chapter1

=The Basics: Chemistry and the Scientific Method = //Chemistry// : the study of matter and the changes it undergoes //Scientific Method// : a systematic approach to research 1. Define problem 2. Experiment, observe, record 3. Hypothesize > under the same conditions (picture from kbagdanov.wordpress.com  )
 * Information is either qualitative or quantitative.
 * //qualitative// : consisting of general observations about the system
 * //quantitative// : comprising numbers obtained by various measurements and observations
 * //hypothesis// : a tentative explanation for a set of observations
 * //law// : concise verbal or mathematical statement of a relationship between phenomena that is always the same
 * //theory// : a unifying principle that explains a body of facts and/ or those laws that are based on them

Classifications of Matter
 //matter// : anything that has mass and occupies space chemsite.lsrhs.net

-Substances and Mixtures

 * //substance// : form of matter that has a definite composition and distinct properties
 * //mixture// : a combination of two or more substances in which the substances retain their distinct identities
 * <span style="font-family: Tahoma,Geneva,sans-serif;">//homogenous mixture// : composition of the mixture is the same throughout
 * <span style="font-family: Tahoma,Geneva,sans-serif;">//heterogeneous mixture// : composition of the mixture is not uniform

<span style="color: rgb(255,0,109); font-family: Tahoma,Geneva,sans-serif;">-Elements and Compounds

 * <span style="font-family: Tahoma,Geneva,sans-serif;">//element// : substance that can not be separated into simpler substances by chemical means
 * <span style="font-family: Tahoma,Geneva,sans-serif;">//compound// : a substance composed of atoms of two or more elements chemically united in fixed proportions

<span style="color: rgb(255,0,109); font-family: Tahoma,Geneva,sans-serif;">-The Three States of Matter <span style="font-family: Tahoma, Geneva, sans-serif;">
www.scittscience.co.uk <span style="color: rgb(255,0,109); font-family: Tahoma,Geneva,sans-serif;">
 * [[image:http://www.cofc.edu/%7Emartine/111LectWeek1_files/image008.jpg align="left" caption="solidliquidgas"]] ||
 * <span style="font-family: Tahoma, Geneva, sans-serif;">All substances can exist in three states: solid, liquid, and gas. The three states differ in distance between the molecules. Solids have molecules that are held close together, and as it melts to a liquid the molecules spread out more, and then when it is a gas the molecules are spread very wide.
 * <span style="font-family: Tahoma, Geneva, sans-serif;">The composition of the substance doesn't change as the state of matter changes. For example, with heating, a certain substance will melt to form a liquid. This temperature at which it melts is called the __melting point__. Further heating will change the liquid into a gas. This temperature at which this takes place is called the __boiling point.__

[[image:http://www.grc.nasa.gov/WWW/K-12/airplane/Images/state.gif width="599" height="262" align="left"]]
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<span style="color: #ff006d; font-family: Tahoma, Geneva, sans-serif;">-Physical and Chemical Properties
<span style="font-family: Tahoma,Geneva,sans-serif;"> <span style="font-family: Tahoma, Geneva, sans-serif;">All substances have properties that we can use to identify them. The two basic types of properties associated with matter are called Physical and Chemical properties. <span style="font-family: Tahoma, Geneva, sans-serif;">The more properties identified for a substance, the better we know the nature of that substance. These properties help model the substance and understand how the substance will behave under various conditions.
 * <span style="font-family: Tahoma, Geneva, sans-serif;">Physical properties : properties that do not change the chemical nature of matter
 * <span style="font-family: Tahoma, Geneva, sans-serif;">Some examples are....color, smell, freezing point, melting point, attraction or repulsion to magnets, density and viscosity.
 * <span style="font-family: Tahoma, Geneva, sans-serif;">Chemical properties : properties that do change the chemical nature of matter.
 * <span style="font-family: Tahoma, Geneva, sans-serif;">Some examples are...heat of combustion, reactivity with water, PH, and electromotive force.
 * <span style="font-family: Tahoma, Geneva, sans-serif;">Extensive property : depends on how much matter is being considered
 * <span style="font-family: Tahoma, Geneva, sans-serif;">mass : quantity of matter in a given sample of a substance
 * <span style="font-family: Tahoma, Geneva, sans-serif;">volume : length cubed
 * <span style="font-family: Tahoma, Geneva, sans-serif;">Intensive property : does not depend on quantity of matter being considered
 * <span style="font-family: Tahoma, Geneva, sans-serif;">density : mass divided by volume
 * <span style="font-family: Tahoma, Geneva, sans-serif;">temperature

<span style="color: rgb(255,0,109); font-family: Tahoma,Geneva,sans-serif;">-SI Units
<span style="font-family: Tahoma, Geneva, sans-serif;">International System of Units ( abbreviated SI for the French Systeme Internationale d'Unites) __**SI BASE UNITS**__ Length --> meter Mass --> kilogram Time --> second Electrical current --> ampere Temperature --> kelvin Amount of substance --> mole Luminous Intensity --> candela ==
 * BASE QUANTITY ---> UNIT**

Example 1: 10-6 kg = 1mg (one milligram), **but not** 10-6 kg = 1 µkg (one microkilogram)
==Example 2: Consider an example of the height of the Washington Monument. You can write it in more than one form. //h//W = 169 000 mm = 16 900 cm = 169 m = 0.169 km 9 (using the millimeter, centimenter, or kilometer)==

<span style="color: rgb(255,0,109); font-family: Tahoma,Geneva,sans-serif;">-Mass and Weight
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 * <span style="font-family: Tahoma, Geneva, sans-serif;">The terms "mass" and "weight" are often used interchangeably even though they are totally different quantities, when strictly speaking.
 * <span style="font-family: Tahoma, Geneva, sans-serif;">mass : measure of the amount of matter in an object
 * <span style="font-family: Tahoma, Geneva, sans-serif;">weight : the force that gravity exerts on an object
 * <span style="font-family: Tahoma, Geneva, sans-serif;">weighing : the process of measuring mass

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<span style="color: rgb(0,255,0); font-family: Tahoma,Geneva,sans-serif;">***all this information was extracted from the Chang Chemistry textbook <span style="font-family: Tahoma,Geneva,sans-serif;">

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<span style="font-family: Tahoma,Geneva,sans-serif;"> Chapter 1 : continued