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