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A brief review of
Chemistry
A few general terms…
Anything that takes up space is termed matter.
An element is a substance that cannot be broken down into simpler substances.
Elements• Elements are represented by a large letter (or letters)
(such as C, N, Na or O) on a large chart called the periodic table.
Symbols you should memorize(Quiz tomorrow)
Carbon = Sulfur = Potassium = Nitrogen = Hydrogen = Phosphorus = Sodium = Iron = Oxygen = Clorine = Copper =
The smallest particle of an element which retains the characteristics of that element is an atom.
On the diagram of an atom bellow, label the:
Protons with an A Electrons with a B Neutrons with a C
How many protons are there? _____ How man electrons are there? ____ How many neutrons are there? ____
Using the periodic table, can you figure out what element this is?
Hint: Atomic number = the number of protons in the nucleus
When two or more elements come together to form a new product, the process is called a chemical reaction.
The resulting product, which is a new combination of elements is called a compound.
Every compound has a unique formula which shows how many atoms of each are in the compound. (eg. CO2)
The smallest unit of a compound that still retains the properties of the compound is called a molecule.
Mixtures and Solutions
Any two substances that are not chemically combined but are together is called a mixture.
A solution is a class of mixtures in which the molecules are evenly distributed.
The substance being dissolved is the solute.
The medium in which the substance is being dissolved is called the solvent.
Molecules that can be dissolved are termed soluble.
Molecules that cannot be dissolved are termed insoluble.
Acids and Bases
The pH scale measures the acidity or basicity of a substance.
An indicator is a chemical used to test for pH.
An acid or base usually produces a color change in the indicator.
Electricity is also used to measure pH.
http://www.fossweb.com/
Acids
An acid has a high concentration of dissolved H+ ions.
It has a pH less than 7
Some examples of acids are sulfuric acid (H2SO4); hydrochloric acid ( HCl) and acetic acid (CH3COOH)
Bases
A base has a high concentration of OH- ions.
It has a pH of more than 7.
Some examples of bases are ammonia (NH3) and acetate ion (C2H3O2
-).
Introduction to chemical Reactions
What does the word “chemical” mean to you?
Chemical: a single substance with distinctive properties
All matter is in the form of chemicals.
A chemical always reacts the same way under any given circumstance.
What is the difference between a chemical change and a physical change?
Chemical Change: a new chemical is formed
Examples: rusting, rotting, burning
Signs of a chemical change – color change, release of gas, new substance formed, energy released
Physical Change: NO new chemical is formed
Examples: breaking, dissolving, boiling, evaporating, melting, eroding, freezing, grinding, subliming
Indentify which of the following are chemical (C) or physical (P) changes:
1. a solid stretches when gently pulled ___2. a powder dissolves in water __3. a solid burns when ignited __4. a liquid changes color when exposed to air for a long time __5. a solid shatters into small pieces when hit with a hammer __6. a gas “pops” when a burning match is placed close by __7. solid becomes a gas when slightly warmed __8. a liquid evaporates in hot weather __9. limewater becomes cloudy when a gas passes through it __
A chemical change is also called a “chemical reaction.” How do we write a chemical reaction?
Where are the “reactants” in an equation?
Where are the “products” in an equation?
What is the term for all the chemical reactions that occur in an organism? Metabolism
Types of Reactions
Synthesis reactions: ANABOLISM
A + B ABatoms, ions, or molecules combine to form a new molecule
Example: combining of amino acids to form proteins
Types of Reactions
Decomposition Reactions: CATABOLISM
AB A + B Molecule breaks apart to form atoms, ions, or molecules
Example: chemical digestion of food particles into basic nutrients
