DESCRIBING MATTER. Matter is anything that has mass and volume

Transcription

1 DESCRIBING MATTER Matter is anything that has mass and volume

2 Mass the amount of matter in an object measured with a balance Units are grams, kilograms (SI), centigrams Weight the measurement of gravitational force on an object measured with a scale Units are newtons Volume the amount of space occupied by an object measured with a ruler for regular shaped objects or a graduated cylinder for liquids units are cubic length units or liters, milliliters, etc.

3 Units of Measure a qualitative description uses words such as tall, light, small, rough to describe matter quantity - something that has magnitude or size like volume or mass unit - an amount that has been accepted as a standard like meter, gram, or liter SI units (international system) used by scientists all over the world to make measurements. consists mostly of the metric system. 7 base units luminous intensity - candela *length- meters *temperature - kelvin *mass - kilogram *amount of substance - mole *time - second electric current - ampere

4 Conversion Factors - used to convert from one unit to another. Convert 3.8 mg to g Identify the quantity and unit give: 3.8 mg use the fraction that has the given unit on the bottom and the unit you are converting to on the top: g/mg assign the larger unit the value of :1g the smaller unit then is given a value based on its prefix: m = 1/1000 therefore it takes 1000 mg to make a g so your conversion factor is 1g/1000mg. multiply the given value time the conversion factor, just like you would any other fraction. 3.8mg x 1g/1000mg. the mg cancel out and you are left with g

5 Derived Units - units that are derived through some calculation of the 7 base units for example the volume of a 2 cm square cube is 2cm x 2cm x 2cm or 8cm 3 this is a derived unit because we multiplied the base units to come up with a cubic centimeter. A cubic centimeter is equal to a milliliter. A cube 1cm on each side will contain exactly one milliliter of liquid. This is an important fact to remember! Other derived units are used to measure: area, density, speed,

6 Properties of matter - used to describe matter can be either physical or chemical Physical properties - properties that can be measured or observed without changing the identity of the substance. mass, length, color, texture, taste, odor, these are all physical properties Density is a physical property that describes the mass of an object in relationship to its volume. formula: density = mass/volume or d = m/v the graph of a substances mass and volume is a straight line because the density remains constant for a substance. a graph that results in a straight line represents a direct relationship. when one variable increases or decreases so does the other. Density is a characteristic property that can be used to identify a substance, it will never change for that substance.

7 Chemical Properties Describes how a substance interacts with other substances. in the presence of oxygen iron will react to form the compound iron oxide (rust) gold does not react readily with oxygen is also a chemical property other chemical properties are: flamibility combustibility reactivity with acids