The following slides are designed to help you in your study of matter. Matter is the basis for the second half of this course. 1) Basic definitions
Relationships between those definitions and the concepts
they help explain.
Pictures and diagrams to help visualize and understand
Sample problems to help prepare you for mastery
assignments and quizzes.
There are fill-in-the-blank notes associated with these powerpoints. You may complete those notes for one of your graded mastery assignments.
MATTER AND ENERGY Dark matter, matter we cannot see. Perhaps it doesn’t have or emit light. Scientists look at galaxy clusters and determine the amount of gravity holding the cluster together. From this information they can determine mass. They find there is a great deal more mass than they can account for from the visible material, thus the proposed existence of a “new” kind of matter, dark matter.
Composition - what matter is made of. Water is made of hydrogen and oxygen (H 2 O), tea has caffeine
Properties -what matter is like. For example, water can dissolve many substances and caffeine is a stimulant.
PROPERTIES OF MATTER What caffeine is made of… What caffeine is like…
THE BASIC UNIT OF MATTER IS AN ATOM There are over 118 varieties of atoms PERIODIC TABLE http:// www.webelements.com /scandium/
ELEMENTS contain only one type of atom. Ex: hydrogen (H) is an element that contains only hydrogen atoms, carbon (C) contains only carbon atoms, oxygen (O) contains only oxygen atoms, etc. Atoms of elements can combine together to form compounds. COMPOUNDS are neutral groups of atoms held together by chemical bonds. Ex: CO 2 , H 2 O, H 2 , O 2
Pure substance -a type of matter where all samples, no matter how big or small, have the same properties…they behave in exactly the same way.
Elements contain one type of atom, thus they CANNOT be broken down into simpler substances by chemical means.
Elements consist of either:
single atoms, such as Carbon (C), or Sodium (Na)
groups of atoms of the same type (molecules), such
as H 2 , O 2 , Br 2 , etc.
ELEMENTS MONATOMIC ELEMENTS DIATOMIC ELEMENTS ALLOTROPES Atomic nitrogen N Molecular nitrogen N 2 Ozone O3 Atomic hydrogen H Molecular hydrogen H 2 Graphite, buckyball Atomic oxygen O Molecular oxygen O 2 Carbon C ALLOTROPE-different forms of an element in same physical state
ELEMENTS TO COMPOUND COMBINED WITH… Will Form… Sodium, Na, is a soft, shiny metal that can be cut with a butter knife. When in contact with moisture it will “explode”. Chlorine gas, Cl 2 , which is a green, poisonous gas once used as a chemical weapon in military operations.
Sodium metal and chlorine gas, under the right conditions, undergo a chemical change and combine to become….. 2 Na (s) + Cl 2(g) 2 NaCl The final compound has properties different from the elements that formed it. TABLE SALT!
Mixtures are combinations of 2 or more substances where each substance retains its individual properties.
HOW ARE MIXTURES DIFFERENT FROM COMPOUNDS? HOW ARE MIXTURES LIKE COMPOUNDS? THEY ARE MADE FROM TWO OR MORE SUBSTANCES MIXTURES DO NOT FORM CHEMICAL BONDS.
Classifying mixtures There are two types of mixtures: 2) HETEROGENEOUS 1) HOMOGENEOUS
HOMOGENEOUS … a mixture that is the same throughout. A homogeneous mixture has a composition and properties that are identical regardless of the sample Ways to identify a homogeneous mixture: A SOLUTION is another name for a homogeneous mixture is
won’t settle out
HETEROGENEOUS … a mixture that is visibly different throughout. Heterogenous mixtures have a composition and properties that differ in any given sample. is Ways to identify a homogeneous mixture:
Colloids are evenly mixed, but their particles are too large to be considered homogeneous mixtures, which are also the same throughout.
Colloids show the Tyndall Effect. The Tyndall effect is the scattering of light as a beam passes through a colloid. In each picture, the colloid on the left scatters the beam making it visible
Mixtures Summary Ex. salt-water solution, tea, Cool-Aid drink Ex.: salt & pepper mix, rocks, cereal, bag of assorted candy Not as easily separated Can be easily separated Individual components can not be easily seen Individual components can be easily seen Properties of combined components are usually different than those of each component Individual components retain their own properties Evenly mixed Not evenly mixed Homogeneous Mixture Heterogeneous Mixture
Practice Problems 1. He 2. Ho 3. Ho 4. He 5. He 6. Ho 7. He 8. He 9. He 10. Ho 6. Tea 7. Banana nut bread 8. Pizza 9. Blood 10. Brass Determine whether each is a heterogeneous or homogeneous mixture: Answers: Return to index
Made of either elements or compounds that are chemically bonded.
Cannot be separated by physical means.
When combined they take on new properties different from the original elements.
Glucose: C 6 H 12 O 6
Table Salt: NaCl
Oxygen Gas: O 2
Carbon Dioxide CO 2
Two or more substances mixed together but not chemically combined.
Tea = Crushed Leaf + H 2 O
Rocks = minerals + sediments + organic matter
Sugar Water = Sugar + H 2 O
Each component retains its own identity; it does not change into something else.
Can be separated by physical means
Air (O 2 , N 2 , CO 2 , Ar)
Now, lets put it all together and determine how to tell substances (compounds and elements) from mixtures .
Elements, Compounds, and Mixtures Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3 rd Edition, 1990, page 68 Two of the descriptions to the right apply to each bottle below. Determine the appropriate descriptions .
Two types of atoms evenly mixed
Two types of atoms chemically combined
One type of atom
Two types of atoms mixed
2_______ 1_______ 3_______ 4_______ d & h b & g c & e a & f Return to Index hydrogen atoms oxygen atoms hydrogen atoms
Classifying Matter Matter Pure Substances Mixtures Elements Compounds Homogeneous Heterogeneous He, O H 2 O, NaCl Tea, kool-aid Rocky Road ice cream, muddy water Review: How matter is classified
Classify the following substances as: Pure substance, heterogeneous mixture, or homogeneous mixture Return to index More review Gatorade Homogenous mixture Fruit Loops Heterogeneous mixture Pure substance Gasoline Dirt Heterogeneous mixture Sugar Crystals Pure Substance Air Homogeneous mixture Granite Heterogeneous mixture