chapter 1 chemistry: the science of matter section 1.1: the puzzle of matter section 1.2: properties...
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Chapter 1 Chemistry: The Science of MatterSection 1.1: The Puzzle of Matter
Section 1.2: Properties and Changes of Matter
Section 1.1 Objectives
Classify matter according to its composition.
Distinguish among elements, compounds, homogeneous mixtures, and heterogeneous mixtures.
Relate the properties of matter to its structure.
Composition, Structure and Behavior Chemistry- the science that investigates
and explains the structure and properties of matter.
Matter- anything that takes up space and has mass
Mass- the measure of the amount of matter that an object contains
Matter
Matter is all around you. Phone Your neighbor The desk The metal of your chair The air you are breathing
What isn’t matter Heat Light Thoughts Ideas Radio waves Magnetic fields
Mass
On earth we equate mass with weight.A bowling ball has a larger mass than a tennis
ball. I have more mass than the text book.
Matter
The structure of matter refers to its composition-what is it made of and how is it organized
The properties of matter describe the characteristics and behavior of matter.Changes matter undergoes
Comparing Composition and Behavior (Figure 1.2 page 5) Salt and Water
Salt is Na and Cl Water is H and O You can wash you hair in water, but not in salt. And
you sprinkle water over popcorn. Aspirin and Sucrose
Both are composed of C, H, and O You wouldn’t use aspirin to sweeten cereal or use
sucrose for a headache
Properties
You can determine some of the properties of a particular chunk of matter by examination and manipulation.What is its color? Is it a solid, liquid or gas? Is it soft or hard?Does it dissolve in water?
Properties of Iron
Strong, but can be flattened and stretched Does not dissolve in water Turns to a liquid at high temperatures Is a gray, shiny solid Is attracted to a magnet Conduct electricity
Properties and Composition
You may be able to determine many properties of a piece of matter by examining it and doing some simple tests.
However, you can not determine what it is composed of just by looking at it.
Examining Matter: The Macroscopic View of Matter The macroscopic view of matter is one in
which you touch, smell, taste and see.
The Submicroscopic View of Matter
Gives you a glimpse into the world of atoms You cannot see this world even with the most powerful
microscopic. Matter is made up of atoms Atoms are so small that a period at the end of a
sentence is made up of 100,000,000,000,000,000,000 (100 quintillion) carbon atoms.
If you could count all 100 quintillion atoms at a rate of three per second it would take you a trillion years to finish counting.
Macro, micro, submicro Macroscopic – I can see with my “naked” eye
Microscopic – I need a microscope to see
Submicroscopic – I can’t see even with the most powerful microscope
Scanning Tunneling Microscope (STM) Although you cannot see atoms the STM
can produce images on a computer screen that show the location of individual atoms.
Platinum
Using Models in Chemistry
In chemistry you will use macroscopic and sub-microscopic models to understand certain concepts.
Scientific model- a thinking device, built on experimentation, that helps us to understand and explain macroscopic observations.
Models
A model for the atom was discussed in Greece about 2,500 years ago. However, this was not a scientific model.
The scientific model of the atom was not proposed until the 1800’s and it has with stood much experimentation with little changes.
Classifying Matter
Matter can be classified by its composition There are two main types of classifications
Qualitative- an observation made without measurement.
Quantitative- an observation made with measurement
Qualitative vs. Quantitative
QualitativeThere are students in this roomSucrose contains carbon, oxygen and
hydrogen Quantitative
There are 24 students in this roomSucrose contains 42.1 g of carbon, 51.4 g of
oxygen and 6.5 g of hydrogen.
Pure vs. Mixture
Matter can be classified by its purity. Is the matter pure or is it a mixture? Pure in chemistry means it contains only the
same substance. Substance- matter with the same fixed
composition and properties. Can be an element or a compound Any sample of pure matter is a substance
Substances
The bag of sugar you buy at the store is pure sucrose. It all has the same properties and a fixed composition. Therefore, it is a substance.
Mixed Matter
Mixed matter is referred to as a mixture. Mixture- combination of two or more substances
in which the basic identity of the substances are not changed.
Mixtures do not have a specific composition. Mixtures can be separated into its components
by physical means.
Separating Mixtures
One way is by physical changes. Physical change- a change in matter that does
not involve a change in the identity of individual substances. Boiling Freezing Melting Evaporation Dissolving Crystallization
Physical Properties
Separation by physical changes takes advantage of the physical properties of the mixture.
