What’s the Matter

Chemistry is the study of matter and the transformations it can undergo…

…. Matter is anything that occupies space.

Guiding Questions Why do substances boil or freeze at different temperatures? Why do we put salt on the roads in the winter? What properties of diamonds make them useful in a variety of applications?

Classification of Matter Scientists classify or group materials based on different characteristics. Matter can be classified according to whether it is a mixture or a pure substance.

MATTER Can it be physically separated? Homogeneous Mixture (solution) Heterogeneous MixtureCompoundElement MIXTUREPURE SUBSTANCE yesno Can it be chemically decomposed? noyes Is the composition uniform? noyes ColloidsSuspensions Courtesy Christy Johannesson

Particle Theory of Matter All matter is made up of tiny particles Each pure substance has its own kind of particle, which is different from the particles of other pure substances. Particles attract each other Particles are always moving. Particles at a higher temperature move faster, on average, than particles at a lower temperature.

Pure Substances Contain only one kind of particle. e.g. water, oxygen gas, chlorine gas, sodium metal. Can be classified into two main groups: elements and compounds. Sulphur on the left is composed of one type of atom, and water on the right is made up of a compound, with 1 type of molecule (2 hydrogen and 1 oxygen atom).

Pure Substances Element –composed of identical atoms –EX: copper wire, aluminum foil Courtesy Christy Johannesson

Pure Substances Compound –composed of 2 or more elements in a fixed ratio –properties differ from those of individual elements –EX: table salt (NaCl) Courtesy Christy Johannesson

Pure Substances Law of Definite Composition –A given compound always contains the same, fixed ratio of elements. Law of Multiple Proportions –Elements can combine in different ratios to form different compounds. Courtesy Christy Johannesson

Pure Substances For example… Two different compounds, each has a definite composition. Carbon, C Oxygen, O Carbon monoxide, CO Carbon, C Oxygen, O Oxygen, O Carbon dioxide, CO 2 Courtesy Christy Johannesson

Elements – A Pure Substance Cannot be broken down further by chemical or physical methods. Elements are organized into the periodic table based on similar properties. Copper is an element – a pure substance

Compounds – A Pure Substance Is made of two or more different elements that are chemically compound. Water is a compound made of the elements hydrogen and oxygen. Can be broken down into its elements by chemical methods. Water can be broken down into hydrogen and oxygen by electrolysis Sodium Chloride NaCl – a compound (Salt)

Mixtures Contain more than one kind of particle. Salt water is a mixture of salt dissolved in water. Air is a mixture of gases that include nitrogen, oxygen and carbon dioxide. A granite rock is a heterogeneous mixture. Notice the different visible parts (minerals).

Mixtures Variable combination of two or more pure substances. Contain more than one particle. HeterogeneousHomogeneous Courtesy Christy Johannesson

Mixtures Solution –homogeneous –very small particles –particles don’t settle –EX: rubbing alcohol Courtesy Christy Johannesson

Mixtures Colloid –heterogeneous –medium-sized particles –particles don’t settle –EX: milk Courtesy Christy Johannesson

Mixtures Suspension –heterogeneous –large particles –particles settle –EX: fresh-squeezed lemonade Courtesy Christy Johannesson

Matter Flowchart Examples: –graphite –pepper –sugar (sucrose) –paint –soda Courtesy Christy Johannesson element heterogenous mixture compound solution Homogenous mixture heterogenous mixture

Mixtures Examples: –mayonnaise –muddy water –fog –saltwater –Italian salad dressing Courtesy Christy Johannesson colloid suspension colloid solution suspension

Classification of Matter Materials Homogeneous Heterogeneous mixture Homogeneous mixture Substance ElementCompoundSolutionMixture Specific / General Order / Disorder Smoot, Smith, Price, Chemistry A Modern Course, 1990, page 43

Classification of Matter MATTER (gas. Liquid, solid, plasma) PURE SUBSTANCES MIXTURES HETEROGENEOUS MIXTURE HOMOGENEOUS MIXTURES ELEMENTSCOMPOUNDS Separated by physical means into Separated by chemical means into Kotz & Treichel, Chemistry & Chemical Reactivity, 3 rd Edition, 1996, page 31

Elements, Compounds, and Mixtures (a) an element (hydrogen) (b) a compound (water) (c) a mixture (hydrogen and oxygen) (d) a mixture (hydrogen and oxygen) Dorin, Demmin, Gabel, Chemistry The Study of Matter, 3 rd Edition, 1990, page 68 hydrogen atoms hydrogen atoms oxygen atoms

Elements, Compounds, and Mixtures (a) an element (hydrogen) (b) a compound (water) (c) a mixture (hydrogen and oxygen) (d) a mixture (hydrogen and oxygen) Dorin, Demmin, Gabel, Chemistry The Study of Matter, 3 rd Edition, 1990, page 68 hydrogen atoms hydrogen atoms oxygen atoms

Mixture vs. Compound Mixture Fixed Composition Bonds between components Can ONLY be separated by chemical means Variable Composition No bonds between components Can be separated by physical means Alike Different Contain two or more elements Can be separated into elements Involve substances Compound Different Topic

Compounds vs. Mixtures Compounds have properties that are uniquely different from the elements from which they are made. –A formula can always be written for a compound –e.g. NaCl  Na + Cl 2 Mixtures retain their individual properties. –e.g. Salt water is salty and wet

Separating Mixtures A filter can separate solids from liquids or gases. Distillation can separate liquids in a mixture based on boiling point by vapourization, condensation. Magnets will attract iron and steel objects.

