Chapter 1 Chemistry: The Central Science What IS Chemistry Why “The Central Science” 1.2 The Scientific Method 1.3 Classification of Matter

Chapter 1 Chemistry: The Central Science What IS Chemistry Why “The Central Science” 1.2 The Scientific Method 1.3 Classification of Matter www.phwiki.com

Chapter 1 Chemistry: The Central Science What IS Chemistry Why “The Central Science” 1.2 The Scientific Method 1.3 Classification of Matter

Steade, Susan, Food Editor has reference to this Academic Journal, PHwiki organized this Journal Chapter 1 Chemistry: The Central Science CHEM 101 Dr. Geoff Sametz Fall 2009 What IS Chemistry Text: “The study of matter in addition to the changes that matter undergoes” Focus: how matter interacts at the atomic/molecular level Why “The Central Science” Other scientific disciplines require an underst in addition to ing of how matter behaves. Some examples: Physics: electronic devices require an underst in addition to ing of materials called semiconductors BiologyBiochemistryOrganic Chemistry (the study of carbon-containing compounds)

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Copyright McGraw-Hill 2009 1.2 The Scientific Method Copyright McGraw-Hill 2009 1.3 Classification of Matter Matter is either classified as a substance or a mixture of substances. Substance Can be either an element or a compound Has a definite (constant) composition in addition to distinct properties Examples: sodium chloride, water, oxygen

Copyright McGraw-Hill 2009 States of Matter Solid particles close together in orderly fashion little freedom of motion a solid sample does not con as long as m to the shape of its container Liquid particles close together but not held rigidly in position particles are free to move past one another a liquid sample con as long as ms to the shape of the part of the container it fills Copyright McGraw-Hill 2009 Gas particles r in addition to omly spread apart particles have complete freedom of movement a gas sample assumes both shape in addition to volume of container. States of matter can be inter-converted without changing chemical composition solid liquid gas (add heat) gas liquid solid (remove heat) Copyright McGraw-Hill 2009 States of Matter

Physical vs. Chemical Change In chemistry, we’re chiefly concerned with how atoms bond with each other. A chemical change involves making or breaking chemical bonds to create new substances. A physical change alters a substance without changing its chemical identity. -e.g. crushing, melting, boiling. Copyright McGraw-Hill 2009 Substances Element: cannot be separated into simpler substances by chemical means. Examples: iron, mercury, oxygen, in addition to hydrogen Compounds: two or more elements chemically combined in definite ratios Cannot be separated by physical means Examples: salt, water in addition to carbon dioxide Copyright McGraw-Hill 2009 Mixtures Mixture: physical combination of two or more substances Substances retain distinct identities No universal constant composition Can be separated by physical means Examples: sugar/iron; sugar/water

Copyright McGraw-Hill 2009 Molecular Comparison of Substances in addition to Mixtures Copyright McGraw-Hill 2009 Types of Mixtures Homogeneous: composition of the mixture is uni as long as m throughout Example: sugar dissolved in water Heterogeneous: composition is not uni as long as m throughout Example: sugar mixed with iron filings Copyright McGraw-Hill 2009 Classification of Matter

Copyright McGraw-Hill 2009 Classify the following Aluminum foil Baking soda Milk Air Copper wire Copyright McGraw-Hill 2009 Aluminum foil: substance, element Baking soda: substance, compound Milk: mixture, homogeneous Air: mixture, homogeneous Copper wire: substance, element Copyright McGraw-Hill 2009 1.3 Scientific Measurement Used to measure quantitative properties of matter SI base units

Copyright McGraw-Hill 2009 SI Prefixes Copyright McGraw-Hill 2009 Mass: measure of the amount of matter (weight refers to gravitational pull) Temperature: Celsius Represented by C Based on freezing point of water as 0C in addition to boiling point of water as 100C Kelvin Represented by K (no degree sign) The absolute scale Units of Celsius in addition to Kelvin are equal in magnitude Fahrenheit (the English system) (F) Copyright McGraw-Hill 2009 Equations as long as Temperature Conversions

Copyright McGraw-Hill 2009 Temperature Conversions A clock on a local bank reported a temperature reading of 28oC. What is this temperature on the Kelvin scale Copyright McGraw-Hill 2009 Practice Convert the temperature reading on the local bank (28C) into the corresponding Fahrenheit temperature. Copyright McGraw-Hill 2009 Volume: meter cubed (m3) Derived unit The unit liter (L) is more commonly used in the laboratory setting. It is equal to a decimeter cubed (dm3).

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Copyright McGraw-Hill 2009 Density: Ratio of mass to volume Formula: d = density (g/mL) m = mass (g) V = volume (mL or cm3) (gas densities are usually expressed in g/L) Copyright McGraw-Hill 2009 Practice The density of a piece of copper wire is 8.96 g/cm3. Calculate the volume in cm3 of a piece of copper with a mass of 4.28 g. Copyright McGraw-Hill 2009 1.4 Properties of Matter Quantitative: expressed using numbers Qualitative: expressed using properties Physical properties: can be observed in addition to measured without changing the substance Examples: color, melting point, states of matter Physical changes: the identity of the substance stays the same Examples: changes of state (melting, freezing)

Copyright McGraw-Hill 2009 Chemical properties: must be determined by the chemical changes that are observed Examples: flammability, acidity, corrosiveness, reactivity Chemical changes: after a chemical change, the original substance no longer exists Examples: combustion, digestion Copyright McGraw-Hill 2009 Extensive property: depends on amount of matter Examples: mass, length Intensive property: does not depend on amount Examples: density, temperature, color Copyright McGraw-Hill 2009 1.5 Uncertainty in Measurement Exact: numbers with defined values Examples: counting numbers, conversion factors based on definitions Inexact: numbers obtained by any method other than counting Examples: measured values in the laboratory

Copyright McGraw-Hill 2009 Notes on Problem Solving Read carefully; find in as long as mation given in addition to what is asked as long as Find appropriate equations, constants, conversion factors Check as long as sign, units in addition to significant figures Check as long as reasonable answer Copyright McGraw-Hill 2009 Practice The Food in addition to Drug Administration (FDA) recommends that dietary sodium intake be no more than 2400 mg per day. What is this mass in pounds (lb), if 1 lb = 453.6 g Copyright McGraw-Hill 2009 Key Points Scientific method Classifying matter SI conversions Density Temperature conversions Physical vs chemical properties in addition to changes Precision vs accuracy Dimensional analysis

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