Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc. ALL RIGHTS RESERVED. Chapter 2

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc. ALL RIGHTS RESERVED.

Matter and Energy

Chapter 2


Atoms

Matter Substance that

occupies space Substance that has

mass Mass—measure of

the amount of atoms All matter is made up

of atoms Possess unique

physical and chemical properties


Atoms (continued)

Three subatomic particles: Protons Electrons Neutrons

Protons and neutrons form the nucleus

Electrons revolve around the nucleus

Bohr model is the most popular model


Atoms (continued)


The Elements

Protons—subatomic particle (+) charge

Electrons—subatomic particle (–) charge

Neutron—subatomic particle with no electrical charge

Atomic number helps to classify atoms Atoms are also known as

elements Over 109 different atoms or

elements


States of Matter

Four states: Solids – Liquids Gases – Plasma

Atoms in solids are tightly packed

Atoms in solids are restricted in movement

Atoms are in a crystal pattern

Matter in solid state has a definite shape


Molecules of a Solid


States of Matter (continued)

Liquids are composed of atoms that are more loosely arranged

Atoms have more freedom of movement

Liquids have no definite shape

Atoms are arranged in long chains or clumps

Movement of atoms is less restrictive


Molecules of a Liquid



When a solid turns into a liquid Refers to change in state or

phase change Phase changes depend

on certain temperature and pressure

Temperature of change: from solid to liquid called

melting point from liquid to solid called

freezing



Atoms in a gas: Highest degree of

movement Undergo constant collisions

with other atoms Gas has no definite shape Collisions with walls of a

solid container Causes pressure More collisions the higher

the pressure


Molecules of a Gas



Liquid changes phase to a gas— vaporization

Temperature to change a liquid to a gas—boiling point

Change of a gas to a liquid—condensation

Solid directly into a gas—sublimation



Plasma Atoms of gas are exposed to high energy Atoms begin to ionize and lose electrons This creates a high-energy fluid gas mixture

composed of ions and electrons Stars are composed of plasma


Compounds and Molecules

109 different atoms make up Earth’s elements

Chemically joined atoms are called compounds

Compounds are referred to as molecules

More than 10 million compounds exist

Two substances mixed are called a mixture


Energy

Relationship between matter and energy Fundamental cause for

existence Albert Einstein

Energy and mass have a mutual relationship

E = mc2

Ability to do work or cause change

Motion when matter is exposed to energy


Energy (continued)

Two basic forms: Kinetic

Energy of motion Movement of Earth around the Sun

Potential Stored energy Gasoline in the tank of your car


Law of the Conservation of Energy

Energy cannot be created or destroyed Energy only changes form Energy changes from one form to another

No real gain or loss Forms of energy:

mechanical – gravitational – radiant thermal – electrical –

magnetic nuclear – chemical


Electromagnetic Radiation

Kinetic energy of movement or vibration Travels in the form of a wave

The higher the electromagnetic radiation, the shorter the wavelengths

The lower the electromagnetic radiation, the longer the wavelengths

Electromagnetic spectrum: Energy and wavelength of different forms


Electromagnetic Radiation (continued)

Gamma rays—highest energy waves Wavelength 1 billionth of a centimeter

Radio waves—lowest energy waves Wavelength as large as 10 kilometers

Electromagnetic waves travel at the speed of light: 186,000 miles per second


Electromagnetic Radiation (continued)

Electromagnetic energy interacts with matter: Refraction—waves change direction and bend Reflection—waves bounce off substances Scattering—waves refracted or reflected Absorbed—wave’s energy is taken in Transmission—waves pass through matter


Energy Transfer

Three fundamental processes: Conduction—transfer by direct contact Radiation—movement in an empty space Convection—circular movement of heat

In gas or liquid Caused by differences in temperature & humidity


Heat and Temperature

Temperature—substance’s average kinetic energy

Higher temperature, more motion of atoms

Temperature measured on three scales: Fahrenheit Celsius Kelvin


Heat and Temperature (continued)

Fahrenheit and Celsius Freezing point—32°F and 0°C Boiling point—212°F and 100°C

Kelvin—measures average kinetic energy 0°K—all particles stop motion

Temperature never reached on Earth Based on absolute zero

0°K = -459.67°F and -273.16°C



Heat—measure of flow of kinetic energy Total kinetic energy in a system Flows from high to low kinetic energy

Called a sink Calorie = energy to raise 1 gram H2O 1°C Specific heat

Heat to raise 1 gm of a substance 1°C Also called heat capacity



Latent heat of condensation Water vapor to a liquid

1 gram water vapor into liquid 840 calories released

Liquid water to a solid—80 calories released Latent heat of vaporization

Liquid water vaporizes into water vapor 840 calories absorbed

Documents

Copyright © 2008 Thomson Delmar Learning, a division of Thomson Learning, Inc. ALL RIGHTS RESERVED. Chapter 2