1-2 describing matter - cchs chemistry · 2018. 9. 9. · matter • anything that has mass and...
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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. 74)
• 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 µm
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. 75 • Add the following prefixes: • micro – µ – 10-6 – 1/1,000,000
• 1 micrometer (µm) = 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