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INTRO AND BACKGROUND:Measurement, Uncertainty, Matter,
Periodicity, and Nomenclature
Accuracy vs. PrecisionACCURACY
Closeness to the true value
PRECISIONHow close a series of measurements are to each other*Tools with MORE numbers after the decimal
= MORE precise
WHEN MAKING MEASUREMENTS, IT�S GOOD TO HAVE BOTH!!
Accuracy vs. Precision % ErrorCompare a measurement to its accepted value
% ERROR
EXPERIMENTAL VALUE
ACCEPTED VALUE
ACCEPTED VALUE
100
• EXAMPLE:Sally found the mass of a 34.0 g sample to be 32.7 g.
What is the % error in her measurements?
3.82%
Significant Figures
�SIG FIGS�
All the numbers that are certain in a measurement, including one that is uncertain
• RULES:1) All non zero digits are significant2) Zeros between other sig figs count
Ex: 10023) Zeros at the end before an implied decimal point
don�t count (if it�s there then they do)Ex: 12400 / 400.
4) When a number is smaller than one, zeros before the first S.F. don�t countEx: 0.045
5) Zeros after a decimal do count (once you have a S.F.)Ex: 45.8300
Rounding with Sig Figs• If digit to the right is LESS than 5… LEAVE IT BE!!
(Ex: 56.43 with 3 Sig Figs would be 56.4)
• If digit to the right is GREATER than 5… ROUND UP!!(Ex: 67.39 with 3 Sig Figs would be 67.4)
• If digit to the right EQUALS 5… GO FOR EVEN #s!!(Ex: 94.65 with 3 Sig Figs would be 94.6, while 94.75 with 3 Sig Figs would be 94.8)
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Math with Sig Figs•Multiplication and Division:
Ex: 3.052 X 2.10 X 0.75 = 4.8069
CORRECT SIG FIGS = 4.8
• Addition and Subtraction:
Ex: 3.45645 mL – 2.43 mL = 1.02645 mL
CORRECT SIG FIGS = 1.03 mL
Count SIG FIGS in each separate term and use the LEAST amount in the answer!
Count DECIMAL PLACES in each separate term and use the LEAST amount in the answer!
Sig Fig Practice• How many sig figs are in these numbers?
1) 91,600
2) 0.003005
• Calculate and round using the appropriate rule:3) 0.04216 + 0.0004134 =
4) (5.610) x (34.908) x (2.30) =
Prefixes
Positive exponents are LARGER than the base unit, while negative are SMALLER!!
M (mega) = 106
k (kilo) = 103
D (deka) = 101
d (deci) = 10-1
c (centi) = 10-2
m (milli) = 10-3
µ (micro) = 10-6
n (nano) = 10-9
Ex: 1 km = 1,000 m(KILO is
LARGER!)
Ex: 1,000 mm = 1 m
(MILLI is SMALLER!)
Temperature Conversions• Equations to know:
-FAHRENHEIT TO CELSIUSC = .56 X (F – 32)
-CELSIUS TO FAHRENHEITF = ( 1.8 X C ) + 32
-CELSIUS TO KELVINK = C + 273
• EXAMPLE:
What is -14 °C expressed in Kelvin?
259 K
Know the reverse as
well!
IGNORE!
IGNORE!
Conversion Factors• Amounts can be expressed in different EQUAL ways
SOME COMMON CONVERSIONS:
1 in = 2.54 cm1 ft = 12 in1 yd = 3 ft1 mi = 5280 ft1 m = 10 dm1 m = 100 cm
1 m = 1000 mm1000 m = 1 km1 g = 10 dg1 g = 100 cg1 g = 1000 mg1000 g = 1 kg
1 mL = 1 cm3
1000 mL = 1 L1 min = 60 s1 hr = 60 min1 day = 24 hr365 days = 1 yr
Dimensional Analysis• EXAMPLE:
What is 5 km expressed in meters?
5 km X 1000 m1 km
= 5,000 m
• In order to cancel a unit, one must be on the �top� and the other must be on the �bottom� (immediately write the top unit on the bottom for the conversion factor)!!
REMEMBER… THE UNITS ARE YOUR FRIENDS!!
