Ch1 Matter & Measurement Flashcards
Property
Any characteristic that allows us to recognize a particular type of matter and to distinguish it from other types.
Element
A substance consisting of atoms of the same atomic number. A substance that cannot be separated into simpler substances by chemical means.
Atom
The smallest representative particle of an element.
Molecule
A chemical combination of two or more atoms.
Gas
No fixed volume or shape; uniformly fills its container. Can be compressed to occupy smaller space or expand for larger.
Liquid
Distinct volume independent of its container. Assumes shape of portion of container it occupies.
Solid
Definite shape and volume.
(Pure) Substance
Matter that has distinct properties and a composition that foes not vary from sample to sample.
Compounds
Substances composed of two or more elements; they contain two or more kinds of atoms.
Law of constant composition
Or
Law of definite proportions
Elemental composition of a compound is always the same.
Solution
Homogeneous mixture
Physical properties
Observed w/o changing the identity and composition of the substance.
Color, odor, density, melting point, boiling point, hardness.
Chemical properties
The way the substance may change or react to form other substances.
Flammability.
Intensive properties
Don’t depend on the amount of sample being examined and are particularly useful to identify substances.
Temperature and melting point
Extensive properties
Depend on the amount of sample.
Mass and volume
Physical change
Substance changes its physical appearance but not its composition.
W
Eg water evaporation
Chemical change/reaction
Substance is transformed into a chemically different substance.
Eg hydrogen burns in air–combines w/ oxygen to form water.
Distillation
Method of separating the components of a homogeneous mixture. A process that depends on the different abilities of substances to form gases.
Eg boil salt water– water evaporates and leaves salt behind.
Theory
A predictive model that accounts for all observations.
Scientific law
When nature behaves in a certain way over and over again, under all sorts of conditions.
SI Base Units
Mass-kilogram-kg Length-meter-m Time-second-s or sec Temperature-kelvin-K Amount of substance-Mole-mol Electric Current-ampere- A or amp Luminous intensity-Candela-cd
Matter
The physical material of the universe; has mass and occupies space.
Temperature
Measure of hotness or coldness of an object, is a physical property that determines the direction of heat flow.
Celsius scale
0 degrees C – freezing point of water.
100 degrees C – boiling point at sea level.
Absolute zero
Zero on the kelvin scale– -237.15 degrees C
Kelvin and Celsius relation
K = degreeC + 273.15
Freezing point of water 0 degree C is 273.15K
Fahrenheit to Celsius Formula
C = 5/9 (F - 32)
Celsius to Fahrenheit Formula
F = 9/5 (C) + 32
Derived unit
Obtained by multiplication or division of one or more base units.
Precision
Measure of how closely individual measurements agree with one another.
Accuracy
How closely individuals measurements agree with the correct or “true” value.
Significant figures in calculations:
Addition and subtraction
&
Multiplication and division
The result has the same number of decimal places a the measurement with the fewest decimal places.
&
The result contains the same # of significant figures as the measurement with te fewest significant figures.
Dimensional analysis
Units are multiplied together or divided into each other along with the numerical values.
Conversion factor
Fraction whose numerator and denominator are the same quantity expressed in different units. Eg 2.54 cm = 1 in. # of cm = (8.50 in.) 2.54 cm/1 xin.x = 22.6 cm
