1-2 Describing Matter

MATTER

• anything that has mass and volume

VOLUME

• the space an object occupies• meas. in diff. ways

• graduated cylinder can be used to meas. liquid vol.• - read level @ bottom of meniscus

• Some solids – use length x width x height

MASS

• the quantity of matter in an object

• Does not vary w/ location• meas. using a balance – electronic or mechanical• usually meas. in grams or kilograms• diff. balances may give readings w/ diff. precision

• - the more decimal places, the more precise

WEIGHT

• the force produced by gravity acting on a mass• diff. from mass• meas. in newtons• can vary from place to place• meas. using a scale• Proportional to mass

QUALITATIVE DESCRIPTIONS

• describe matter using words• light• heavy• small• large• blue• hot

QUANTITATIVE DESCRIPTIONS

• describe matter using numbers with units• 35 lbs.• 15 grams• 18 km• 20 oC

QUANTITY

• something that has magnitude or size

UNIT

• a standard used when measuring a quantity (label)

• Measurements must contain both a quantity (number) and a unit.

SI system (formerly metric system) uses 7 basic quantities

to meas. everything (p. 12)

• Learn first 5 quantities, symbols, units, and abbreviations.

Base units can be modified with prefixes to make them larger or

smaller• Mass of dime meas. in grams

• diameter meas. in cm or mm• thickness meas. in mm or m

Learn the table on p. 13

• Add the following prefixes:• Mega – M – 106 – 1,000,000

• 1 megameter (Mm) = 1,000,000m

• Giga - G - 109 - 1,000,000,000• 1 gigameter (Gm) = 1,000,000,000 m

Learn the table on p. 13

• Add the following prefixes:• micro – – 10-6 – 1/1,000,000

• 1 micrometer (m) = 0.000 001m

• nano – n – 10-9 – 1/1,000,000,000• 1 nanometer (nm) = 0.000 000 001m

CONVERSION FACTOR

• mathematical expression that relates two units• used to convert metric units

Easiest method

• always put a 1 w/ the largest unit. The other unit will always be some positive power of 10

Examples: Convert the following

15 kg = g

7.75 m = km

48.7 mg = hg

DERIVED UNITS• units created from combinations of the seven base

units.• volume = length x width x height

• dm x dm x dm = dm3

• 1 dm3 = 1 liter = 1000 ml = 1000 cm3

• liter and ml are most common units for volume• newton = kg x m/s2

• energy (kinetic) = 1/2 x mass x velocity2 = kg x m2/s2

DENSITY

• the ratio of mass to volume• D = m/v• On a graph of mass vs. vol. The graph is a

straight line• -slope is the density

• density for any substance is constant and can be used to identify substs.

PHYSICAL PROPERTY• any property of matter that can be measured without

changing its chemical nature• color• mass• volume• density• boiling point

PHYSICAL CHANGE

• a change that affects only physical properties• boiling• breaking• painting• freezing

CHEMICAL PROPERTY

• a property of matter that can only be identified by trying to cause a chemical change• reacts w/ oxygen• reacts w/ water• does not react w/ water• decomposes