Post on 04-Jan-2016
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Chap 1 Matter and ChangeHonors Chemistry
1.0:Chemistry
Chemistry – the study of the composition of substances and the changes they undergo
Five major divisions:
Organic – carbon compounds
Inorganic – substances without carbon
Analytical – composition of substances
Physical – theories and experiments describing behavior of chemicals
Biochemistry
1.1:Properties of MatterSubstance
Physical property
Chemical property
States of matter
Solid
Liquid
Gas
Vapor
Substances
Matter is anything that has mass and volume
Matter that is always the same is a pure substance
Water, H20, is a pure substance but well water is not because it may have different levels of salts and minerals in it
Physical Properties
A characteristic of a substance that can be observed without changing the substance is a physical property.
Density, color, melting point, and boiling points are all physical properties
Extensive and Intensive PropertiesProperties that are dependent on the amount of a substance present are extensive properties
Mass, length, and volume are all extensive
Properties that are not dependent on the amount of a substance present are intensive properties
Density, melting points and boiling points are all intensive
Chemical Properties
The ability of a substance to change from one type of substance into another is a chemical property
Iron reacting with oxygen in the air to form iron oxide, or rust, is a chemical property
Water freezing is a physical property since it is still water, just in a different form
States of Matter
Solids generally have atoms that are close together and are held in position by strong attraction
Solids have a definite shape and a definite volume
Solids are difficult to compress since their atoms are already so close together
States of Matter...
Liquids are made of atoms that are somewhat attracted to each other and are able to move around
Liquids have a definite volume but not a definite shape
Since liquids are free to move they cannot be compressed
States of Matter...Gases are not dense as they are made of quickly moving atoms that are widely spaced apart and have little to no attraction to each other
Since the atoms of a gas are so far apart, gases can be compressed
A vapor is used to describe substances in the gaseous form that are not gas at room temperature i.e. water vapor but carbon dioxide gas
1.2: Changes in Matter
Physical change
Chemical change
Law of conservation of mass
Physical and Chemical ChangesPhysical changes do not change the type of substance
Bending, melting, grinding and crushing are all examples of physical changes
Chemical changes do change the type of sustance
Milk spoiling, leaves rotting, iron rusting are all examples of chemical changes
Conservation Of MassThe first law of thermodynamics states that matter and energy cannot be created or destroyed.
As a result, every chemical change must obey the law of conservation of mass; the mass of the reactants must equal the mass of the products
Antoine Lavoisier, known as the father of chemistry, was the first to document this observation
Father of Chemistry??
1.3: Mixtures of Matter
Mixture
Heterogeneous mixture
Homogeneous mixture
Solution
Filtration
Distillation
Crystallization
Chromatography
MixturesA mixture is a combination of two or more substances that are not chemically combined
Mixtures can be heterogeneous (different throughout) or homogeneous (same throughout)
Homogeneous solutions are also called solutions
Solutions do NOT have to be liquid
An alloy is a homogeneous mixture of metals
An example is steel
Separating MixturesMixtures can be separated into their parts by a variety of methods.
Filtration separates liquid and solid mixtures using a porous barrier
Distillation separates liquid mixtures based on differences in boiling points
Crystallization involves solid particles forming out of solution
Chromatography separates pigments based on differences in solubilities
1.4: Elements and Compounds
Element
Periodic table
Compound
Law of definite proportions
Percent by mass
Law of multiple proportions
Elements
All matter is made of atoms
There are about 100 different types of atoms that we know of. These are the elements
Elements are pure substances that cannot be broken down by normal chemical means
Each element has its own one, two, or three letter symbol. The first letter in the symbol is always capitalized.
Periodic Table
The periodic table is a list of all the known elements
The specific placement and arrangement of the elements on the periodic table tells you a lot about the element
Rows on the periodic table are called periods and columns are called groups or families
Elements in the same group share chemical properties
Periodic Table....
CompoundsA combination of two or more elements in a specific ratio is a compound
Compounds are not mixtures because the elements are chemically combined
Chemical formulas are a combination of symbols and subscripts, numbers listed after and below the symbol, detailing the ratio between the elements in the compound
For example, H20, is made of two hydrogen atoms and one oxygen atom
Compounds...Compounds can be separated into their elements by chemical means. In other words, a reaction must take place to break a compound apart.
Compounds are often more stable than atoms alone. As a result, energy is often needed to separate a compound into its elements.
The chemical properties of compounds are different than the properties of the elements that make the compound
For example, NaCl is made from sodium, a metal that reacts explosively with water, and chlorine, a poisonous gas. Yet NaCl, table salt, is tasty on french fries!
Law of Definite Proportions
Regardless of the amount of the compound present, the ratio of the elements that compose the compound are always the same. This is the law of definite proportions
Each sample of a compound displays the same percent by mass of each element
Percent by mass = mass of the element__ x100% a mass of the compound
Law of Multiple Proportions
Some elements combine in different ways to make a variety of compounds. For example, hydrogen and oxygen combine to form water, H20, but also hydrogen peroxide, H202
The law of multiple proportions states that when different compounds are formed from the same elements, each compound has its own distinctive ratio of elements