I Chemistry

B. Scientific Method- a set of general principles used by scientists to study the world 1. Observation - observations based on measurements are called data 2. Hypothesis - a testable interpretation of the observations 3. Experiments - tests that help determine the validity of a hypothesis - results of experiments can support or falsify a hypothesis but they cannot prove it to be true 4. Theory - a hypothesis that has been supported by many experiments - a theory continues to be tested with new experiments and may be modified or even replaced

Chapters 1 & 3 Matter and Energy

A. Definition- The study of the structure, properties and reactions of matter.

II Law of Conservation of Matter and Energy- Matter and Energy can’t be created or destroyed, it just changes form

- (E=mc2) - Einstein

- the ability to do work or transfer heat. A. Potential Energy (stored energy) -the energy a body possesses by virtue of its position or composition

B. Kinetic Energy ( energy of motion) - the energy a body possesses while in motion or transferring heat.

III Energy

A. Physical -Can be observed without changing the identity of the substance

-ex. Mass, Volume, texture, temperature, density, color B. Chemical

- Depends on how a substance reacts with other substances - Changes the identity of the substance - ex. Flammability, acidity, reactivity

IV Properties of Matter

V ChangesA. Physical

- No new substance is formed

- Reversal of the process results in the original substance

- ex. dissolving, phase changes, conductivity, magnetism

B. Chemical Change (reaction)

- A new substance is formed

- involves a new arrangement of atoms, no new atoms are formed

- all biological functions are chemical changes

1. Evidence of a chemical change A. Release of a gas (fizzing)

B. Color change

C. Precipitate

- an insoluble solid formed from two solutions

D. Energy released or absorbed

2. Two Types of Chemical Reactions

A. Endothermic

- Absorbs energy

- Usually feels cold

- Products contain more energy than reactantsTime

- Usually not spontaneous

- More energy is required to break the bonds of the

reactants than is released when product is formed

B. Exothermic

- Releases energy

- Usually feels hot

- Reactants contain more energy than products

- Usually spontaneous

- Less energy is required to break bonds of reactants than is

released when product is formed

Time

Activation Energy (Ae)- the energy required to break the bonds that initiates the reaction

3. Reaction Tendencies- 2 forces in natureA. All matter seeks its lowest energy stateB. All matter seeks its highest entropy (disorder)

4. Ways to increase the Rate of Reaction 1. Add energy (heat, light, electricity, stir) 2. Increase Surface Area 3. Dissolve in water 4. Catalyst – speeds up reaction rate without being used up

- lowers the activation energy - enzymes – biological catalysts

VII Classification of Matter Matter – anything that has mass and takes up space

A. Element-smallest unit of a substance that maintains its own unique properties-examples: periodic tableB. Compound

-Chemical combination of two or more elements -ex. Water (H20), CO2, salt (NaCl), sugar (C6H12O6)

C. Mixture -Physical combination of two or more substances each of which maintains its own unique properties and can be separated by physical means

1. Homogeneous – composition is the same throughout2. Heterogeneous – composition is not uniform

Classify the following as A) physical or B) chemical changes.1___ melting ice2___ chopping wood3___ burning paper4___ dissolving salt in water5___ digesting food6___ boiling water7___ forming clouds 8___ healing a wound

Classify the following as A) Observation B) Hypothesis C) Experiment D) Theory9___ The sun is bright10___ Dropping two objects from the same height to see if they fall at the same speed.11___ An unknown substance is shiny so we believe it will conduct an electric current.12___ An unknown substance is flammable13___ Based on numerous experiments we believe that all matter is made up of atoms

Classify the following as A) endothermic or B) exothermic changes.14___ burning charcoal15___ melting ice16___ exploding a firecracker17___ using a chemical ice pack18___ boiling water

Classify the following as A) Potential, or B) Kinetic Energy19___ Energy stored in the sugar molecule20___ A mill wheel being turned by a running stream21___ An exploding firecracker22___ A ball at the top of a hill

Classify the following as A) element, B) compound or C) mixture23___ copper24___ chocolate chip cookie25___ water26___ sugarClassify the following as A) heterogeneous or B) homogenous mixtures27___ salt water28___ people29___ rock