Matter And Energy Chemistry I: Chapter 2a Chemistry I Honors: Chapter 2 ICP: Chapter 15 & 16a SAVE PAPER AND INK!!! When you print out the notes on PowerPoint, print "Handouts" instead of "Slides" in the print setup. Also, turn off the backgrounds (Tools>Options>Print>UNcheck "Background Printing")!

The Nature of Matter Chemists are interested in the nature of matter and how this is related to its atoms and molecules. GoldMercury

Chemistry & Matter We can explore the MACROSCOPIC world — what we can see —We can explore the MACROSCOPIC world — what we can see — to understand the PARTICULATE worlds we cannot see.to understand the PARTICULATE worlds we cannot see. We write SYMBOLS to describe these worlds.We write SYMBOLS to describe these worlds.

A Chemist’s View of Water H 2 O (gas, liquid, solid) MacroscopicMacroscopic SymbolicSymbolic ParticulateParticulate

A Chemist’s View 2 H 2 (g) + O 2 (g) --> 2 H 2 O(g) MacroscopicMacroscopic SymbolicSymbolic ParticulateParticulate

Kinetic Nature of Matter Matter consists of atoms and molecules in _____.

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

OTHER STATES OF MATTER PLASMA — an electrically charged gas; Example: the sun or any other starPLASMA — an electrically charged gas; Example: the sun or any other star BOSE-EINSTEIN CONDENSATE — a condensate that forms near absolute zero that has superconductive properties; Example: supercooled Rb gasBOSE-EINSTEIN CONDENSATE — a condensate that forms near absolute zero that has superconductive properties; Example: supercooled Rb gas

Physical Properties What are some physical properties? colorcolor melting and boiling pointmelting and boiling point OdorOdor Anything you can touch, see, hear, taste…Anything you can touch, see, hear, taste…

Extensive vs. intensive property Extensive properties are dependent upon the amount of substance present. Ex- mass, length Intensive property is independent of the amount of substance present. Ex- density, temperature

Graphite — layer structure of carbon atoms reflects physical properties.

Physical Changes –can be observed without changing the identity of the substance Some physical changes would be boiling of a liquidboiling of a liquid melting of a solidmelting of a solid dissolving a solid in a liquid to give a homogeneous mixture — a SOLUTION.dissolving a solid in a liquid to give a homogeneous mixture — a SOLUTION.

Chemical Properties and Chemical Change Chemical properties cannot be seen- reactivity, flammability, corrosiveness.Chemical properties cannot be seen- reactivity, flammability, corrosiveness. Burning hydrogen (H 2 ) in oxygen (O 2 ) gives H 2 O.Burning hydrogen (H 2 ) in oxygen (O 2 ) gives H 2 O.

Chemical Properties and Chemical Change Chemical change or chemical reaction — transformation of one or more atoms or molecules into one or more different molecules.Chemical change or chemical reaction — transformation of one or more atoms or molecules into one or more different molecules. Burning hydrogen (H 2 ) in oxygen (O 2 ) gives H 2 O.Burning hydrogen (H 2 ) in oxygen (O 2 ) gives H 2 O.

Sure Signs of a Chemical Change HeatHeat LightLight Gas Produced (not from boiling!)Gas Produced (not from boiling!) Precipitate – a solid formed by mixing two liquids togetherPrecipitate – a solid formed by mixing two liquids together Law of conservation of mass- Matter is neither created nor destroyed during a chemical reaction.Law of conservation of mass- Matter is neither created nor destroyed during a chemical reaction.

Physical vs. Chemical Examples: –melting point –flammable –density –magnetic –tarnishes in air physical chemical physical chemical

Physical vs. Chemical Examples: –rusting iron –dissolving in water –burning a log –melting ice –grinding spices

Matter Flowchart MATTER Can it be physically separated? Homogeneous Mixture (solution) Heterogeneous MixtureCompound MIXTUREPURE SUBSTANCE yesno Can it be chemically decomposed? noyes Is the composition uniform? noyes ColloidsSuspensions Element

Types of Mixtures Variable combination of 2 or more pure substances. Heterogeneous – visibly separate phases Homogeneous – Same throughout

Methods of separation Filtration- use filter paper to separate based on particle size Distillation- boil off liquids at different temperatures Crystallization- separate based on formation of crystals Sublimation- solids going directly to gases.opposite- deposition. Chromatography- liquids rise up in a column based on affinity Do Chromatography lab

Practice 1. Which of the following is NOT matter? (1) a chair (2) air (3) light (4) water 2. Which of the following is NOT a property of matter? (1) inertia (2)occupies space (3) composed of elements (4) weightlessness 3. Which of the following may be heterogeneous? (1) elements only (2) compounds only (3) mixtures only (4) elements and compounds 4. Which of the following is pure? (1) elements only (2) compounds only (3) mixtures only (4) elements and compounds 5. Which of the following consists of more than one substance? (1) elements only (2) compounds only (3) mixtures only (4) elements and compounds

Practice (contd). 6. Which of the following are types of matter? (1) elements only (2) compounds only (3) mixtures only (4) all of these 7. Which of the following is a type of mixture? (1) elements only(2) compounds only (3) solutions only (4) elements and Compounds 8. Which of the following is NOT composed of two or more types of atoms? (1) element (2) compound (3) solution (4) mechanical mixture 9. Which represents a homogeneous mixture? (1) CuSO4(s) (2) NaCl(aq) (3) Br2(R) (4) CO2(g) 10. Which substance can be decomposed by a chemical change? (1) ammonia (2) iron (3) argon (4) helium

Elements and compounds Elements- simplest form of matter Compounds formed by combining elements in a fixed ratio. Periodic table- organizes elements into groups (families) and periods. Groups are vertical and periods are horizontal Law of definite proportions- Any compound is always composed of same elements in same proportion. Ex- CuF2= 1 Cu 2F Percent by mass=mass of element/ mass of compound x100. P88 Practice problems- q19-22

Law of multiple proportions Compounds can be formed in more than one way between two or more elements. Elements can combine in different proportions with whole number ratios when this happens. Ex- H2O and H2O2