Classification of Matter

Classification of Matter

Matter is anything that occupies space and has mass. All matter, at least in principle, can exist in three states: solid, liquid and gas.

Substances and Mixtures: A substance is matter that has a definite or constant composition and distinct properties. Examples are water, silver, ethanol, table salt, carbon dioxide etc. Over 13 million substances are known and the list is growing rapidly. A mixture is a combination of two or more substances in which the substances retain their distinct identities. Some examples are air, soft drinks, milk, cement etc.

Elements and Compounds: A substance can be either an element or a compound. An element is a substance that cannot be separated into simpler substances by chemical means. Examples are hydrogen, helium, sodium, iron, silicon etc. About 113 elements have been positively identified. Eighty-three of them occur naturally on earth and others have been created by scientists. A compound is a substance composed of atoms of two or more elements chemically united in fixed proportions. Examples are water, sodium chloride, silica etc.











Solution:
Solution is a homogeneous mixture of at least two substances. The component which is being dissolved is called solute and the component in which the solute is dissolved is called solvent. For gases and liquids, the solvent is the predominant substance, while the solute is present in lesser amounts. The particle size in solution is less than 10-7 cm.

Example: sugar solution, saline water, spirit, vinegar, sulfuric acid, carbonated water, etc.

Colloids:
Colloids are regarded as systems in which there are two or more phases, with one (the dispersed phase) distributed in the other (the continuous phase). Colloid particles having size 10-7 cm to 10-4cm may be seen in a beam of light such as dust in air in a "shaft" of sunlight. Milk, fog, and jelly are examples of colloids.




Suspension:
In contrast a suspension is a heterogeneous mixture of larger particles. These particles are visible and will settle out on standing. Examples of suspensions are: fine sand or sediments in water or tomato juice.

The principal difference among the types of mixtures is the size of the particles (solutes) that are mixed with the solvent. The particles of suspensions are much larger than those of colloids or solutions.

TYPES OF SOLUTIONS

Concentrations Example
Solute less than 50% Solvent more than 50%
Liquid Liquid Alcohol –water
Acetic acid- water Beer
vinegar
Solid Liquid Salt –water
Sugar – water
calcium carbonate (CaCO3)– water Saline solution
Sugar solution
hard water
Gas Liquid CO2 – water
Oxygen – water
Carbonated water
Oxygenated water
Gas Gas Oxygen- nitrogen Air


Properties of Solutions, Colloids and Suspensions

Solutions Colloids Suspensions
Particle Size: smaller than 10-7 cm 10-7 - 10-4 cm larger than 10-4 cm
Appearance: Transparent, uniform cloudy, uniform at least two components visible, not uniform
Separation Method: distillation distillation filtration
Effect of Light Beam: invisible visible variable


Physical and Chemical Properties and their Changes:

The properties of a substance are those characteristics that are used to identify or describe it. When we say that water is "wet", or that silver is "shiny", we are describing materials in terms of their properties. Properties can be divided into the categories of physical properties and chemical properties.

Physical properties are readily observable like color, size, luster, or smell. Chemical properties are only observable during a chemical reaction. For example, you might not know if sulfur is combustible unless you tried to burn it.

Another way of separating kinds of properties is to think about whether or not the size of a sample would affect a particular property. No matter how much pure copper you have, it always has the same distinctive color. No matter how much water you have, it always freezes at 0oC under standard atm conditions. Methane gas is combustible, no matter the size of the sample. Properties, which do not depend on the size of the sample involved, like those described above, are called intensive properties. Some of the most common intensive properties are; density, freezing point, color, melting point, reactivity, luster, malleability, and conductivity.

Extensive properties are those that do depend on the size of the sample involved. A large sample of carbon would take up a bigger area than a small sample of carbon, so volume is an extensive property. Some of the most common types of extensive properties are; length, volume, mass and weight.

Pieces of matter undergo various changes all of the time. Some changes, like an increase in temperature, are relatively minor. Other changes, like the combustion of a piece of wood, are fairly drastic. These changes are divided into the categories of Physical and Chemical change. The main factor that distinguishes one category form the other is whether or not a particular change results in the production of a new substance.

Physical changes are those changes that do not result in the production of a new substance. If you melt a block of ice, you still have H2O at the end of the change. If you break a bottle, you still have glass. Painting a piece of wood will not make it stop being wood. Some common examples of physical changes are; melting, freezing, condensing, breaking, crushing, cutting, and bending. Special types of physical changes where any object changes state, such as when water freezes or evaporates, are sometimes called change of state operations.

Chemical changes, or chemical reactions, are changes that result in the production of another substance. When you burn a log in a fireplace, you are carrying out a chemical reaction that releases carbon dioxide. When you light your Bunsen burner in lab, you are carrying out a chemical reaction that produces water and carbon dioxide. Common examples of chemical changes that you may be somewhat familiar with are; digestion, respiration, photosynthesis, burning, and decomposition.








Some Questions:

1. Which of the following chemicals are elements and which are compounds?

a. water
b. ammonia
c. oxygen
d. sulfur
e. carbon dioxide
f. copper(II) sulfate
g. ferrous oxide

2. What are examples of simple mixtures?

3. How do mixtures separate?

4. Classification - State whether each of the following changes would be physical or chemical.
1) melting ice 2) burning wood 3) breaking glass 4) painting wood
5) cooking 6) burning propane 7) Mixing Salt & Water 8)healing of a wound

5. Define - Use your own words to define each of the following terms in the space provided.

Chemical Change -

Physical Change -

Change of State Operation -