Chapter 15 Section 1

Matter  Materials are made of a ______________ substance or a ______________ of substances.  Pure  Mixture  What is a substance?  Type of matter with a fixed composition

Matter  What are the two types of substances we can have?  Element  Compound

Elements  What is an element?  All the atoms in a substance are the same  Look at the periodic table what are some common elements?  Oxygen, Hydrogen, Copper, Zinc

Elements  Are all elements found on Earth?  90 elements found on Earth  20 have been made in the lab  Do the elements made in the lab last a long time?  No, they are unstable and exist for only a short period of time

Compounds  Define Compound:  2 or more elements that have combined together to form a substance  The elements are present in a fixed proportion.  Water has 2 atoms of Hydrogen and 1 atom of Oxygen

Mixtures  What are the two types of mixtures?  Homogeneous  Heterogeneous  What is the difference between these two types of mixtures?

Mixtures  When you make soup does it always contain the same amount of each ingredient each time?  No because mixtures do not always contain the same proportions of substances that make them up.

Mixtures  Heterogeneous mixture:  Mixture in which different materials can easily be distinguished.  Examples:  Pizza toppings  Dry soup mixes  Clothing fabrics when looked at under a microscope

Mixtures  Homogeneous mixture:  Contains 2 or more gaseous, liquid, or solid substances blended evenly throughout  Examples: 1. Pop 2. Vinegar

Mixtures  Solution:  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

Colloid  What is a colloid?  A specific kind of mixture  Like a heterogeneous mixture it contains varying proportions of its components  Like a solution the components won’t settle out

Colloid  Colloid:  Type of mixture with particles that are larger than those in solutions but not heavy enough to settle out  Colloid is the Greek word for glue  Examples:  Paint  Fog

Detecting Colloids  How can you tell a colloid from a solution? 1. Appearance : If you can pass a light beam through it then it is a colloid  Light beams are invisible through a solution  This occurs because the particles in a colloid are large enough to scatter light.  Tyndall effect

Suspensions  Some mixtures are neither solutions or colloids  Ex: Pond Water  Suspension:  Heterogeneous mixture containing liquid in which visible particles settle  Ex: River Deltas

DescriptionSolutionColloidSuspension Settle upon standing? No Yes Separate using filter paper? No Yes Particle Size0.1-1 nm nmGreater than 1000 nm Scatter lightNoYes