Chapter 1 Lesson 1 Chem 105 Kristen Kull SIMS 115 Kristen Kull Kristen Kull CHEM105 General Chemistry I (Kull) CHEM105 General Chemistry I (Kull) Course Information Course Information Course Schedule Course Schedule WebCT

Chapter 1 Lesson 1 Chapter Classifying matter Chapter 1 Matter and Measurement 1.1 Classifying matter Matter consists of atoms and molecules in motion

Chapter 1 Lesson 1 STATES OF MATTER SOLIDS — have rigid shape, fixed volume. External shape can reflect the atomic and molecular arrangement. SOLIDS — have rigid shape, fixed volume. External shape can reflect the atomic and molecular arrangement. –Reasonably well understood. LIQUIDS — have no fixed shape and may not fill a container completely. LIQUIDS — have no fixed shape and may not fill a container completely. –Not well understood. GASES — expand to fill their container. GASES — expand to fill their container. –Good theoretical understanding.

Chapter 1 Lesson Elements and atoms Periodic table – names, symbols, masses of Periodic table – names, symbols, masses of CHEMICAL ELEMENTS - CHEMICAL ELEMENTS - –pure substances that cannot be decomposed by ordinary means to other substances. An atom is the smallest particle of an element that has the chemical properties of the element. An atom is the smallest particle of an element that has the chemical properties of the element. An atom consists of a nucleus An atom consists of a nucleus (of protons and neutrons) and electrons in space about the nucleus.

Chapter 1 Lesson Compounds and Molecules Compound – two or more different elements Compound – two or more different elements When elements are part of a compound, original properties are replaced by characteristic properties When elements are part of a compound, original properties are replaced by characteristic properties A MOLECULE is the smallest unit of a compound that retains the chemical characteristics of the compound. A MOLECULE is the smallest unit of a compound that retains the chemical characteristics of the compound.

Chapter 1 Lesson Physical properties Properties which can be measured without changing the composition of the substance Properties which can be measured without changing the composition of the substance Chemists are interested Chemists are interested in the nature of matter and how this is related to its atoms and molecules. Graphite: layer structure Graphite: layer structure of carbon atoms reflects physical properties.

Chapter 1 Lesson 1 Physical Properties - color -melting and boiling point -odor Physical Changes boiling of a liquid boiling of a liquid melting of a solid melting of a solid dissolving a solid in a dissolving a solid in a liquid to give a homogeneous mixture — a SOLUTION.

Chapter 1 Lesson 1 Intensive property – not dependent on quantity (density) Intensive property – not dependent on quantity (density) Extensive property – varies with quantity (mass) Extensive property – varies with quantity (mass)

Chapter 1 Lesson 1 DENSITY - an important and useful physical property Mercury 13.6 g/cm g/cm 3 Aluminum 2.7 g/cm 3 Platinum

Chapter 1 Lesson 1 Problem A piece of copper has a mass of g. It is 9.36 cm long, 7.23 cm wide, and 0.95 mm thick. Calculate density (g/cm 3 ).

Chapter 1 Lesson 1 Strategy 1. Get dimensions in common units. 2. Calculate volume in cubic centimeters. 3. Calculate the density.

Chapter 1 Lesson 1 SOLUTION 1. Get dimensions in common units. 2. Calculate volume in cubic centimeters. 3. Calculate the density. (9.36 cm)(7.23 cm)(0.095 cm) = 6.4 cm 3 Note only 2 significant figures in the answer!

Chapter 1 Lesson 1 PROBLEM: Mercury (Hg) has a density of 13.6 g/cm 3. What is the mass of 95 mL of Hg in grams? In pounds? Solve the problem using DIMENSIONAL ANALYSIS.

Chapter 1 Lesson 1 Strategy 1.Use density to calc. mass (g) from volume. 2.Convert mass (g) to mass (lb) Need to know conversion factor = 454 g / 1 lb PROBLEM: Mercury (Hg) has a density of 13.6 g/cm 3. What is the mass of 95 mL of Hg? First, note that 1 cm 3 = 1 mL

Chapter 1 Lesson 1 1.Convert volume to mass PROBLEM: Mercury (Hg) has a density of 13.6 g/cm 3. What is the mass of 95 mL of Hg? 2.Convert mass (g) to mass (lb) ( 95 cm 3 )(13.6 g/cm 3 ) = 1.3 x 10 3 g

Chapter 1 Lesson Physical and Chemical changes Physical change: identity is preserved; not always the state (melting point) Physical change: identity is preserved; not always the state (melting point) Chemical change: new substances are produced Chemical change: new substances are produced

Chapter 1 Lesson Units of Measurement Qualitative: no measurements or numbers involved ex. color (observations) Qualitative: no measurements or numbers involved ex. color (observations) Quantitative: numerical information ex. Time, mass, volume Quantitative: numerical information ex. Time, mass, volume –Metric (SI) base units Table 1.2, page 26 –Selected prefixes used in the metric system, Table 1.3, page 27

Chapter 1 Lesson 1 Temperature Scales 1 kelvin degree = 1 degree Celsius Notice that 1 kelvin degree = 1 degree Celsius Boiling point of water Freezing point of water Celsius 100 ˚C 0 ˚C 100˚C Kelvin 373 K 273 K 100 K Fahrenheit 32 ˚F 212 ˚F 180˚F T (˚C)(˚F) – 32]T (˚C) = 5/9 [T(˚F) – 32] T (K) = t (˚C) T (K) = t (˚C)

Chapter 1 Lesson Making measurements Precision: how well several values agree Precision: how well several values agree Standard deviation Standard deviation Accuracy: how close to the accepted value Accuracy: how close to the accepted value Percent error Percent error

Chapter 1 Lesson Mathematics of Chemistry Exponential or scientific notation Exponential or scientific notation –No more significant than least significant Dimensional Analysis Dimensional Analysis –Always write your units; one will always cancel out