Matter is anything which has mass and takes up space. Mass is the amount of matter something contains. At sea level on earth, mass and weight are the same thing. Matter is classified according to shared characteristics. One way that scientists classify matter is: Solids, liquids, gas, plasma. These are the states of matter. 1. Solids have a definite share, and they are difficult to penetrate. Examples of solids are wood, plastic, iron, copper, gold, and lead.
2. Liquids do not have a definite shape, but take on the shape of the container that they are in. Examples of liquids are water, alcohol, gasoline, vinegar, milk, and orange juice.
3. Gases have no definite shape and no definite volume. Gases tend to fill whatever space is available. Examples of gases are hydrogen, helium, oxygen, nitrogen, carbon dioxide, carbon monoxide, and ozone.
4. plasma exists only in extremely high temperatures, such as
inside of stars like our sun. It is the product of nuclear fusion
and is similar to a gas.
One big problem with classifying matter as solids, liquids or gases
is that most matter can change from one state to another. For
example water can be a liquid, a solid when it is frozen to form
ice, or a gas such as the water vapor which forms clouds. Carbon
dioxide can be a gas, a liquid, or it can be frozen solid to form
dry ice. Oil is generally a liquid, but it can be made solid such
as when it is turned into plastic. Mercury is a liquid metal at
room temperature, but becomes a solid when cooled. So matter can
often change in form when the temperature is changed. Ordinarily
when a solid is heated, it goes from a solid to a liquid to a gas.
However, some matter, such as carbon dioxide will sublimate , or
skip a state. When dry ice is heated it does not become a liquid
but goes from the solid state to a gas. Great pressure is required
to make carbon dioxide become a liquid.
Another way to classify matter is as metals or non-metals.
1. Metals have these characteristics:
a. They can be polished to be made shiny.
b. They are ductile. Ductile means that they can be made into wires.
c. They are usually good conductors of heat and electricity.
Examples of metals are copper, iron, tin, aluminum, silver, gold, lead, mercury, and chromium.
2. Non-metals have these characteristics:
a. They are usually not shiny (glass and plastic are exceptions)
b. They are usually not ductile
c. They are usually poor conductors of heat and electricity
Another way to classify matter is as elements, compounds and mixtures.
1. An element is matter composed of only one kind of atom. The atom is generally thought of as being the smallest unit of matter.
Examples of elements are oxygen, gold, iodine, uranium, silver, carbon, helium, hydrogen, sodium, and chlorine. There are 92 known naturally occurring elements, plus several which are man-made.
The elements have abbreviations. Some of these are:
H=hydrogen He=helium C=carbon N=nitrogen O=oxygen
Na=sodium Mg=magnesium K=potassium Ca=calcium Fe=iron
Co=cobalt Zn=zinc As-arsenic Au=gold Hg=mercury Cu=copper
Pb=lead Ag=silver Li=lithium U=uranium Cl=chlorine
Al=aluminum Si=silicon I=iodine Ne=neon Ni=nickel
2. Compounds are matter composed of two or more elements which are chemically bonded together. Examples of compounds are: H2O=water
H2O2=hydrogen peroxide CO2=carbon dioxide CH2=methane
NH3=Ammonia CO=carbon monoxide NaCl=salt
3. Mixtures are matter composed of two or more substances which are
not chemically bonded together. Examples: air is a mixture of
nitrogen, oxygen, carbon dioxide, and other substances. A mixture
of two or more metals is called an alloy. Brass is an alloy of
copper and zinc. Stainless steel is an alloy of chromium,
manganese and iron.
The difference between a compound and a mixture is that in a
compound the elements are chemically bonded together and in a
mixture they are not chemically bonded together.
The word "dissolve" means to form a solution. When the substances which compose a mixture are spread evenly throughout each other the mixture is called a solution. So a solution is a special kind of mixture in which the substances are spread evenly throughout each other. Sand and water will make a mixture, but they do not form a solution because the sand never dissolves in the water. However, sugar and water form a solution because the sugar does dissolve in water. Salt also forms a solution with water. For two substances to form a solution, one must dissolve in the other.
1. Solute--the substance which dissolves. Examples: sugar or salt
2. Solvent--the substance which does the dissolving. Water is the
most common solvent. More things dissolve in water than in any
other solvent. When water is mixed with an acid such as
hydrochloric acid (HCl) it can dissolve more things. Hydrochloric
acid is stomach acid which dissolves food in digestion. When
carbonic acid becomes dissolved in water, it forms a type of acid
rain which can dissolve underground pockets of limestone. When the
limestone dissolves, the ground above might suddenly collapse to
form a sink hole. If water is mixed with a base, it also can
dissolve many things.
Some common solutions: coffee, colas, and carbonated water.
Carbonated water is a solution composed of carbon dioxide gas
dissolved in water.
Solutions are classified according to how much solute they contain:
1. saturated solution--contains the maximum amount of solute that will dissolve in the solvent.
2. unsaturated solution--contains less than the maximum amount of solute that will dissolve in the solvent.
Matter can change in two ways:
1. physical change--change in the properties of a substance without a change in the substance itself. Examples of physical changes are: 1. water freezing, thawing, or forming water vapor. 2. gases expanding when heated and contracting when cooled. The most common physical changes are the changes in phase or state. These occur when a substance changes from a solid to a liquid to a gas. The physical change of phase occurs due to changes in temperature. For example:
a. water freezes solid at temperatures below 32 degrees Fahrenheit or zero degrees Celsius, becomes a liquid at higher temperatures, and forms a gas vapor at temperatures over 212 degrees Fahrenheit or 100 degrees Celsius.
b. lead (Pb) melts to form a liquid at 327 degrees Celsius
c. copper (Cu) melts to form a liquid at 1083 degrees Celsius
d. sodium (Na) melts at 98 degrees Celsius and vaporizes into a gas at 883 degrees Celsius
e. the physical change from a liquid to a gas is called evaporation. The bubbles seen when something boils is the gas escaping from the liquid.
f. condensation is the physical change from a gas to a liquid.
Condensation occurs when the temperature is cooled. An example is when water forms on the outside of a cold drink can or on the windows of an air conditioned room.
2. a chemical change is a change which produces a new substance.
Burning produces a chemical change. When gasoline burns it changes
from gasoline to water and carbon dioxide. Iron rusting is another
example of a chemical change. When iron rusts it changes from iron
to a substance called iron oxide (rust). Frying an egg changes the
chemical structure of the egg protein.
In a chemical change the volume of the substance may change but the
mass does not. This is called the Law of Conservation of Matter.
This law states that in a chemical change, mass is not gained or
lost. If you burned a block of wood and could collect the ashes
and vapors which this burning produced, their mass would be the
same as the original block of wood. If you burned paper and
collected the vapors and ashes, the mass would be the same as the
original paper. Another way to put the Law of Conservation of Mass
is that matter cannot be created or destroyed, but can only be
changed in form. Burning (combustion) is a common way of creating
a chemical change.