Methods of Separating Mixtures Magnet Filter Decant Evaporation Centrifuge Chromatography Distillation

Filtration separates a liquid from a solid Zumdahl, Zumdahl, DeCoste, World of Chemistry  2002, page 40 Mixture of solid and liquid Stirring rod Filtrate (liquid component of the mixture) Filter paper traps solid Funnel

Chromatography Tie-dye t-shirt Black pen ink DNA testing –Tomb of Unknown Soldiers –Crime scene –Paternity testing

Setup to heat a solution Zumdahl, Zumdahl, DeCoste, World of Chemistry  2002, page 42 Ring stand Beaker Wire gauze Ring Bunsen burner

A Distillation Apparatus liquid with a solid dissolved in it thermometer condenser tube distilling flask pure liquid receiving flask hose connected to cold water faucet Dorin, Demmin, Gabel, Chemistry The Study of Matter, 3 rd Edition, 1990, page 282

Cooling water out Cooling water in Run hose into sink Connect hose to cold water tap

The solution is boiled and steam is driven off. Zumdahl, Zumdahl, DeCoste, World of Chemistry  2002, page 39

Salt remains after all water is boiled off. Zumdahl, Zumdahl, DeCoste, World of Chemistry  2002, page 39

No chemical change occurs when salt water is distilled. Zumdahl, Zumdahl, DeCoste, World of Chemistry  2002, page 40 Saltwater solution (homogeneous mixture) Distillation (physical method) Salt Pure water

Separation of a sand-saltwater mixture. Zumdahl, Zumdahl, DeCoste, World of Chemistry  2002, page 40

Separation of Sand from Salt 1.Gently break up your salt-crusted sand with a plastic spoon. Follow this flowchart to make a complete separation. Salt- crusted sand. Dry sand. Wet sand. Weigh the mixture. Decant clear liquid. Evaporate to dryness. Pour into heat-resistant container. Fill with water. Stir and let settle 1 minute. Weigh sand. Calculate weight of salt. Repeat 3 times? Yes No 2.How does this flow chart insure a complete separation?

Centrifugation Spin sample very rapidly: denser materials go to bottom (outside) Separate blood into serum and plasma –Serum (clear) –Plasma (contains red blood cells ‘RBCs’) Check for anemia (lack of iron) Blood RBC’s Serum A B C AFTER Before

The decomposition of two water molecules. 2 H 2 O  O H2H2 Electric current Water molecules Diatomic oxygen molecule hydrogen molecules +

Electrolysis *Must add acid catalyst to conduct electricity *H 1+ water oxygen hydrogen “electro” = electricity “lysis” = to split Zumdahl, Zumdahl, DeCoste, World of Chemistry  2002, page 32 Water Hydrogen gas forms Oxygen gas forms ElectrodeSource of direct current H 2 O(l) O 2 (g) + 2 H 2 (g)

Electrolysis of Water Half reaction at the cathode (reduction): 4 H 2 O + 4 e -  2 H OH 1- Half reaction at the anode (oxidation): 2 H 2 O  O H e - hydrogen gas cathode oxygen gas anode D.C. power source water

Advantages and Disadvantages Elements and compounds have positive effects on society such as making our lives healthier and safer. Negative consequences – toxic chemicals that are used to produce in the manufacture or isolation of certain elements and compounds can be released into the environment and cause bioaccumulation. Frog with three legs due to chemical exposure.

ELEMENT hydrogen molecule, H 2 ELEMENT oxygen molecule, O 2 MIXTURE a mixture of hydrogen and oxygen molecules CHEMICAL REACTION if molecules collide with enough force to break them into atoms, a can take place COMPOUND water, H 2 O

ELEMENT hydrogen molecule, H 2 ELEMENT oxygen molecule, O 2 MIXTURE a mixture of hydrogen and oxygen molecules CHEMICAL REACTION if molecules collide with enough force to break them into atoms, a can take place COMPOUND water, H 2 O

2 H 2 O2O2 O2O2 2 H 2 O E E Copyright © 2007 Pearson Benjamin Cummings. All rights reserved.

The Zeppelin LZ 129 Hindenburg catching fire on May 6, 1937 at Lakehurst Naval Air Station in New Jersey.

S.S. Hindenburg 35 people died when the Hindenburg exploded. May 1937 at Lakehurst, New Jersey German zeppelin luxury liner Exploded on maiden voyage Filled with hydrogen gas

Reviewing Concepts Reviewing Concepts Classifying Matter Why does every sample of a given substance have the same properties? Explain why the composition of an element is fixed. Describe the composition of a compound. Why can the properties of a mixture vary? On what basis can mixtures be classified as solutions, suspensions, or colloids? Name two processes used to separate mixtures?