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Dimensional Analysis• MORE EXAMPLES:
a) 3.48 g to kg
b) 12.3 L to mL
c) 66 mm to km
d) 1.130 days to s
0.00348 kg
12,300 mL
0.000066 km
97,630 s
DensityRelationship of mass to volume
D = Mass / Volume• Units are g / mL or g / cm3
• INTENSIVE PROPERTY: amount of the substance does not affect it
• If density is given, mass or volume could be determined…
M = D x V V = M / D
Practice
A piece of wood has a mass of 11.2 g and a volume of 23 mL. What is the density?
Mercury metal is poured into a graduated cylinder that holds 22.5 mL. The mercury used to fill the
cylinder weighs 0.3060 kg. Calculate the density (in g/cm3) of mercury.
Practice
A piece of wood has a density of 0.82 g/mL and a volume of 0.031 L. What is the mass of the wood in mg?
Aluminum has a density of 2.70 g/cm3. What is the mass (in kg) of a cube with a side of 6.78 cm?
How Does Something Float?• Lower density items FLOAT on higher density items… ice is less dense than water!
•Most wood is less dense than water
• Helium is less dense than air
• A ship is less dense than water
MatterAnything that has mass and takes
up space
THREE STATES OF MATTER
• SOLID: definite shape, definite volume, high density, not easily compressed, slow moving particles
• LIQUID: indefinite shape, flows but has a definite volume, not easily compressed
• GAS: indefinite shape, indefinite volume (takes the shape of the container), low density, easily compressed, fast moving particles (VAPOR = gaseous state that is liquid or solid)
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Describing MatterINTENSIVE PROPERTY
EXTENSIVE PROPERTY
Depends on the type of matter, NOT the amount
Depends on the amount of matter present
EX: Hardness, density, color, melting point
EX: Mass, volume, weight
Types of Properties• PHYSICAL PROPERTY: quality observed or measured WITHOUT changing the substance�s composition
EX: state, color, melting point, density
• CHEMICAL PROPERTY: observed only if the substance undergoes a chemical change
EX: ability to oxidize (rust), flammability, ability to ferment
Types of Changes
• PHYSICAL CHANGE: properties of the material may change, but NOT the composition (REVERSIBLE)
EX: cutting, melting, boiling, freezing, crushing
• CHEMICAL CHANGE: the composition of the matter always changes (IRREVERSIBLE)
EX: cooking food, photosynthesis, rusting
MixturePHYSICAL blend of two or more components
TWO TYPES:• HOMOGENEOUS è uniform composition throughout
• HETEROGENEOUS è NOT uniform in composition
SolutionHomogeneous mixture in which one substance
is dissolved in another• SOLUTE: substance that is dissolved• SOLVENT: substance doing the dissolving
Solution Solute Solvent
Lemonade
Soda pop
Ocean water
• INSOLUBLE: does NOT dissolve• SOLUBLE: does dissolve
SUGAR
SUGAR
SALT
WATER
WATER
WATER
Separating Mixtures• Differences in PHYSICAL properties can be used to separate mixtures
1) DECANT: pour off one layer leaving behind another layer of a mixture (density)
2) FILTRATION: separates a solid from the liquid
3) MAGNET: removes substances that are magnetized (ex: iron filings)
4) CHROMATOGRAPHY: separates colors
5) DISTILLATION: uses a difference in boiling points of two substances to separate them
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Distillation Apparatus Pure SubstanceComposition does NOT vary
TWO TYPES:• ELEMENT è simplest form of matter that has a unique set of properties
(Ex: hydrogen, oxygen, gold, lead)
• COMPOUND è contains two or more elements CHEMICALLY combined in a fixed proportion
(Ex: water, carbon dioxide, sugars)
Reaction LawsLAW OF CONSERVATION OF ENERGY
Energy can neither be created nor destroyed… only changed from one form to another!
LAW OF CONSERVATION OF MASSMass can neither be created nor destroyed… Total mass in the universe is constant!
Periodic Law
•MOSELEY (1913) developed the Modern Periodic Table
• Arranged elements in order of increasing atomic number
Properties of elements repeat when placed in order of INCREASING atomic number
Reading the Table• PERIOD: Row on the Periodic Table / Energy level• GROUP: Column (families) with similar physical and chemical properties
Three classes of elements on the Periodic Table…
MetalsFound on the left hand side and middle
of the table• About 80% of elements are in this class• High luster (shiny)• Good conductors of heat and electricity• Typically solids at room temperature (except Hg)• DUCTILE: can be drawn into wires•MALLEABLE: hammered into thin sheets
• High density and melting point
• Form cations (+)
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Metals NonmetalsFound on the right hand side of the
table
• No luster
• Poor conductors of heat and electricity•Most (not all) are gases at room temp
• Low density and melting point
• Not malleable or ductile• Brittle
• Tend to form anions (-)
Nonmetals MetalloidsFound along the �staircase� on
the table
• Have properties of both metals and nonmetals
• Ex: B, Si, Ge, As, Sb, Te, Po, and At• Ion formation depends on their group
Arsenic Poisoning (from H2O)
Metalloids Periodic Table Groups
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Why Are Families Similar?
