Matter Physics
Physics ['fiz-iks] is the science of mechanics, motion, and matter.
What is matter?
What do you, your computer, and a CD-ROM have in common? They are all made of matter. The whole world, in fact, is composed of matter, material that everything is made of. Matter has mass and/or takes up space. All matter is composed of tiny pieces called particles. Matter is different depending on the particles and their properties. A property is a description.
The Four States of Matter
The state of matter is one important property. It tells the density or thickness of a kind of matter. It also tells how well the kind of matter, or substance, stays together. The four states of matter are solid, liquid, gas, and plasma.
At the lowest temperature possible, absolute zero (-460ºF or 0ºK), everything is solid. Solid substances are tightly held together by strong bonds. So solids, such as ice, keep their shape. The particles in solids are close together, so they can only vibrate, or move back and forth lightly. At absolute zero, particles are completely at rest. If the particles move faster, the solid would heat up. If the temperature gets high enough, the solid melts into a liquid. This temperature is called the freezing point or melting point. Helium has the lowest freezing point -- close to absolute zero. Water's freezing point is 32ºF (0ºC or 273ºK). Carbon has the highest melting point -- over 6,000 degrees Fahrenheit. If a solid and a liquid are mixed, it is called a semisolid ['sem-ee-sah-lid].
In a liquid, the particles can move around easily. They are loosely linked in liquids. A liquid takes the shape of the container it is in. So a liquid can assume many shapes. If the temperature gets high enough, the liquid will evaporate into a gas. Sometimes, the gas is trapped inside its liquid form as it evaporates and forms bubbles. In that case, the liquid boils. The temperature at which this happens is called the boiling point. The boiling point of water is 212ºF (100ºC or 373ºK).
After a liquid boils or evaporates, it becomes a gas. In a gas, the particles are widely spaced, so a gaseous substance can expand very far to fill the space it is in. Because the particles are spaced apart, gases have less density. Less-dense things float, so gases float above everything that is denser. Air that we breath is a mixture of gases, including oxygen and water vapor.
At a certain very high temperature around 5,000ºF (3,000ºK), particles lose bonds. They move so fast that they damage each other. This state of matter is called plasma. The particles in plasma are called nuclei.
Ice (Solid) Water (Liquid) Water Vapor (Gas) Sun (Plasma)
Other Properties
A substance has certain properties because its particles have those properties. So, an orange fruit is orange because it has particles that bounce back, or reflect, orange light. Rocks are hard because the particles are close together and have strong bonds. A black rock is black because its particles absorb most of the light shined on it, so it is dark. Plastic sticks to you because of static electricity because the particles are charged up.
Color
Things have colors when light is shined on them. Then light is bounced or reflected into your eyes. White objects can be any color because they reflect light. Black objects reflect little or no light, so they are dark. Light gets brighter when there is more of it or when it is condensed. Things have certain colors because of there kinds of particles.
Length
Length is one measurable property of an object. Length tells how long something is. One system of measurement is the metric system, in which meters and powers of ten are used. On the metric system, meters (m) are the basic unit of length, about the length of a baseball bat. Other units are the millimeter (mm) (.001 meter), the centimeter (cm) (.01 meter), and the decimeter (dm) (.1 meter). On a large scale, kilometers (km) (1,000 meters) are used to show distance. Different units, such as inches, feet, yards, and miles, are used in the U.S. customary system.
Volume and Capacity
Volume, another property, tells how much space an object takes up. The metric unit of volume is the cubic meter (m³ or cu m). An object with a volume of one cubic meter takes up as much space as a cube with a length of one meter. Other units of volume are the cubic centimeter and cubic decimeter. Cubic inches and feet are used in the customary system.
To find the volume, multiply the length by the width by the height. (2 meters x 2 meters x 6 meters = 24 cubic meters. Length x width x height = volume.)
Capacity tells the volume of a liquid or container. Capacity is measured with milliliters (mL) and liters (L). A thousand milliliters would equal one liter (mL x 1,000 = 1 x L). A bottle of soda is two liters. One cubic centimeter equals a milliliter.
Mass and Weight
Mass tells how much matter is in an object. In the metric system, grams (g) measure mass. A penny weighs about 3 grams. A milligram (mg) is a very small mass -- one thousandth of a gram (which is small itself). One thousand grams (2.2046 pounds) equals a kilogram (kg). Mass, in the customary sytem, is measured in ounces, pounds, and tons.
If you go into outer space, your mass will be the same, but your weight may vary. Weight tells how strongly gravity pulls on you. The more mass an object has, the more gravity needed to pull on it. So more mass means more weight. Weight is measured with newtons.
The mass of small gems is measured in carats. A carat is a very light mass. A penny weighs about 15 carats, so one carat is around 200 milligrams.
Density
Do you think that something is heavier when it is bigger? It is not always like that. Things that are the same size usually do not weigh the same. A balloon and a rock can be the same size, but the rock is heavier. The rock has more mass in a certain volume. The balloon has less mass, but takes up the same amount of volume. The rock is said to have more density.
Density tells how much mass is in a certain volume. Different objects and substances have different densities. If two objects have the same mass but one is bigger, the smaller one is denser because it has more mass in a small space.
Density is measured in grams per cubic meter (g/m³). Less-dense objects cannot hold objects that are more-dense. This is why objects with lower average densities than water float in water. Ice, cork, and air are less dense than water, so they float on top of water. The earth's core is nickel-iron and the crust is rock because nickel-iron is denser than rock.
