mrsmurraysworld.weebly.commrsmurraysworld.weebly.com/.../7/4/8/27481187/chapter… · Web...
Transcript of mrsmurraysworld.weebly.commrsmurraysworld.weebly.com/.../7/4/8/27481187/chapter… · Web...
Chapter 1The Science of Chemistry
Section 1: What is Chemistry?
Section 2: Describing Matter
Section 3: How is Matter Classified?
Section 1.1 – What is Chemistry?
OBJECTIVES:Describe ways in which chemistry is part of your daily life.
Describe the characteristics of three common states of matter.
Describe the reactants and products in a chemical reaction.
Identify the reactants and products in a chemical reaction.
Differentiate between Chemical and Physical changes.
List four observations that suggest a chemical change has occurred.
Working with the Properties and Changes of Matter
• A chemical is any substance that has a definite composition.
• A chemical reaction is the process by which one or more substances change to produce one or more new substances.
Rank Name Formula Uses1 sulfuric acid H2SO4 Production of fertilizer, metal processing,
petroleum refining2 Ethane C2H4 Production of plastics, ripening of fruits3 Propylene C3H6 Production of plastics4 Ammonia NH3 Production of fertilizer, refrigeration5 Chlorine Cl2 Bleaching fabrics, purifying water, disinfectant6 Phosphoric acid
(anhydrous)P2O5 Production of fertilizer, flavoring agent;
rustproofing metals7 Sodium hydroxide NaOH Petroleum refining, production of plastics8 1,2-dichloroethene C2H2Cl2 Solvent, particularly for rubber
Top Eight Chemicals Made in the United States (by Weight)
Physical States of Matter
The states of matter are the physical forms of matter which are solid, liquid, gas, and plasma.
Macroscopic refers to what you can see with the unaided eye.
Microscopic refers to what you would see if you could see individual atoms.
Properties of the Physical States
Solids have a fixed volume and shape that result from the way their particles are arranged.
Liquids have a fixed volume but not a fixed shape.
Gases have neither fixed volume nor shape.
State Volume Shape Bond Particle Motion
Solid Fixed Fixed Strong Slight vibration
Liquid Fixed Takes the shape of the container Moderate Move past one another
Gas Varies Takes the shape of the container Weak Move apart at high
speeds
Changes of Matter
Physical changes are changes in which the identity of a substance doesn’t change.
Changes of state are physical changes.
Chemical changes occur when the identities of substances change and new substances form.
Chemical Changes
mercury(II) oxide mercury + oxygen
Reactants are the substances are the left-hand side of the arrow.
They are used up in the reaction.
Products are the substances are the right-hand side of the arrow.
They are made in the reaction.
Evidence of a Chemical ChangeEvidence that a chemical change may be happening generally
falls into one of the following categories.
the evolution of a gas the formation of a precipitate the release or absorption of energy a color change in the reaction system
Section 1.2 – Describing Matter
OBJECTIVES:Distinguish between different characteristics of matter, including
mass, volume, and weight.Identify and use SI units in measurements and calculations.
Set up conversion factors, and use them in calculations.
Identify and describe physical properties, including density.
Identify chemical properties.
Matter Has Mass and Volume
Matter is anything that has mass and volume.
Volume is the space an object occupies.
Mass is the quantity of matter in an object.
Devices used for measuring mass in a laboratory are called balances.Weight is the force produced by gravity acting on a mass.
Units of Measurement
• When working with numbers, be careful to distinguish between a quantity and its unit.
• Quantity describes something that has magnitude, size, or amount.
• Unit is a quantity adopted as a standard of measurement
Scientist Express Measurements in SI Units
Base units can be too large or too small for some measurements, so the base units may be modified by attaching prefixes.
SI Prefixes
Converting One Unit to Another
A conversion factor is a simple ratio that relates two units that express a measurement of the same quantity
example: You can construct conversion factors between kilograms and grams as follows:
Sample Problem A
Convert 0.851 L to milliliters.
The equality that links the two units is 1000 mL = 1 L. (The prefix milli- represents 1/1000 of a base unit.)
The conversion factor needed must cancel liters and leave milliliters. Thus, liters must be on the bottom of the fraction and milliliters must be on the top.
Derived Units
Many quantities you can measure need units other than the seven basic SI units.
These units are derived by multiplying or dividing the base units.
Speed is distance divided by time.The derived unit of speed is meters per second (m/s).
A rectangle’s area is found by multiplying its length (in meters) by its width (also in meters).
Its unit is square meters (m2).
Volume is another commonly used derived unit.
The volume of a book can be found by multiplying its length, width, and height.
The unit of volume is the cubic meter (m3).
This unit is too large and inconvenient in most labs. Chemists usually use the liter (L).
1L = 1000 mL = 1000 cm3
Worksheet – 1.2A
Convert the following (SHOW ALL WORK)
1. 253 mL L
2. 1256 cm m
3. 15 g kg
4. 1254 kilocalories calories
5. 5.25 hr seconds
6. 200° C °F
7. 189° F C°
Properties of MatterPhysical Properties
• A physical property of a substance is a characteristic that does not involve a chemical change.
• Physical properties of a substance can be determined without changing the nature of a substance.
• Physical properties include texture, state, melting point, and boiling point.
Density is the Ratio of Mass to Volume
• The density of an object is the mass of the object divided by volume of the object.
