Chapter 1 Flashcards
What are two-atom molecules called?
Diatomic
Matter consists of __ __. The world we know is called the __ world. World of atoms and molecules is called the __ world. Substances result from about __ different atoms
Individual atomsMacroscopicMicroscopic100
Steps in the scientific method (3)
1) making observations (qualitative: no numbers, quantitative: number & a unit)2) formulating hypotheses (possible explanation for an observation)3) performing experiments (carried out to test whether a hypothesis is valid)
What are the 2 fundamental concepts in chemistry?
1) matter is composed of various types of atoms2) one substance changes to another by reorganizing the way the atoms are attached to each other
Define theory
A set of assumptions put forth to explain the observed behavior of matter
Define model
Usually involve assumptions about the behavior of individual atoms or molecules
Theories are a set of __ __ that help focus our questions
Tested hypotheses
An __ is something that is witnessed and can be recorded; a __ is an interpretation, a possible explanation of why nature behaves in a particular way
ObservationTheory
Define natural law
Statement that expresses generally observed behavior
Define law of conservation of mass
Mass is neither created nor destroyed
A __ summarizes what happens, a __ (__) is an attempt to explain why it happens
LawTheory (model)
__ stated an __ is anything that cannot be broken down into simpler substances
BoyleElement
Who’s the father of modern chemistry?
Lavoisier
A measurement (__ observation) always consists of two parts: a __ & a __
QuantitativeNumberUnit
Physical quantity: massName of unit:Abbreviation:
Name of unit: kilogramAbbreviation: kg
Physical quantity: lengthName of unit:Abbreviation:
Name of unit: meterAbbreviation: m
Physical quantity: time Name of unit:Abbreviation:
Name of unit: secondAbbreviation: s
Physical quantity: temperature Name of unit:Abbreviation:
Name of unit: kelvinAbbreviation: K
Physical quantity: electric currentName of unit:Abbreviation:
Name of unit: ampere Abbreviation: A
Physical quantity: amount of substanceName of unit:Abbreviation:
Name of unit: moleAbbreviation: mol
Physical quantity: luminous intensity Name of unit:Abbreviation:
Name of unit: candelaAbbreviation: cd
1 liter = (1 __)^3 = (10 __)^3 = 1000 __^3 = 1000 __
dmcmcmmL
1 cm^3 = 1 __1 m^3 = 1000 __
mLL
Common types of lab equipment used to measure liquid volume (4)
Graduated cylinder, pipet, buret, volumetric flask
Volume measurements are read at the bottom of the liquid curve called the __. __ & __ are not the same
MeniscusMass Weight
Define mass
A measure of the resistance of an object to a change in its state of motion (the quantity of matter in an object)
Define weight. Weight varies with the strength of the __ __
The force exerted on an object by gravity. Gravitational field
Prefix: megaSymbol:Meaning:
Symbol: MMeaning: 10^6
Prefix: kiloSymbol:Meaning:
Symbol: kMeaning: 10^3
Prefix: hectoSymbol:Meaning:
Symbol: hMeaning: 10^2
Prefix: deka Symbol:Meaning:
Symbol: daMeaning: 10^1
Prefix: deciSymbol:Meaning:
Symbol: dMeaning: 10^-1
Prefix: centiSymbol:Meaning:
Symbol: cMeaning: 10^-2
Prefix: milliSymbol:Meaning:
Symbol: mMeaning: 10^-3
Prefix: microSymbol:Meaning:
Symbol: uMeaning: 10^-6
Prefix: nanoSymbol:Meaning:
Symbol: nMeaning: 10^-9
Define certain digits. Define uncertain digit
Remain the same no matter who’s measuring.Estimated #.
