Properties of Matter Notes 1

1. Materials are made of a pure substance or a mixture of substances. 2. Substance: a type of matter with a fixed composition a. can be an element b. can be a compound c. all are made of atoms Substances 15.1 Composition of Matter

element: a substance in which all of the atoms have the same identity Examples: 1. the graphite in your pencil point 2. the copper coating of most pennies 3. Name 10 others Elements 15.1 Composition of Matter

About 90 elements are found on Earth, and more than 20 have been made in laboratories!

Can you imagine yourself putting something made from a silvery metal and a greenish-yellow, poisonous gas on your food? Write down the name of the substance I am describing… Compounds 15.1 Composition of Matter

A: Table salt …even though it looks like white crystals and adds flavor to food, its components—sodium and chlorine—are neither white nor salty… compounds look different than elements in them Compound: a substance in which the atoms of 2 or more elements are combined in a fixed proportion (ex. chalk = Ca, C, and O) Compounds 15.1 Composition of Matter

mixture: a material made up of two or more substances that can be easily separated by physical means examples: pizza, soda Mixtures 15.1 Composition of Matter

1. Most of the substances you come in contact with every day are heterogeneous mixtures. Some components are easy to see, like the ingredients in pizza, but others are not. Heterogeneous Mixtures 15.1 Composition of Matter For example, the cheese in pizza is also a mixture, but you cannot see the individual components.

Soda contains water, sugar, flavoring, coloring, and carbon dioxide gas. Homogeneous Mixtures 15.1 Composition of Matter Soda in sealed bottles is an example of a homogeneous mixture. What is a homogeneous mixture?

Homogeneous Mixtures 15.1 Composition of Matter homogeneous mixture: a mixture that contains two or more gaseous, liquid, or solid substances blended evenly throughout

Another name for a homogeneous mixture like soda is a solution. Homogeneous Mixtures 15.1 Composition of Matter solution : a homogeneous mixture of particles so small that they cannot be seen with a microscope and will never settle to the bottom of their container… remain constantly and uniformly mixed

15.1 Composition of Matter

Example: milk, fog, smoke Colloids 15.1 Composition of Matter colloid: a type of mixture with particles that are larger than those in solutions but not heavy enough to settle out.

1. One way to distinguish a colloid from a solution is by its appearance. Detecting Colloids 15.1 Composition of Matter 2. Fog appears white because its particles are large enough to scatter light. Sometimes it is not so obvious that a liquid is a colloid. 3. You can tell for certain if a liquid is a colloid by passing a beam of light through it.

A light beam is invisible as it passes through a solution, but can be seen readily as it passes through a colloid. This occurs because the particles in the colloid are large enough to scatter light, but those in the solution are not. Detecting Colloids (continued) 15.1 Composition of Matter Tyndall Effect: The scattering of light by colloidal particles

Suspensions 15.1 Composition of Matter suspension: a heterogeneous mixture containing a liquid in which visible particles settle Example: pond water

Suspensions (continued) 15.1 Composition of Matter The table summarizes the properties of different types of mixtures.

15.1 Section Check Question 1 A. colloid B. mixture C. substance D. solution A _______ is a type of matter with a fixed composition.

15.1 Section Check Answer The answer is C. A substance can be either an element or a compound.

15.1 Section Check Question 2 A. 5 B. 10 C. 30 D. 90 How many elements are found on Earth?

15.1 Section Check Answer The answer is D. About 90 elements are found on Earth, and more than 20 have been made in laboratories.

15.1 Section Check Question 3 How are compounds different from mixtures?

15.1 Section Check Answer The atoms in compounds are combined in fixed proportions and cannot be separated by physical means. A mixture is made of two or more substances that can be easily separated by physical means.