What’s the MATTER: Classify Changes of Matter

Matter, Classify Changes of Matter At the conclusion of our time together, you should be able to: Characterize various changes of matter Recognize that a change of state in matter is a physical change

Physical Change Physical A change in matter from one form to another without changing its chemical properties (most can be reversed) No change in atoms/molecules

Physical Change Examples = Change in state or phase change Dissolving Compressing Light emission/absorption Electrons passing through metals

Physical Change More Examples = boiling of a liquid melting of a solid dissolving a solid in a liquid to give a homogeneous mixture making a solution

Cl-1 Cl-1 2 Chemical Change 1 Chemical Li +1 Bonds are made / broken Change in oxidation states Li +1 Cl-1 Cl-1

Examples of Chemical Change Burning hydrogen (H2) in oxygen (O2) gives H2O. Chemical change or chemical reaction — transformation of one or more atoms or molecules into one or more different molecules.

Sure Signs of a Chemical Change “Chemists Get Practice Trying Labs” Color Change Gas Produced (not from boiling!) Precipitate – a solid formed by mixing two liquids together Temperature Change Light

Remember the Law of Conservation of Mass In a physical change or a chemical reaction, mass is neither created or destroyed (Antoine Lavoisier)

Matter, Classify Changes of Matter Let’s see if you can: Characterize various changes of matter Recognize that a change of state in matter is a physical change

Physical vs. Chemical Change Examples: melting flame produced paper cut dissolving salt in water tarnishes in air

Physical vs. Chemical Change Examples: rusting iron mixing mud and water burning a log freezing water grinding spices

A difference between physical change and chemical change is that chemical change involves energy while physical change does not. physical change involves energy while chemical change does not. different kinds of molecules are present after a physical change but not after a chemical change. different kinds of molecules are present after a chemical change but not after a physical change

In making a pizza, which process involves a chemical change? Mixing spices for the sauce Slicing pepperoni for the topping Spreading cheese on the pizza Baking the dough to form the crust

What’s the MATTER, Properties of Matter

Matter, Properties of Matter At the conclusion of our time together, you should be able to: Explain the difference between the extensive and intensive properties and other types of properties Distinguish between a physical property and chemical property

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

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

A Chemist’s View Macroscopic 2 H2(g) + O2 (g) --> 2 H2O(g) Symbolic Particulate

Properties of Matter 2 Types: Extensive – depend on the amount of the sample Always involves a number with unit Examples = volume mass length

Properties of Matter (cont.) Intensive – does not depend on the amount of the sample Usually does not involve a number Examples = density melting, boiling point malleability ductility color odor

Properties Every substance has a unique set of properties (characteristics that identify that substance) Physical Properties- Properties that can be measured without changing the identity and composition of the substance

Physical Property Examples- Color Odor Density Melting Point Boiling Point Hardness Solubility

List Some Physical Properties of: Graphite — this layer structure of carbon atoms reflects its physical properties.

Chemical Properties Properties that describe the way a substance may change to form other substances Only observed when a chemical reaction takes place

Chemical Property Examples Combustible Reactive with water or acid Flammable Corrosive Decomposes in air

Physical vs. Chemical Properties Physical Properties- Properties that can be measured without changing the identity and composition of the substance Chemical Properties- Properties that can be measured by changing the identity and composition of the substance

Matter, Properties of Matter Let’s see if you can: Explain the difference between the extensive and intensive properties and other types of properties Distinguish between a physical property and chemical property

Properties of Matter 2 Types: Extensive – depends on the amount of the sample Intensive – does not depend on the amount of the sample

Physical vs. Chemical Properties Physical Properties- Properties that can be measured without changing the identity and composition of the substance Chemical Properties- Properties that can be measured by changing the identity and composition of the substance

Physical vs. Chemical Property Examples: melts at 55oF flammable will tear easily will dissolve in water will tarnish

Physical vs. Chemical Properties Examples: will rust mixture can be separated by boiling burns freezes at -20oC can be crushed