Particles in low-density and high-density objects
Glossary
absolute zero [ab-suh-loot zee-roh] n. The lowest temperature possible at which particles are at rest; the temperature equal to -459.75ºF or 0ºK or -273.19ºC.
absorb [uhb-zawrb] v, absorbs, absorbed, absorbing To take in and trap (light).
air [ayr] n. A mixture of gases.
boiling point [boi-(uh-)ling point] n. The temperature at which a substance boils or evaporates; evaporation point; condensation point. Derivation: Point of boiling.
capacity [kuh-'pas-it-ee] n. The amount a container can hold; volume.
carat ['kar-ut] n. A unit of mass (used to measure small gems) equal to around 200 milligrams.
centimeter ['sen-tuh-mee-tur] n. A metric unit of mass equal to .01 meter (about .394 inch). Abbreviation: cm. Derivation: Centi- means hundredth.
cubic meter [kyoo-bik 'mee-tur] n, pl.cubic meters The basic metric unit of volume equal to the size of a cube one meter long. Abbreviation: cu m or m³. Derivation: Cubic means in the shape of a cube.
decimeter ['des-uh-mee-tur] n. A metric unit of length equal to .1 meter (3.94 inches). Derivation: Deci- means tenth.
density ['den-sit-ee] n, pl. densities The amount of matter packed into a certain space; thickness.
evaporate [ee-'vap-uh-rayt] v, evaporates, evaporating, evaporated To change from a solid or liquid to a gas. Derivation: Vapor is a gas.
expand [ik(s)-'spand] v, expands, expanding, expanded To increase in size and volume by decreasing density; grow. Derivation: Ex- means out.
freezing point ['freez-ing point] n. The temperature at which a liquid or gas cools and hardens into a solid; the freezing point of water (32ºF or 0ºC or 273ºK); melting point. Derivation: Point of freezing.
gas ['gas] n, pl. gasses, gases A low-density fluid substance that expands to fill the space it is in in which the particles are free and widely spaced; air.
gram [gram] n. The basic metric unit of mass equal to about the mass of a paper clip (.035 ounces).
gram per cubic meter [gram pur cyoo-bik 'mee-tur] n, pl. grams per cubic meter The basic metric unit of density, telling how many grams is in one cubic meter of a substance or object. Derivation: Gram in one cubic meter.
kilogram ['kil-uh-gram] n. A metric unit of mass equal to 1,000 grams (2.2046 pounds or 35.2736 ounces). Derivation: Kilo- means thousand. Kilo- is the basis of our abbreviation of thousand -- K.
kilometer ['kil-uh-mee-tur] n. A metric unit of length and distance equal to 1,000 meters (.621 mile or 1,093 yards, 1 foot, and 9.6 inches. Derivation: Kilo- means thousand. Kilo- is the basis of our abbreviation of thousand -- K.
length [length] n. The distance from one end of an object to the other end.
liquid ['lik-wid] n. A fluid substance with loosely-linked particles that takes the shape of its container.
liter ['lee-tur] n. The basic metric unit of capacity or volume equal to a cubic decimeter (61.02 cubic inches) .908 dry quarts or 1.057 liquid quarts -- half of a regular bottle of soda.
mass [mas] n. The amount of matter in an object; matter.
matter ['mat-ur] n. The material that makes up everything; anything that has mass and takes up space; material; stuff; mass; substance.
melting point ['mel-ting point] n. The temperature at which a solid changes or melts into a liquid; the melting point of water ice (32ºF or 273.15ºK or 0ºC); freezing point. Derivation: Point of melting.
meter ['mee-tur] n. The basic metric unit of length equal to 39.37 inches or 1.0936 yards.
metric system ['met-rik sis-tum] n. The system of measurement that uses meters to measure length and is based on units and their powers of 10.
milligram ['mil-uh-gram] n. A metric unit of mass equal to .001 gram (about .0000343 ounce). Derivation: Milli- means thousandth.
newton ['n(y)oo-tun] n. A unit of force equal to the force needed to make one kilogram of mass move at one meter per second. Derivation: Isaac Newton.
particle ['pahr-tik-ul] n. A tiny piece of matter; molecule; atom.
plasma ['plaz-muh] n. A substance in which the temperature is so high that the particles (atoms) are decomposed into nuclei.
property ['prah-pur-tee] n, pl. properties Something that describes an object; uniqueness; description.
reflect [ree-'flekt or ruh-'flekt] v, reflects, reflecting, reflected To bounce away (light); reject. Derivation: Re- means again.
semisolid ['sem-ee-sah-lid] n. A mixture or an object with properties of both solids and liquids. Derivation: Semi- means half.
solid ['sah-lid] n. A substance with particles that are bonded together and keeps its shape.
state [stayt] n. A state of a substance with certain properties: the relation of particles, shape, density, and required temperature of a substance; one of the four states of matter: solid, liquid, gas, or plasma; quality; property.
substance ['sub-stuns] n. A certain kind of matter; an element or compound; chemical; object; matter; stuff; material; thing.
volume ['vahl-yoom] n. The amount of space an object takes up; the amount of cubic units needed to fill an object if it was hollow; capacity.
weight [wayt] n. The force of a mass pressing down on the surface of a mass with gravity because of gravity.