Post on 01-Jan-2016
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