Report measurements by recording all the __ digits plus the first __ digit
CertainUncertain
A measurement always has some degree of __ which depends on the __ device
Uncertainty Measuring
Define uncertainty
Characteristic that any measurement involves estimates and cannot be exactly reproduced (uncertainty in the last number is assumed to be +/- 1 unless otherwise indicated)
Define significant figures
The certain digits and the first uncertain digit of a measurement
Two terms often used to describe the reliability of measurements are __ and __
PrecisionAccuracy
Define accuracy
The agreement of a particular value with the true value
Define precision
The degree of agreement among several measurements of the same quantity; the reproducibility of a measurement
Define random error (intermediate error)
An error that has an equal probability of being high or low (occurs in estimating the value of the last digit in a measurement)
Define systematic error (determinate error)
An error that always occurs in the same direction
In quantitative work, __ is often used as an indication of accuracy (assume the __ of precise measurements is accurate; only valid when there are no __ __)
PrecisionAverageSystematic errors
Rules for counting significant figures (5)
1) nonzero integers are always significant 2) zeros preceding all nonzero digits are not significant3) zeros between nonzero digits are always significant 4) all zeros after nonzero digits are significant only when there’s a decimal point5) exact numbers have an infinite # of sig figs and do not limit the # of sig figs in a calculation
Define exponential notation
Expresses a # as N • 10^M, a convenient method for representing a very large or very small number and for easily indicating the number of significant figures
For multiplication/division, the # of sig figs in the result is the same as the # in the __ __ measurement used in the calculation
Least precise
For addition or subtraction, the result has the same number of __ __ as the __ __ measurement used in the calculation
Decimal placesLeast precise
Rules for rounding (2)
1) in a series of calculations, carry the extra digits through to the final result, then round2) if the digit to be removed: a) is less than 5, the preceding digit remains the same, b) is equal to or greater than 5, the preceding digit is increased by 1
When rounding, use only the first number to the __ of the last sig fig
Right
Define the unit factor method (dimensional analysis)
An equivalence statement between units used for converting from one unit to another
Define unit factor
Converting an equivalence statement into a fraction
Converting from one unit to another (3)
1) use the equivalence statement that relates the two units 2) derive the appropriate unit factor by looking at the direction of the required change to cancel unwanted units3) multiply the quantity to be converted by the unit factor to give the quantity with the desired units
Three systems for measuring temperature
Celsius scaleKelvin scaleFahrenheit scale
The __ & __ scales both have the same size of the temperature unit (degree)
CelsiusKelvin
Temp kelvin = temp celsius _ 273.15Temp celsius = temp kelvin _ 273.15
+-
_F = _C & _F = _C(F - 32F) • (5C/9F) = __(C • (9F/5C)) + 32F = __
9F = 5C & -40F = -40CTemperature celsius Temperature Fahrenheit
Define density
Property of matter representing mass of substance per unit volume of the substance Density = mass / volume (g/cm^3)
Define matter
Anything occupying space and having mass; the material of the universe
Matter exists in what 3 states
Solid LiquidGas
Define states
The 3 different forms in which matter can exist (solid, liquid, gas)
Define solid
Rigid, has a fixed volume and fixed shape
Define liquid
Has a definite volume but no specific shape, it takes the shape of its container
Define gas
No fixed volume and no fixed shape, takes on the shape and volume of its container
Solids & liquids: __ compressibleGases: __ compressible, easy to decrease __
SlightlyHighly Volume
Define mixture
Has variable composition of pure substances, is homogeneous or heterogeneous
Define heterogenous
Having visibly distinguishable parts, can usually be separated into 2 or more homogeneous mixtures or pure substances
Define homogeneous
Having visibly indistinguishable parts
Define solution
A homogeneous mixture
Define pure substance
Substance with constant composition
Define physical change
Change in the form of a substance, not in its chemical composition; chemical bonds are not broken in a physical change (can separate mixtures into pure compounds)
__ can be separated by methods involving only physical changes
Mixtures
Define distillation
A method for separating the components of a liquid mixture that depends on differences in the ease of vaporization of the components
Define volatility
How readily substances become gases; the ease with which a substance can be changed to its vapor
Define simple distillation
Mixture is heated, most volatile component vaporizes at the lowest temperature, and the vapor passes through a cooled tube (condenser) where it condenses back into its liquid state
When a mixture contains several volatile components, one-step distillation doesn’t give a __ __ in the receiving flask
Pure substance
Define filtration
A method for separating the components of a mixture containing a solid & a liquid (mixture poured onto mesh filter paper which passes the liquid and leaves the solid behind
Define chromatography
The general name for a series of methods for separating mixtures by employing a system with two phases (states) of matter: a mobile phase & stationary phase
Stationary phase: __Mobile phase: either __ or __
SolidLiquid or gas
Component with a high affinity: mobile phase- __ __, stationary phase- __ __
Moves quicklyMoves slowly
Define paper chromatography
Uses a strip of porous paper for the stationary phase, drop of mixture to be separated is placed on the paper, paper dipped into a liquid (mobile phase) that travels up the paper; often used by biochemists
Pure substances contain __ (combinations of __) or __ __
CompoundsElementsFree elements
Define compound
A substance with constant composition that can be broken down into elements by chemical processes
Define chemical change
The change of substance into other substances with different properties and different composition through a reorganization of the atoms; a chemical reaction
Define element
Substance that cannot be decomposed into simpler substances by chemical or physical means
