Chapter 2: Energy & Matter
Name the three basic forms of energy
State the law of conservation of energy
Compare the Fahrenheit, Celsius, and Kelvin temperature scales
Explain what is meant by absolute zero
Name and describe the four states of matter
Compare the physical and chemical properties of matter
State the law of conservation of matter
2-4 Elements and Compounds
Explain the difference between an element and a compound
Compare heterogeneous and homogeneous mixtures
Describe several techniques to separate mixtures
Energy = the capacity to do work or to produce heat. What are different forms of energy? (TPS)
Look around the room and identify as many as possible with your partner. Set book near edge of
table and knock it off. To demonstrate potential energy. Ask students to write all the forms of
energy they can think of in their notebook after brainstorming.
Energy comes in many forms but can be classified into three broad categories:
1. Kinetic- energy of motion (including thermal)
2. Potential- stored energy, possessed by objects because of their position or the arrangement
of their particles
3. Radiant energy- i.e. sunlight
1. A common unit is the calorie. One cal is the amount of energy required to raise one gram of
water one degree Celsius. (1 cal = 1g x 1 degree C)
2. The Calorie (uppercase C), found on nutritional labels, is the same as 1000 cal or 1
3. The SI unit is the joule (J). 1cal = 4.184 joule. Discovered by James Joule. The results of his
experiments are summarized in a natural law known as the law of conservation of energy
4. Law of conservation of energy- In any process energy is neither created or destroyed
Do sample problem #1 p. 58
Do sample problems:
3.5 x 10 (6th) cal = ? joules 1.5 x 10 (7th)
105 J = ? Cal
47500 cal = ? J
2-1 Review and reinforcement
Review Kinetic and potential energyy
Thermometer used to measure temp.
Gabriel Fahrenheit (1686-1736) made especially good thermometers. He devised his own
Different scale was adopted by scientists for temp. measurements called Celsius scale named after
Swedish astronomer named Anders Celsius (1701-1744). It is more compatible w/ metric system.
o Freezing point of pure water at sea level is 0 degrees and the boiling point of pure water is
o Figure 2-9 compares the 2 scales (p.62)
Third scale is part of the International System of Units (SI). It is called the Kelvin Scale named
after William Thompson, Lord Kelvin.
o Unit of temp is the Kelvin.
o Degree symbol is not used
o Kelvin is the same size as the Celsius degree
o The difference is that the Kelvin has a different 0 point. Absolute 0 = -273 degrees Celsius.
Absolute 0 is the point at which the motion of particles of matter (kinetic energy) ceases.
Sample problem 2 on board
Work practice problems 3 & 4 in notebook
Work alt sample problems 2, 3 & 4 in notebook.
Home work 2-2 Practice & reinforce
Matter is anything that has mass and takes up volume…even air.
States of Matter
1. Solid- has shape & volume. High density
2. Liquid- volume but no shape. Assumes shape of container. High density
3. Gas- no definite shape or volume. It expands to fill the available volume of its container. Low density
(depends upon pressure)
4. Plasma- exists at extremely high temperature. Low density
You can change the state of matter by heating or cooling (altering amount of energy). This can cause
it to go from one state to another.
Physical properties- characteristics of a substance that can be observed w/o altering the identity of the
substance, ie> density, color & melting point
Chemical properties- characteristics of a substance that cannot be observed w/o physically altering it,
Physical change- identity of substance does not change ie> heat, melt, freeze, crush, tear
Chemical change- alter the identity of the substance, ie> burning, rusting
Conservation of Matter
Law of Conservation of Matter- Like energy, matter is neither created or destroyed.
Proven by Antoine Lavosier, “father of modern chemistry”, Frenchmen (1743-1794). Proved Law of
Conservation of Energy by burning a candle under glass on a balance. He insisted upon precise tools
for accurate & precise measurements. He was beheaded during the Reign of Terror that followed the
Homework 2-3 Practice Problems & Review
2-4 Elements & Compounds
An Element is a substance that cannot be separated into simpler substances by a chemical change
Everything then is made up of elements
Elements are listed on the periodic table
sometimes common name, ie> H, He
sometimes Latin name, ie> Na= sodium/natrium Au= gold/aurum
A Compound is two or more elements combined in a chemical reaction.
A compound is a substance that contains two or more elements combined in a fixed proportion
Have a new set of properties, ie> H2O is the same anywhere you go
Distinguishing between Elements & Compounds
Elements and compounds are both pure substances- they have a unique set of physical & chemical
Electrolysis- a technique can tear apart some compounds w/ electricity but not elements
Visual- Paper clips hooked and unhookedl
2-5 Mixtures- can be separated into two or more pure substances
1. Heterogeneous- visibly different parts ie> some salad dressings, chocolate chip cookies, what other
2. Homogeneous- no visibly different parts. Ie> air, seawater, other examples?
Separating mixtures- kinds that do not cause chemical changes include:
1. filtration- used to separate heterogeneous mixtures by passing through a filter
2. Distillation- used to separate homogeneous mixtures. Can be used to separate solid impurities from
liquids- take advantage of different boiling points, lower boiling point changes into gas first
3. Crystallization- used for homogeneous mixtures. Can be used through evaporation
4. Chromatography- used for homogeneous mixtures. Separated by flowing along a stationary substance.
Ie> ink through paper separates by color, some are held by while others move ahead. Pattern of colors
shows separated pigments.
Mix dye with water. Pour through paper filter. Is mixture homogeneous or heterogeneous?
Changes in matter are always accompanied by changes in energy.