Chemistry, The Central Science, 10th edition Theodore L. Brown; H. Eugene LeMay, Jr.; and Bruce E. Bursten Chapter 1Introduction:Matter and Measurement John D. Bookstaver St. Charles Community College St. Peters, MO 2006, Prentice Hall
Matter: Anything that has mass and takes up space.
Properties of Matter Physical Properties: Can be observed without changing a substance into another substance. Boiling point, density, mass, volume, etc. Chemical Properties: Can only be observed when a substance is changed into another substance. Flammability, corrosiveness, reactivity with acid, etc.
Properties of Matter Intensive Properties: Independent of the amount of the substance that is present. Density, boiling point, color, etc. Extensive Properties: Dependent upon the amount of the substance present. Mass, volume, energy, etc.
Changes of Matter Physical Changes: Changes in matter that do not change the composition of a substance. Changes of state, temperature, volume, etc. Chemical Changes: Changes that result in new substances. Combustion, oxidation, decomposition, etc.
Chemical Reactions In the course of a chemical reaction, the reacting substances are converted to new substances.
SI Units • There are two types of units: • fundamental (or base) units; • derived units. • There are 7 base units in the SI system.
SI Units Système International d’Unités Uses a different base unit for each quantity
Metric System Prefixes convert the base units into units that are appropriate for the item being measured.
Volume • The units for volume are given by (units of length)3. • SI unit for volume is 1 m3. • We usually use 1 mL = 1 cm3. • Other volume units: • 1 L = 1 dm3 = 1000 cm3 = 1000 mL.
Uncertainty in Measurements Different measuring devices have different uses and different degrees of accuracy.
Density: Physical property of a substance m V d=
Do now: A graduated cylinder is filled with 15.0 mL of water. An object with a mass of 29.66 g causes the total volume to increase to 23.4 mL. What is the density of the sample?
Vocabulary review • Mass : amount of matter in an object. • It is measured with a balance. • Unit in the SI system: grams g • Weight: a measure of the pull that the gravity exerts over an object. • If we stay in the same planet (same gravity) is used like the mass.
Volume • The space that an object occupies. • Unit of volume in SI Liter = L
What is density? • Density is a comparison of how much matter there is in a certain amount of space. • IT IS AN INTENSIVE PHYSICAL PROPERTY. It is used to identify a substance.
DENSITY OF WATER • 1g/ml • That means that a gram of water has a volume of 1 milliliter or 1 cubic centimeter.
Which one is more dense? • Now which one is more dense?
What is density? • Density = mass volume or • mass ÷ volume. Units for density: g . cm3 • Why are these the units for density? ALWAYS REMEMBER UNITS!
Let’s try a density problem together • Find the density of a yellow rock has a mass of 8 g and a volume of 4 cm3. • Use your table S to determine what element it could be!
IMMISCIBLE LIQUIDS • If you pour together liquids that don’t mix and have different densities, they will form liquid layers. • Liquids that don’t mix are said to be IMMISCIBLE • The liquid with the highest density will be on the bottom. • The liquid with the lowest density will be on the top.
Liquid Layers • . Which layer has the highest density? • Which layer has the lowest density? • Imagine that the liquids have the following densities: • 10g/cm3. 3g/cm3. • 6g/cm3. 5g/cm3. • Which number would go with which layer? • Is any of the liquids water?
To measure the volume of an object • If is a regular object measure the dimensions needed and use the formula • cube= LxWxH • Cylinder = p h r2 • For an irregular object use the water displacement method.
Liquid Layers – Try with your neighbor • Which liquid has the highest density? • Which liquid has the lowest density? • Which liquid has the middle density?
Liquid Layers – Try on your own! • Imagine that the liquids on the right have the following densities: • 15g/cm3 10g/cm3 • 3g/cm3 9g/cm3 • 7g/cm3 12g/cm3 • Match the colors to the correct densities. 3g/cm3 7g/cm3 9g/cm3 10g/cm3 12g/cm3 15g/cm3
Review • What is the formula for density? • What happens if you pour together liquids that have different densities? • Will the liquid on the top have the highest or lowest density? • Will the liquid on the bottom have the highest or lowest density?
Density worksheet answers • 1=1 • 2=2 • 3=2 D of Na 0.971 g/mL • 4=4 D of Mg 1.738 g/cm3 • 5=2 • 6 20g/24.4L = 0.82 g/L
HOMOGENEOUS : SAME PROPERTIES THROUGHOUT THE SAMPLE • HETEROGENEOUS : • DIFFERENT PROPERTIES IN DIFFERENT PARTS OF THE SAMPLE
PURE SUBSTANCEShave a constant composition • ELEMENTS – Made up of same kind of atoms. Could not be decomposed. • COMPOUNDS – Made up of different kind of atoms CHEMICALLY COMBINED. Can be decomposed. • Recognizable by formulas!
Compounds Compounds can be broken down into more elemental particles.
Matter • Atoms are the building blocks of matter.
Matter • Atoms are the building blocks of matter. • Each element is made of the same kind of atom.
Matter • Atoms are the building blocks of matter. • Each element is made of the same kind of atom. • A compound is made of two or more different kinds of elements.
SEPTEMBER 21 • ELEMENT , COMPOUNDS AND MIXTURES • REVIEW FOR TEST • PHYSICAL AND CHEMICAL PROPERTIES • PHYSICAL AND CHEMICAL CHANGES • DENSITY
MIXTURES • Combination of two or more pure substances. Can be separated by physical means. They do not have a fixed composition. • Can be homogeneous or heterogeneous. • SOLUTIONS ARE HOMOGENEOUS MIXTURES.
AQUEOUS SOLUTIONS The solution is prepared using water as the solvent (aq) means DISSOLVED IN WATER!!! Na Cl (s) is a compound Na Cl (aq) is a mixture!!!!
Pure Substances and Mixtures • If matter is not uniform throughout, then it is a heterogeneous mixture. • If matter is uniform throughout, it is homogeneous. • If homogeneous matter can be separated by physical means, then the matter is a mixture. • If homogeneous matter cannot be separated by physical means, then the matter is a pure substance. • If a pure substance can be decomposed into something else, then the substance is a compound.
Elements • If a pure substance cannot be decomposed into something else, then the substance is an element. • There are 114 elements known. • Each element is given a unique chemical symbol (one or two letters). • Elements are building blocks of matter. • The earth’s crust consists of 5 main elements. (O, Si, Al, Fe, Ca) • The human body consists mostly of 3 main elements. (O, C, H)
Symbols • First letter of element in CAPITAL letter • Second or third letter in lower case. • Some elements have symbols different from the english name • SODIUM Na • POTASSIUM K • CUPPER Cu • LEAD Pb
IRON Fe • MERCURY Hg • GOLD Au • SILVER Ag • TIN Sn
Symbols from Latin Names Element Symbol Latin name Copper Cu cuprum Gold Au aurum Lead Pb plumbum Mercury Hg hydrargyrum Potassium K kalium Silver Ag argentum Sodium Na natrium Tin Sn stannum
DIATOMIC ELEMENTS • H2O2F2Br2I2N2Cl2