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Chapter 9 Classification of Matter


9.1 Composition of Matter


Chemists study and classify matter Ė the endless array of materials that we come into contact with each day. Matter can be defined as anything that has mass and takes up space. It can be classified into three groups: elements, compounds and mixtures.




v    The units that make up all matter are called atoms.

v    If all the atoms in a sample of matter have the same identity that kind of matter is called an element. Oxygen, hydrogen, copper, zinc and lead are all elements.

v    An element is a substance that cannot be broken down into other substances.

v    Altogether there are 111 recognized elements.




v    Materials called compounds are made from atoms of two or more elements that are chemically combined. The ratio of the different atoms in a compound is always the same.

v    Hydrogen and oxygen can combine to form the compound water (H20): 2 atoms of Hydrogen and 1 atom of oxygen.

v    A compound that you eat almost daily consisting of a black element and two invisible gases is called sugar. It consists of carbon, oxygen and hydrogen.

v    Compounds usually have a different appearance from the elements that make them up. Water is made up of two elements that are flamable gases


v    A substance is either an element or a compound. Elements and compounds cannot be reduced to more basic components by physical processes. (heating, cooling, cutting, stretching etc.)


v    Oxygen, carbon, water, sugar, baking soda and salt are all examples of materials classified as a substance.




v    A mixture is a material made up of two or more substances that can be separated by physical means. Mixtures retain their individual properties. Saltwater is a mixture of water (H20) and salt (NaCl). Both water and salt are compounds.


v    A mixture in which different materials can be easily distinguished is called a heterogeneous mixture. Pizza, concrete (sand, gravel), dry soup mixes are examples. Heterogeneous mixtures can be seen with the naked eye or with a microscope.


v    Mixtures that are uniform throughout are homogeneous.




v    Mixtures that are clear (you canít see any particles) and are uniformly spread out are called a homogeneous mixture. Saltwater is a homogeneous mixture, so is a carbonated beverage (CO2 in H2O). Solutions are always clear. They can be colorless or colored.


v    A solution is another name for a homogeneous mixture. In a solution particles are so small they cannot be seen. They will never settle out.


Colloids and Suspensions


v    A colloid is a heterogeneous mixture that, like a solution, will never settle out.


v    Colloids scatter light. This effect is called the Tyndall effect.


v    A suspension is a heterogeneous mixture containing a liquid in which visible parts will settle out. Muddy water is an example.


v    A solute is any substance that dissolves into another substance. Salt is the solute in saltwater.


v    A solvent is the substance that some other substance dissolves into. Water is a solvent. It is the most common solvent in the universe.



Kinds of Solutions



Solid in Solid



Steel (Carbon and Iron)


Liquid in Solid



Rubber cement (benzene in rubber)



Gas in Solid



Alloy of Palladium and hydrogen


Solid in Liquid



Saltwater (salt in water)


Liquid in Liquid



Vinegar (acetic acid in water)


Gas in Liquid



Carbonated Beverage (carbon dioxide CO2 in water)



Gas in Gas





Solid in Gas



Perfume (perfume particles in air)


Liquid in Gas



Humid Air (water in air)