Matter And Energy

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

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 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 Heat/LightHeat/Light Color changeColor change OdorOdor 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 ft/CCA/CCA0/MOVIES/S1047.MOV

Physical vs. Chemical Properties 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

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

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