Matter And Energy

Medical Chemistry Lecture By : Asst. Lect. Tariq Al Mgheer
College of Medicine- Babylon University
Matter And Energy
Matter define as anything that has mass and occupies space.
PROPERTIES OF MATTER -
A particular kind of matter, such as water, gold, silver, salt, or sugar, is called a substance. Every substance has a characteristic set of properties that makes it different from all other substances. These properties give it a unique identity. For example, sugar is an odorless, white solid that has a sweet taste. When heated, sugar melts and turns brown. The properties of a substance that are characteristic of that substance are called its intrinsic properties. The^e properties do ,".ot depend on the size or shape of the substance.
Some intrinsic properties are more uSefU ihan others in describing matter, such as melting, boiling points and densities. They are easily measured and expressed in numbers, it is give numerical values. For example th© specific pi-operties of water are its boiling point (100° C), melting point (0° C), and density (1.0 g/rnL at 4°C). No other substance has exactly this set of properties These intrinsic properties are called physical properties.
Many substances react, either alone or with other matter, to form new materials. These reactions are called tne chemical prop srties of a substance. CLSSIFYING MATTER
Matter is ciassified as either a mixture or a pure substance. A mixture contains a number of different substances mixed together. A mixture has no unique set of properties. Rather, it has the properties of a!! the substances that are a part of it.
A mixture is either heterogeneous or homogeneous. The parts of a heterogeneous mixture ;re visibly different, and the parts of a homogeneous mixture cannot be detected even with a microscope.
A mi/ture can be separated into its parts by using the differences in the physical properties of the parts. For exampic, when the temperature of air is lowered, water vapor separates as liquid (rain) or solid water (snow). When the air is cooled still further solid carbon dioxide (dry ice) form. Finally, ^ oven lower temperatures, the rest of the air becomes liquid. Thus, the differences in the physical properties of the substances in the mixture allow us to separate them
Pure substances are classified as either elements or compounds. COMPOSITION OF MATTER
Atoms are ^:» fundamental units of l.llerrlerlts. An element is a substance that contains only one kind of atom. Today, there are only 106 elements.