Changing States of Matter

Elements and compounds can move from one physical state to another and not change their basic atomic

parts. Oxygen (O₂) as a gas still has the same properties as liquid oxygen. The liquid state is colder and denser, but the molecules (the basic parts) are still the same. Water (H₂O) is another example. A water molecule is made up of two hydrogen (H) atoms and one oxygen (O) atom. It has the same molecular structure whether it is a gas, liquid, or solid. Although its physical state may change, its chemical state remains the same.

So you're asking, "What is a chemical change?" Let's start with a glass of pure water. If the formula of water were to change, that would be a chemical change. If you could just add a second oxygen atom, you would have hydrogen peroxide (H₂O₂). The molecules in your glass would not be water anymore. A chemical change happens when the atoms in a molecule are moved around or when atoms are added or taken away. Chemical changes happen when bonds between atoms are created or destroyed. Changing physical states of matter is about changing densities, pressures, temperatures, and other physical properties. The basic chemical structure does not change when there is a physical change.

TYPES OF MATTER: MIXTURES

Mixture Basics Mixtures are absolutely everywhere you look. Most things in nature are mixtures. Look at rocks, the ocean, or even the atmosphere. They are all mixtures, and mixtures are about physical properties, not chemical ones. That statement means the individual molecules enjoy being near each other, but their fundamental chemical structure does not change when they enter the mixture. If the chemical structure changed, it would be called a reaction. When you see distilled water (H2O), it's a pure substance. That means that there are only water molecules in the liquid. A mixture would be a glass of water with other things dissolved inside, maybe one of those powders you take if you get sick. Each of the substances in that glass keeps its own chemical properties. So, if you have some dissolved substances in water, you can boil off the water and still have those dissolved substances left over. If you have some salt (NaCl) in water and then boil off the water, the salt remains in the pan. The salt is left because it takes very high temperatures to melt salt (even more to boil it). Mixtures are Everywhere

There are an infinite number of mixtures. Anything you can combine is a mixture. Think of everything you eat. Just think about how many cakes there are. Each of those cakes is made up of a different mixture of

ingredients. Even the wood in your pencil is considered a mixture. There is the basic cellulose of the wood, but there are also thousands of other compounds in that pencil. Solutions are also mixtures, but all of the molecules are evenly spread out through the system. They are called homogenous mixtures.

If you put sand into a glass of water, it is considered to be a mixture. You can always tell a mixture, because each of the substances can be separated from the group in different physical ways. You can always get the sand out of the water by filtering the water away. If you were busy, you could just leave the sand and water mixture alone for a few minutes. Sometimes mixtures separate on their own. When you come back, you will find that all of the sand has sunk to the bottom. Gravity was helping you with the separation. Don't forget that a mixture can also be made of two liquids. Even something as simple as oil and water is a mixture.

Alloys

There are a few more words you might hear when people talk about mixtures. We can't cover all of them, but

we'll give you a quick overview of the biggies. Alloys are basically a mixture of two or more metals. Don't forget that there are many elements on the periodic table. Elements like calcium (Ca) and potassium (K) are considered metals. Of course, there are also metals like silver (Ag) and gold (Au). You can also have alloys that include small amounts of non-metallic elements like carbon (C). Metals are the key thing to remember for alloys.

The main idea with alloys is that the combinations work better together than any of the metals do alone. Metallurgists (people who work with metals) sometimes add chromium (Cr) and/or nickel (Ni) to steel. While steel is already an alloy that is a very strong metal, the addition of small amounts of the other metals help steel resist rusting. Depending on what element is added, you could create Stainless Steel or Galvanized Steel. It's always about improving specific qualities of the original. Another good example of an alloy happens when metallurgists add carbon to steel. A tiny amount of carbon (a non-metallic element) makes steel stronger. These special carbon-steel alloys are used in armor plating and weapons. 

AN EXPERIMENT!!!!!!!

DOES AN EGG FLOAT OR SINK IN WATER?
We will try to answer this question in the classroom.
What do you think?

THE PROPERTIES OF MATTER

History tells us that Archimedes (287 - 212 B.C.), a Greek mathematician and inventor, was given the task by King Hieron of determining whether the King's newest crown was made of pure gold. The King suspected it was not, but he could not allow Archimedes to scratch or damage the crown in any way. It was a complex task for Archimedes until he realized that when the crown was immersed in water, the volume of water that overflowed would be equal to the volume of the crown. This information, together with the weight of the crown, enabled him to determine the density of pure gold and compare it with the density of the metal in the crown. Not all went well for the crown maker, since it turned out that the crown was made from a metal less dense than pure gold. In this way one of the first practical applications of density was born.
Every substance has it own unique value for density. Density measures the amount of mass in a single unit of volume. A lead block has more mass than the same volume of aluminum. We thus say that the density of lead is greater than aluminum. Density also applies to liquids. If we wanted the same mass of water and rubbing alcohol, we would need a greater volume of alcohol because it is less dense than water.
The density of any material can be determined by dividing the mass by the volume. We can write this as a formula:
Density = Mass / Volume

Mass and Volume Labs

Calculating Densities (1)

		This lab shows a method for determining mass and volume of an object based on displacement of water by the object.

Calculating Densities (2)

		This lab demonstrates a method of discerning metals on the basis of density, by calculating the mass and volume of two metal cubes.

Calculating Densities of Solids

		This lab illustrates a method of determining the density of an unknown metal by calculating mass and volume.

Comparing Densities of Liquids

		This lab provides a method for comparing the mass of two liquids to determine which is greater.

Comparing Densities of Solids

		This lab provides a method for comparing the mass of lead and gold, and determining whether a substance is one or the other.

Finding the Mass of an Object

		This lab shows a method for determining the mass of an object suspended in a liquid.

Identification by Density

		This lab demonstrates a method for determining a substance based on comparisons of mass and volume.

Weight and Density

		This lab explains a method of determining a substance based on density.

 

What is matter?

Everything that has weight and occupies space is called matter. All matter is made from particles called atoms and molecules. This matter can be classified into three states. Learn more about matter and its three different states with the help of this animated learning module. 

                                                                                                        

                                                                                                       

SONG ABOUT MATTER

SCHEME OF THE UNIT CONTENTS

MATTER

1- MATTER AND ITS PROPERTIES
    1.1- Matter-substance-atoms
    1.2- General properties of matter
         . mass
         . volume
         . temperature
    1.3- Specific properties of matter
         .colour
         . hardness
         . density float/sink

2- TYPES OF MATTER
    2.1- Pure substances and MIXTURES
        2.1.1. Heterogeneous mixtures
        2.1.2. Homogeneous mixtures or solutions
                      .Alloys

3- CHANGES IN MATTER
    3.1- Chemical changes or reactions
           .Oxidation
           .Combustion
   3.2- Chemical reactions of life
   3.3- Chemical reactions in industry  
   3.4- CHANGE IN STATE OF MATTERa change in temperature
           .melting melting point
           .solidification
           .vaporization-boilingboiling point
                              -evaporation
          .condensation
          .sublimation -reverse sublimation
   3.5- Examples of making use of changes of state