Chemical and Physical Properties of Matter Part 1

What are properties? Matter has observable and measurable qualities. We can use general properties to identify substances. Two basic types of properties of matter: Physical properties and Chemical properties:

Properties are… Words that describe matter (adjectives) Physical Properties- a property that can be observed and measured without changing the material’s composition. Seen through direct observation Examples- color, hardness, density

Chemical Properties- a property that can only be observed by changing the composition of the material through a chemical change or reaction Examples- ability to burn, decompose, ferment, react with, etc.

List of Physical Properties Phase –state of matter at room temperature(solid, liquid, gas) Melting/Freezing point —temp at which a substances changes from a solid to liquid or liquid to solid Boiling/Condensation point —temp at which substances changes from a liquid to gas or gas to liquid

Color –way an object absorbs or reflects light Hardness – is the ability for an object to resist being scratched (harder object will scratch a softer one) Luster – shininess of a material Brittleness—the ease at which something will break Malleability – property of most metals, how easily rolled into sheets or bent into shapes

Solubility: the ability to dissolve in another substance Ductility: the ability to be drawn into wires(most metals) Density: mass per unit of volume Viscosity : how easily the substance will flow

List of Chemical Properties Flammability/Combustion: the ability of a substance to burn or ignite, causing fire or combustion. Reactivity: does it combine chemically with another substance Oxidation/Rusting: is the process when oxygen combines with a substance changing it in appearance or makeup PH: pH is a numeric scale used to specify the acidity or basicity of a substance

Part 2 Chemical and Physical Changes

Physical vs. Chemical Change Physical change will change the visible appearance, without changing the composition of the material. Boil, melt, cut, bend, split, crack Is boiled water still water? Can be reversible, or irreversible

Physical Changes

Physical Changes EX: Boiling Water would be: Physical only The steam is still H2O it is in a different state of matter, but it is still the same type of matter chemically!!! melting

Indicators of a Physical Change change in size, shape, state or creates a mixture. You still have the same material.

Chemical Changes Chemical change - a change where a new form of matter is formed. Rust, burn, decompose, ferment The ability of a substance to undergo a specific chemical change is called a chemical property. Ex. iron plus oxygen forms rust, so the ability to rust is a chemical property of iron During a chemical change (also called chemical reaction), the composition of matter always changes.

Chemical Reactions are… When one or more substances are changed into new substances. Reactants- the stuff you start with Products- what you make The products will have NEW PROPERTIES different from the reactants you started with Arrow points from the reactants to the new products

Examples of Chemical Changes Cooking an egg Metal rusting Baking a cake Fireworks Light Stick

Recognizing Chemical Changes Energy is absorbed or released (temperature changes hotter or colder) Color changes Gas production (bubbling, fizzing, change; smoke) Sound or change in odor formation of a precipitate - a solid that separates from solution (won’t dissolve) Irreversibility - not easily reversed But, there are examples of these that are not chemical – boiling water bubbles, etc.

Chemicals React and produce heat. (Exothermic reaction) Because heat is released when these chemicals mix together, you feel it as hot.

Chemicals React and absorb heat from the environment. (Endothermic) Because heat is absorbed when these chemicals mix together. You feel the coolness.

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