Transcript WHAT IS ENERGY?

Unit 2 Chemistry:
Matter and Energy
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Matter is made up of atoms and molecules
(groupings of atoms) and energy causes the
atoms and molecules to always be in motion either bumping into each other or vibrating
back and forth
The motion of atoms and molecules creates a
form of energy called heat or thermal energy
which is present in all matter. Even in the
coldest voids of space, matter still has a very
small but still measurable amount of heat
energy.
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Energy is defined as the ability to do work.
Work is defined as the distance a weight can be
pushed against some opposing force.
(example: how far a weight can be pushed up
against the force of gravity).
Therefore: energy is measure of how much far
a weight is lifted. Weight can be a large object
or as small as an electron.
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1.) Kinetic: The energy of MOTION. A rock
falling down a hill; an electron moving from
one place to another.
2). Potential Energy: The energy of position.
A rock on top of hill; energy stored in chemical
bonds.
3). NOTE: another term for THERMAL
ENERGY is heat.
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SEE THIS LINK:
http://fi.edu/guide/hughes/energytypes10.ht
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Kinetic: thermal, wind, sound, mechanical,
electrical, solar (light).
Potential: chemical, gravitational, nuclear,
springs, magnetic.
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http://glencoe.mcgrawhill.com/sites/dl/free/0078785337/160350/00076705.html
(All Forms)
http://glencoe.mcgrawhill.com/sites/dl/free/0078785337/161752/00035806.html
(Kinetic Energy)
http://glencoe.mcgrawhill.com/sites/dl/free/0078785337/160350/00035807.html
(Potential Energy)
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Take the quizzes at end of each movie!
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No, energy cannot be created OR destroyed.
The amount of energy in the universe is
constant.
Energy can change from one form to another.
EACH TIME ENERGY CHANGES FORM,
some heat is lost to the environment. This is
called nature’s heat tax.
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Temperature is a measure of the average
kinetic energy of particles. In other words,
how fast are the particles moving?
Heat is a bit more difficult to describe. Heat is
a form of light that is transferred BETWEEN
atoms or particles. Heat can be measured by a
thermometer if two separate objects are at
different temperatures.
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A thermometer is a SYSTEM that responds to
heat energy. Heat energy causes mercury atoms
or alcohol to move faster and expand. This
expansion is measured in the class column of a
thermometer.
Units for temperature are Celsius, Fahrenheit
and Kelvin, all named after the scientists who
invented them.
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Absolute zero occurs when all molecular motion
stops.
Fahrenheit and Celsius assumed ice cubes had no
motion.
Kelvin adjusted the scale so that temperature truly
starts at ZERO MOTION.
Why isn’t the Celsius and Fahrenheit scale the best
method for measuring temperature?
Temperature Conversion
Equations
°F = (1.8 x °C) +32
°C = (°F-32) x 0.555
Kelvin = °C + 273.2
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Two units for measuring energy are:
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calorie : calculated as the amount of heat required to
raise one gram of water up one degree Celsuis.
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Joule: The SI unit for heat. It requires 4.18 joules
heat to raise one gram of water up one degree
Celsius.
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The calories on a food label
aren’t the same as science
calories.
Calorie versus calorie:
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Food labels use Calorie which =
1,000 calories which = 1
kilocalorie:
 1 Calorie = 1,000 calories = 1
Kcal
Specific Heat Capacity Table
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A physical property of a pure
substance.
Measure of how much energy
is required to heat one gram
of a substance up 1 degree
Celsius.
Specific heat is assigned the
letter “c.”
The lower the heat capacity,
the faster a substance heats
up.
Specific Heat Capacity Table