I. Density
Matter has Mass & Volume
- Matter- Anything that has mass and takes up space
- The space an object occupies is its volume
- Volume—a measure of the size of a body or region in three-dimensional space
- The method used to determine volume depends on the nature of the matter being examined
Quantity of Matter is Mass
- Mass- a measure of the amount of matter in an object. It is not affected by the gravitational force
- Balances measure mass usually in grams
- It is the same no matter where it is in the universe
Mass is NOT Weight
- Weight- the force produced by gravity action on mass
- Its value can change with the location of the object in the universe
- Measured in Newtons
II. Units of Measurement
- Mass & volume are properties that can be described in terms of numbers
- Numbers alone aren’t enough because their meaning might be unclear
- Units of measurement are needed with the numbers
Quantity- something that has magnitude, size, or amount
Unit- a quantity adopted as a standard of measurement
- System Internationale d’Units
- Seven base units
- Base units can be modified by attaching prefixes
Derived Units
- Many quantities you can measure need units other than the seven basic SI Units
- These units are derived by multiplying or dividing the base units
Properties of Matter
Properties of substances may be classified as physical or chemical
Physical Properties
- Characteristic of a substance that doesn’t involve a chemical change, such as density, color, or hardness
Chemical Properties
- A property of matter that describes a substance’s ability to participate in chemical reactions
- Examples: reactivity with oxygen, sensitivity to light, exposure to heat
Density
- Density- the ratio of mass to volume of a substance. Often expressed in grams/cm3 for solids and liquids and g/L for gases
Density= mass/volume or D=m/v
Classifying Matter
-From the last section:
-Matter-anything that has mass and takes up space
-All matter is composed of Atoms
-Atom- the smallest unit of an element that maintains the properties of that element
Because matter exists in so many different forms, having a way to classify it is important for study.
It helps you to predict what characteristics a sample will have based on what you know about others like it.
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