FiresticksA chemical reaction is an extraordinary transformation.Microscopic versus Macroscopic WorldsInterpretation of a situation depends on the manner in which it is framed.And so, why should nonscience majors study science (chemistry in particular)?

Molecular ReasonsChemistry is a world that is not readily apparent to the naked eye, yet it is the cause of all that is around us.

Chemists examine the molecular reasons for our macroscopic observations.

The Scientist and the ArtistIn a chemical reaction, matter is neither created nor destroyed.Antoine LavoisierFather of modern chemistryUnfortunate endLaw of conservation of massCapable of summary and prediction

The Scientific MethodA process by which a set of observations leads to a model of reality.Iterative process

The Scientific Method: StructureHypothesisExperimentTheoryFurther experimentationJohn Daltons formulation of atomic theory is an application of the scientific method.

Concept Check 1.1A newly discovered aqueous extract of a berry grown in southeast Asia is claimed to cure malaria. How would you classify this claim? Is this an example of a (a) fact, (b) theory, (c) hypothesis, or (d) myth?

Concept Check 1.1 SolutionConcept Check:A newly discovered aqueous extract of a berry grown in southeast Asia is claimed to cure malaria. How would you classify this claim? Is this an example of a (a) fact, (b) theory, (c) hypothesis, or (d) myth?

Solution:The claim that the extract cured malaria is classified as a (c) hypothesis. No evidence had been provided to prove or disprove the claim.

First WonderersGreek philosophersPlatoDemocritusThalesEmpedoclesAristotelian logicReigned for 2000 years

AlchemyGoal: transmutation of base metals into gold and discovery of the elixir of lifeMetallurgyMysticism and secrecy slowed any real scientific progress.

An UnderstandingThe scientific revolutionPublications by Copernicus and Vesalius emphasized observation and experimentation.Galileo Galileis ideas contradicted the teachings of Aristotle and the Catholic Church.Robert Boyles Skeptical Chymist criticized Greek ideas centered on four elements while further developing the concept of elements.

Classification of Matter Boyles Approach

Classification by Composition:Pure substanceElements cannot be decomposed to simpler forms by any amount of chemical transformation.Compounds are composed of two or more elements in definite proportions.

Classification by Composition:Mixtures are combinations of two or more pure substances in variable proportions. They are classified as homogeneous and heterogeneous.Homogeneous: A mixture that has the same composition throughout. Heterogeneous: A mixture that is separated into two or more regions with different composition.

Concept Check 1.2Determine whether each of the following is an element, a compound, or a mixture. If it is a mixture, classify it as homogeneous or heterogeneous.14 carat gold ringsandcarbon dioxidediamond

Concept Check 1.2 Solution14 carat gold24 carat gold is pure gold. 14 carat gold is a homogeneous (solid-solid) mixture of gold and other elements such as copper or nickel.sandSand is heterogeneous mixture of quartz and other minerals. The composition of sand changes depending on sample location. carbon dioxideCarbon dioxide is pure compound.diamondDiamonds are a form of elemental carbon.

Classification by Phase: Solid, Liquid, and Gas

Classification by Phase: Solid, Liquid, and Gas

Concept Check 1.3Classify a cup of grape juice in terms of its state and composition.

Concept Check 1.3 SolutionClassify a cup of grape juice in terms of its state and composition.State: At room temperature, a cup of grape juice is a liquid. If the liquid were cooled below 0C, a grape popsicle (solid) results.Composition: Grape juice is a clear purple liquid indicating a homogeneous solution of water with molecules that bring color (pigments) and sweetness (sugar). Included in this solution are vitamins and other nutrients.

Properties of MatterPhysical properties: those properties that a substance displays without changing its composition.

Chemical properties: those properties that a substance displays only when changing its composition.

Physical and Chemical PropertiesDifferentiating between physical and chemical properties (and/or changes) is NOT trivial for the inexperienced observer.The evaporation of alcohol is a physical change. The alcohol does not change composition upon vaporization.

Concept Check 1.4Classify the following as a physical change or a chemical change.Iron rustingsugar dissolving in waterpaper burning in airice melting

Concept Check 1.4 SolutionIron rusting is a chemical change. Elemental iron is converted to iron(III) oxide (rust) upon exposure to oxygen.Sugar dissolving in water is a physical change. Both the sugar and the water are unchanged by the process and can be separated into their pure form by evaporation of water.Paper burning is a chemical change. The paper is converted to carbon dioxide and water when ignited in the presence of oxygen.Ice melting is a physical change. Both ice and water are H2O, which is not altered by the phase change of a solid to a liquid.

Atomic Theory DevelopsLavoisier- Law of Conservation of MassMatter is neither created nor destroyed in a chemical reaction.Father of Modern ChemistryStudied combustion in closed containers

Proust Law of Constant CompositionAll samples of a compound have the same proportions of their constituent elements.

Concept Check 1.5Oxygen and hydrogen combine in a mass ratio of 8:1 respectively to form water (H2O). Hydrogen peroxide (H2O2) forms from the combination of 2.0 grams of hydrogen and 32 grams of oxygen.What is the mass ratio combination of oxygen to hydrogen in hydrogen peroxide?The combining oxygen to hydrogen mass ratio for water is different than that for hydrogen peroxide. Is this observation consistent with the law of constant composition?

Concept Check 1.5 Solution32 grams of oxygen combine with 2.0 grams of hydrogen to form 34 grams of H2O2.

Both hydrogen peroxide and water are composed of hydrogen and oxygen atoms. All water is composed of oxygen and hydrogen combined in a 8:1 mass ratio. All hydrogen peroxide is composed of oxygen and hydrogen combined in a 16:1 mass ratio. Even though they are composed of the same elements, they are different compounds. Both are following the law of constant composition.

Daltons Atomic TheoryAll matter is composed of particles called atoms.All atoms of a given element are alike in mass and other properties.Atoms differ from one element to another.Atoms of different elements combine to form compounds in simple whole number ratios.Daltons theory is synthesized from MANY different sources of information.

Rutherfords Nuclear TheoryGold Foil ExperimentDirected alpha particles at gold foilSome alpha particles were deflected by something in the atomDevised a theory to explain the experimental resultsDemonstrated that the nucleus consists of particles: positively charged protons and neutral neutrons

Rutherfords Nuclear TheoryMost of an atoms mass is contained in a small space called the nucleus.Most of an atoms volume is empty space occupied by very tiny negative charged particles called electrons.The number of negatively charged electrons outside of the nucleus is the same as the number of positively charged particles in the nucleus for electrically neutral atoms.

Rutherfords Nuclear TheoryThe graphite in pencil lead is made of carbon atoms.Each carbon atom consists of a nucleus surrounded by a diffuse cloud of electrons.The nucleus is composed of positively charged protons and neutral neutrons.

Concept Check 1.6A neutral carbon atom has six electrons outside the nucleus.How many protons must be in the nucleus?What other atomic particle is found in the nucleus of an atom other than protons?

Concept Check 1.6 SolutionA neutral carbon atom must have an equal number of protons and electrons, therefore, with six electrons outside the nucleus, there must be six protons in the nucleus.The other basic atomic particle found in the nucleus of an atom is the neutron, which is uncharged.

Chapter SummaryMolecular ConceptThe scientific methodClassifying matterJohn Daltons atomic theoryRutherfords Nuclear atomSocietal ImpactChemistry deepens our understanding of the world.Technology has grown and continues to grow as we apply the knowledge acquired through the scientific method.