Science Notes
The States of Matter (Notes on the left)
Identifying properties and changes Notes
Physical properties can be observed or measured without changing the composition of matter. Physical properties are used to observe and describe matter.
Physical properties include: appearance, texture, color, odor, melting point, boiling point, density, solubility, polarity, and many others.
The three states of matter are: solid, liquid, and gas. The melting point and boiling point are related to changes of the state of matter. All matter may exist in any of three physical states of matter
A physical change takes place without any changes in molecular composition. The same element or compound is present before and after the change. The same molecule is present through out the changes. Physical changes are related to physical properties since some measurements require that changes be made.
Melting Point: As solid matter is heated it eventually melts or changes into a liquid state at the melting point.
Ice (a solid form of water) melts at 0 oC and changes to the liquid state.
Carbon dioxide melts at -56.6oC
Boiling Point: As the liquid matter is heated further it eventually boils or vaporizes into a gas at the boiling point.
Liquid water boils and changes into a gas, usually called steam or water vapor at 100 oC. In all three states the same molecules of water (H2O) are present.
Carbon dioxide boils at -78.5oC
Chemical properties of matter describes its "potential" to undergo some chemical change or reaction by virtue of its composition. What elements, electrons, and bonding are present to give the potential for chemical change.
It is quite difficult to define a chemical property without using the word "change". Eventually you should be able to look at the formula of a compound and state some chemical property. At this time this is very difficult to do and you are not expected to be able to do it.
For example hydrogen has the potential to ignite and explode given the right conditions. This is a chemical property.
Metals in general have they chemical property of reacting with an acid. Zinc reacts with hydrochloric acid to produce hydrogen gas. This is a chemical property
Chemical change results in one or more substances of entirely different composition from the original substances. The elements and/or compounds at the start of the reaction are rearranged into new product compounds or elements.
A CHEMICAL CHANGE alters the composition of the original matter. Different elements or compounds are present at the end of the chemical change. The atoms in compounds are rearranged to make new and different compounds.
Magnesium reacts with oxygen from the air producing an extremely bright flame. This is a chemical change since magnesium oxide has completely different properties than magnesium metal shown on the left.
The atoms are rearranged - diatomic oxygen molecules are split apart so that one oxygen atom combines with one magnesium atom
LAB Work
Density Lab This will give you all the information that you need to complete the density lab and understand the concept of density.
Cooking with Chemistry