Chapter 1 Study Of Chemistry Flashcards
Matter:
Anything that has mass and occupies space. Made of atoms-the smallest particle of an element that retains chemical nature of the element.
Molecules
Two or more atoms chemically joined
The scientific Method
Observations
Hypothesis: a tentative explanation or interpretation. Must be testable.
Experiment: highly controlled set of procedures to generate more data or observations.
Scientific law:
Generalization about past observations from which future predictions can be made.
Examples:
Law of gravity/law of conversation of matter/ Newton’s law is motion/ law of thermodynamics
Scientific Theory:
An explanation of an observation or law. Theories can only be validated. Never prove a theory 100%.
Examples:
Theory of gravity/ Evolutionary Theory/ Big Bang Theory/ Cell theory
Measurements: international system d’unites
Length: meter,m Mass: kilograms, kg Time: seconds, s Temperature: kelvin, k Amount: mole, mol
Derived units
Volume
Density
Velocity
Force
Length
Distance traveled by light in a vacuum in a give time period.
1m=39.37 in
Volume
Amount of space occupied by an object
SI Unit: 1m^3= 1000L
1mL=1cm^3=1cc
Mass
The amount of matter in an object kilogram
Weight
A measure of the gravitational pull exact on an object
1kg=2.205lbs
Density
Mass/volume
Examples
g/cm^3=g/ml
Kg/L
Time
Cs-133 frequency of the emitted radiation
Temperature
A measure of the average kinetic energy in a system. Energy of motion.
Significant figures
Digits in a measurements which contain digits and one digit of uncertainty
Digital instruments
Record all digits shown on the display
Analog instruments
10% rule: in reading measurements the uncertainty should be 10% of the instrument increments
Buret
Glassware used to measure delivered volume
Rules of sig. figs.
- All non zeros are significant
- Zeros between no zeros are significant
- Leading zeros are never significant
- Trailing zeros right of a decimal are significant
- Trailing zeros before an implied decimal are not significant
- Counting numbers and define numbers have an infinite number of sig. dig. (No uncertainty)
Scientific notation
A way of expressing numbers as a number between 1 and 10 times 10 raised to some power
Positive exponent: large number- move decimal to right
Negative exponent: small numbers- move decimal to left
Metric prefixes
Kilo, k:1000 Centi, c:0.01 Milli, m:0.001 Micro, μ: 0.000001 Nano, n:0.000000001
Division/multiplication
The answer cannot have more sig. figs. Then any of the original numbers
Choose the smallest
Addition/subtraction
The answer cannot have more digits after the furthest left uncertain digit of any of the original numbers
Precision
How close a set of data are to each other reproducibility
Accuracy
How close a measurement is to the true or accepted value
Error
The difference between an experimental value and the true value
Gross(human)
Error that arises from carelessness, laziness, bad luck, etc
Random(indeterminate)
An inherent error present in all measurements that has equal probability for being too high or too low
Systematic(determinate)
An error that is bias in a particular direction and has an assignable cause
Conversion factors
1ft: 12in
1km: 1000m
1hr: 3600s
50mi: 1hr
Solid
Low kinetic energy. Strong attractive forces.
Fix volume, fixed shape
Liquid
Moderate kinetic energy. Moderate attractive forces
No fix shape, fixed volume
Gas
High kinetic energy. No attractive forces
No fix volume, no fix shape
Liquid and gas
Liquid to gas: evaporation
Gas to liquid: condensation
Liquid and solid
Liquid to solid: freezing
Solid to liquid: melting/fusion
Gas and solid
Gas to solid: deposition
Solid to gas: sublimation
Pure substances
Matter that has a fixed composition
Element
Simplest type of matter with uniques properties comprised of a single type of atom
Compounds
Matter that is composed of two or more types of atoms that are chemically bond
Mixture
Matter comprises of two or more types of pure substance
Homogenous
Matter that has uniform composition throughout
Heterogenous
Matter that has a voguing composition
Distillation
Separation based on different boiling points
Filtration
Separation based on passing the sample through a medium that selectively retains certain particles
Magnetism
Separation based on magnetic particles
Centrifugation
Separation of solids from liquids
Chromatography
Separation based on an analyses affinity for a stationary phase vs mobile phase
Physical properties
Characteristics that can be observed without changing the substance
Chemical properties
Characteristics that can only be observed by reacting the substance
Flammable, water reactive
Physical change
Change that alters the state(solid,liquid,gas) or physical property
Chemical change
Change that alters chemical make-up of a substance
Intensive property
Characteristics that is independent of the amount of matter present
Boiling, density
Extensive property
Characteristics that is dependent of the amount of matter present
Volume and mass
