1. Matter can be classified by its state.
 Solids have a set volume and shape.The inter molecular force of attraction for solid matter is very
strong.
 Liquids have a set volume, but change shape. The inter molecular force of attraction for liquid matter
is weaker than solid matter.
 Gases have neither definite volume nor shape. The inter molecular force of attraction for gaseous
matter is negligible.
 Plasma which are usually gaseous state of matter in which a part or all of the atoms or molecules are
dissociated to form ions.
Matter can also be classified by its chemical composition.
 An element is a pure substance made up of atoms with the same number of protons. As of 2011, 118
elements have been observed, 92 of which occur naturally. Carbon (C), Oxygen (O), Hydrogen (H)
are examples of elements. Theperiodic table is a tabular representation of the known elements.
 A compound consists of two or more chemical elements that are chemically bonded together. Water
(H2O) and table sugar (C12H22O11) are examples of chemical compounds. The ratio of the elements in
a compound is always the same. For example in water, the number of H atoms is always twice the
number of O atoms.
 A mixture consists of two or more substances (element or compound) mixed together without any
chemical bond. Salad is a good example. A mixture can be separated into its individual components
by mechanical means.
Homogeneous Mixtures
 Soda water is a homogeneous mixture. (The straw looks broken because of refraction.)
 A homogeneous mixture is uniform, which means that any given sample of the mixture will have
the same composition. Air, sea water, and carbonation dissolved in soda are all examples of
homogeneous mixtures, or solutions. No matter what sample you take from the mixture, it will
always be composed of the same combination of phases. Chocolate chip ice cream is not
homogeneous—one spoonful taken might have two chips, and then another spoonful might have
several chips.
 An example for a homogeneous mixture is a solution. The substance that gets dissolved is
the solute. The substance that does the dissolving is the solvent. Together they make
a solution. If you stir a spoonful of salt into a glass of water, salt is the solute that gets dissolved.
Water is the solvent. The salty water is now a solution, or homogeneous mixture, of salt and
water.
 When different gases are mixed, they always form a solution. The gas molecules quickly spread
out into a uniform composition.

2. Heterogeneous Mixtures
 A heterogeneous mixture is not uniform. Different samples may have different compositions,
like the example of chocolate chip ice cream. Concrete, soil, blood, and salad are all examples of
heterogeneous mixtures.
Suspensions
 When sand gets kicked up in a pond, it clouds the water. Since it has a greater mass than water
hence it sinks to the bottom and settles down, and is no longer mixed into the water. This is an
example of a suspension. Suspensions are heterogeneous mixtures that will eventually settle.
They are usually, but not necessarily, composed of phases in different states of matter. Italian
salad dressing has three phases: the water, the oil, and the small pieces of seasoning. The
seasonings are solids that will sink to the bottom, and the oil and water are liquids that will
separate.
Colloids
 Toothpaste is a colloid, because it's part solid and part liquid.
 What exactly is toothpaste? We can't exactly classify it by its state of matter. It has a definite
shape and volume, like a solid. But then you squeeze the tube, and it flows almost like a liquid.
And then there's jelly, shaving cream, smoke, dough, and Silly Putty...
 These are examples of colloids. A colloid is a heterogeneous mixture of two substances of
different phases. Shaving cream and other foams are gas dispersed in liquid. Jello, toothpaste,
and other gels are liquid dispersed in solid. Dough is a solid dispersed in a liquid. Smoke is a
solid dispersed in a gas.
Colloids consist of two phases: a dispersed phase inside of a continuous medium.
The Tyndall Effect
 The Tyndall effect distinguishes colloids from solutions. In a solution, the particles are so fine that
they will not scatter light. This is not true for a colloid. If you shine light through a solution, the
beam of light will not be visible. It will be visible in a colloid. For instance, if you have ever played
with a laser pointer, you have seen the Tyndall effect. You cannot see the laser beam in air (a
solution), but if you shine it into a mist, the beam is visible. Clouds look white (or gray), as
opposed to blue, because of the Tyndall effect - the light is scattered by the small droplets of
suspended water.