• Densities are expressed in derived units such as g/cm3 or g/mL.
• Density is calculated as follows:
The density of a substance is the same no matter what the size of the sample is.
Density Can Be Used to Identify Substances:
Because the density of a substance is the same for all samples, you can use this property to help identify substances
Densities of Various SubstancesHydrogen H2 .0000824
Water H2O .997Aluminum Al 2.699
Iron Fe 7.86Copper Cu 8.94Silver Ag 10.5Gold Au 19.3
Chemical Properties
A chemical property is a property of matter that describes a substance’s ability to participate in chemical reactions.
A chemical property can only be identified by trying to cause a chemical change.
A chemical property of many substances is that they react with oxygen.
example: rusting
Some substances break down into new substances when heated.
Section 1.3 – How Is Matter Classified?
OBJECTIVES:Distinguish between elements and compounds.
Distinguish between pure substances and mixtures.
Classify mixtures as homogeneous or heterogeneous.
Explain the difference between mixtures and compounds.
Atom: The smallest unit of an element that maintains the properties of that element.
Pure Substance:
A sample of matter, either a single element or a single compound, that has definite chemical and physical properties.
There are two(2) types of pure substances: elements, compounds
Element: A substance that cannot be separated or broken down into simpler substances by chemical means.
All atoms of an element have the same atomic number.
Elements are pure substances that contain only one kind of atom.
Ex. Copper and Bromine are elementsEach has its own unique set of physical and chemical properties and is represented by a distinct chemical symbol
Some elements exist as single atoms while some exist as molecules.Monatomic: Elements that exist as single atoms
Molecules: 2 or more atoms combined in a definite ratio.If an element consists of molecules, those molecules contain just one type of atom.
Element name Chemical symbol
Origin of symbol
Hydrogen H First letter of element name
Helium He First two letters of element name
Magnesium Mg First and third letters of element name
Tin Sn From stannum, latin word meaning “tin”
Gold Au From aurum, the latin word meaning “gold”
Tungston W From Wolfrum, the german word for “tungsten”
Ex. Nitrogen is an example of a molecular element because it exists as two(2) nitrogen atoms joined together.
Diatomic: Elements that exist as double atomsNitrogen is a diatomic element. Other diatomic elements are:Nirtogen (N2)Oxygen (O2)Hydrogen (H2)Flourine (F2)Chlorine (Cl2)Bromine (Br2)Iodine (I2)
Some elements exist in more than one formEx. Oxygen gas O2
A molecule where 2 oxygen atoms bond together
Ozone gas O3
A molecule where 3 oxygen atoms bond together
Compound: A substance made up of atoms of two or more different elements joined by chemical bonds.Compounds can be broken down into its individual elements although it can sometimes be a difficult task.
• Compounds can be represented by an abbreviation or formula. • A formula has subscripts which represent the ratio of different atoms in the
compound.• example: H2O has 2 hydrogen atoms and one
oxygen atom • Chemical formulas give information only about what makes up a compound.
• example: the chemical formula for aspirin is
C9H8O4
A structural formula shows how the atoms are connected
This two-dimensional model does not show the molecule’s true shape.
A ball-and-stick model shows the distances between atoms and the angles between them in three dimensions.
A space-filling model attempts to represent the actual sizes of the atoms and not just their relative positions.
A hand-held model can provide more information than models shown on the flat surface of the page.
Mixtures: A combination of two or more substances that are not chemically combined.Ex. Air is a mixture
Air consists mostly of oxygen and hydrogen whose proportions can varyWater is NOT a mixture
Water consists of oxygen and hydrogen whose proportions are exactly the same in every sample of water.In addition, the hydrogen and the oxygen are chemically combined not physically.
• The proportion of the materials in a mixture can change. • The properties of the mixture may vary.• An alloy is a solid mixture.
• example: An alloy of gold and other metal atoms is stronger than pure gold.• 18-karat gold contains 18 grams of gold per
24 grams of alloy.• 14-karat gold contains 14 grams of gold per
24 grams of alloy.
Homogeneous Mixture: The pure substances are distributed uniformly throughout the mixture.
Heterogeneous Mixture: The substances are not evenly mixed.
• Any two samples of a heterogeneous mixture will have the different proportions of ingredients.
• Heterogeneous mixtures have different properties throughout.
Examples of MixturesHomogeneous Iced Tea Uniform distribution of components; components cannot
be filtered out and components will not settle out upon
standing.Stainless steel Uniform distribution of components
Maple Syrup Uniform distribution of components; components cannot be filtered out and will not settle out upon standing.
Heterogeneous
Orange Juice Uneven distribution of components; settles out upon standing
Chocolate chip pecan cookie Uneven distribution of components
Granite Uneven distribution of components
Salad Uneven distribution of components and can be easily separated by physical means
Compound vs. Mixture
Compound MixtureChemically joined Physically mixed
Properties may be very different form elements
that makes it up
Properties of mixture reflects properties of substances it contains
Definite proportionComponents can be present in varying
proportions
Classifying Matter
Chapter 1 Assignments
Section 1.1 Pg 9 # 3- 12QUIZ – 1.1
Section 1.2 Worksheet 1.2ASection 1.2 Pg 19 # 1-13
QUIZ – 1.1 -1.2Section 1.3 Pg 28 # 1-8
Chapter Review Pg 31-33 # 1-31TEST – Chapter 1