Physical properties- characteristics that a sample of matter exhibits without any changes in its identity Solubility Melting and boiling point Color Density Electrical conductivity Physical state (solid, liquid or gas)
Types of Mixture
There are two types of mixtures:Heterogeneous
Hetero means “different”
Homogeneous Homo means “the same”
Heterogeneous Mixture
Heterogeneous Mixture- a mixture that does not have a uniform composition.You can see the different composition.Examples:
Granite Chef Salad Lucky Charms Cereal Orange Juice with pulp
Homogeneous Mixture
Homogeneous Mixture- a mixture with a uniform composition. You cannot tell that it is composed of more than one
substance Another name is a solution Examples:
Salt water Tea Sugar water
Solutions
Homogeneous mixture Examples:
Salt waterGasolineAirSteel
Alloys
Alloys- solid solutions that contain different metals and sometimes nonmetallic substance
Table 1.1 page 23
Table 1.1 Some Common AlloysName of Alloy % Composition
Stainless Steel 73-79% iron (Fe)
14-18% chromium (Cr)
7-9% nickel (Ni)
Bronze 70-95% copper (Cu)
1-25% zinc (Zn)
1-18% tin (Sn)
Brass 50-80% copper (Cu)
20-50% zinc (Zn)
Sterling Silver 92.5% silver (Ag)
7.5% copper (Cu)
14-karat gold 58% gold (Au)
14-28% silver (Ag)
14-28% copper (Cu)
18-karat white gold 75% gold (Au)
12.5% silver (Ag)
12.5% copper (Cu)
Solder (electronic) 63% tin (Sn)
37% lead (Pb)
Solutions
When you are dissolving a substance into another substance there are two important terms:Solute – the substance being dissolvedSolvent – the dissolving agent
Salt WaterSolute = NaClSolvent = H2O
Aqueous Solution
Aqueous Solution- a solution in which the solvent is water.
Examples: Soda Tea Contact-lens cleaner Clear cleaning liquids
Most processes of life take place in aqueous solutions.
Substance: Pure Matter
You and everything around you is made up of chemicals.
Elements: The Building Blocks
If you classify an unknown piece of matter as pure; it means that it is made up of one substance
There are two types of substancesCompoundsElements
Elements
Elements- a substance that cannot be broken down into simpler substances.
Simplest form of matter Building blocks for other types of matter All substance in the universe are:
Elements Compounds formed from elements Or mixtures of elements and compound
Elements
118 elements Examples:
Gold Carbon Lead
Elements combine to form millions of compounds.
Chemical elements are often referred to as the building blocks of matter
Elements
118 elements 90 occur naturally
Less than half of these are abundant The remainder are synthesized
Organizing the Elements
Elements are organized in the Periodic Table
The periodic table tells you:NameSymbolAtomic mass
Symbols
The symbols of the elements are extremely important to know.
You will only have to know the most common ones.
The symbols are a one to two letter representation of the elements.
Not all the symbols are the first or second letter of the elements name
Symbols
Oxygen O
Hydrogen H
Bromine Br
Chlorine Cl
Table 1.2 Some Historic Chemical Symbols
Element Symbol Origin LanguageAntimony Sb Stibium Latin
Copper Cu Cuprum Latin
Gold Au Aurum Latin
Iron Fe Ferrum Latin
Lead Pb Plumbum Latin
Potassium K Kalium Latin
Silver Ag Argentum Latin
Sodium Na Natrium Latin
Tin Sn Stannum Latin
Tungsten W Wolfram german
Compounds Are More Than One Element Compound – a chemical combination of two or
more different elements joined together in a fixed proportion.
Every compound has its own fixed composition Therefore, every compound has unique
chemical and physical properties. The properties of a compound are different from
the properties of the elements that make them up.
Compounds
More than 10 million are known (still growing) New natural compounds are being isolated from
plants and colonies of bacteria. New compounds are also being synthesized in
labs. Examples
Sucrose Salt Water
Formulas of Compounds
Formula – a combination of the chemical symbols that show what elements make up a compound and the number of atoms of each element.
Sucrose: Aspartame:
Table 1.3 Some Common Compounds
Compound Name FormulaAcetaminophen C8H9NO2
Acetic Acid C2H4O2
Ammonia NH3
Aspartame C14H18N2O5
Propane C3H8
Salt NaCl
Sodium Hydroxide NaOH
Sucrose C12H22O11
Water H2O
Review
What is the difference between an element and a compound?
What is the difference between a homogeneous mixture and a heterogeneous mixture?
What is the difference between a mixture and a compound?