes in all directions (light, x-rays, UV), transferred by electromagnetic waves Other- heat, sound, nuclear, electric

Rules Chemists Follow:

Theory -statement that gives a tentative explanation based on supported hypotheses Ex. Atomic Theory

Law - describes something that is known to happen without error, but doesn’t explain how it happens Ex. Laws of Gravity, Laws of Motion

Law of Conservation of Mass Total amount of matter in the universe remains constant Matter can’t be created nor destroyed Total amount b/4 reaction= total amount after reaction

Law of Conservation of Energy Energy can’t be created nor destroyed Total amount remains constant Can transform into different types of energy Ex. Match: potential chemical energy into heat, light, sound, kinetic

Chapter Practice staffweb/smith/Nancy/chemistry/ch emistry%20homework.htm