Each family has the same number of VALENCE ELECTRONS (outermost
electrons of an atom) which determines an element’s properties… All want EIGHT!!
IonsCharged (+ or -) atoms
• Atoms in their elemental state are NEUTRAL (protons and electrons are EQUAL)
• Atoms can gain or lose electrons giving them a charge
• Ions have DIFFERENT number of protons and electrons
CationsPositively (+) charged ions
• Atoms that LOSEelectrons become cations (loss of negatively charged particles)
• Formed from Metals
• Number of electrons lost determines the charge (1+, 2+, etc.)
BOINK!
BOINK!
MAGNESIUM
Mg 2+
AnionsNegatively (-) charged ions
• Atoms that GAINelectrons become anions (more negatively charged particles)
• Formed from Nonmetals
• Number of electrons gained determines the charge (1-, 2-, etc.)
CHLORINE
Cl 1-
What Determines the Charge?
LOCATION on the Periodic Table and VALENCE ELECTRONS!!
1+2+ 3+ 3- 2- 1-
What Determines the Charge?
Atoms want EIGHT electrons in their outer or highest energy level to be stable… They want to be like a NOBLE GAS! So they GAIN
or LOSE electrons to accomplish this... Whichever is EASIER!!!!
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Factors Influencing Trends1) Electron Energy Level: distance
from the nucleus
2) Effective Nuclear Charge (Zeff): # of protons influences the pull on the electrons (how strong the nucleus is)
3) Shielding Effect: valence electrons are �shielded� from the pull / charge of the nucleus by all the electrons in between
+
Atomic RadiusHalf the distance between the nuclei of two atoms
of the same element (aka ATOMIC SIZE)
• Trend: INCREASES down a column and DECREASESgoing across a row
Atomic Radius
WHY DOES IT FOLLOW THIS TREND?
As you go down a column, the number of e- and energy levels increase… so the radius INCREASES!
HLi
Na
K
Rb
• Group:
Half the distance between the nuclei of two atoms of the same element (aka ATOMIC SIZE)
Atomic Radius
WHY DOES IT FOLLOW THIS TREND?
As you go across a row, all e- are in the same energy level and the nuclear charge is larger, causing the outer e- to be held tighter… so it DECREASES!
• Row:
Na Mg Al Si P S Cl Ar
Half the distance between the nuclei of two atoms of the same element (aka ATOMIC SIZE)
Atomic RadiusHalf the distance between the nuclei of two atoms
of the same element (aka ATOMIC SIZE)
Ionic RadiusHalf the distance between two ions
• Trend: INCREASES down a column and DECREASESgoing across a row for cations and anions, but cations are SMALLER and anions are LARGER
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WHY DOES IT FOLLOW THIS TREND?
As you go down a column, the number of e- and energy levels increase… so the radius INCREASES!
• Group:
Ionic RadiusHalf the distance between two ions
WHY DOES IT FOLLOW THIS TREND?
Cations are SMALLER because as e- are lost nuclear charge increases and holds tighter, while anions are LARGERbecause as e- are added nuclear charge decreases and does not hold as tight… but each type still DECREASES as go across!
• Row:
Ionic RadiusHalf the distance between two ions
Ionization EnergyAmount of energy required to remove a
valence electron from an atom
• Trend: DECREASES down a column and INCREASESgoing across a row
Ionization EnergyAmount of energy required to remove a
valence electron from an atom
WHY DOES IT FOLLOW THIS TREND?
As you go down a column, more energy levels are added and the valence e- are more �shielded� from the pull of the nucleus, making it easier to remove an e-… so it DECREASES!
• Group:
Ionization EnergyAmount of energy required to remove a
valence electron from an atom
WHY DOES IT FOLLOW THIS TREND?
As you go across a row, the nuclear charge gets greater (holds e-tighter) and the orbital gets closer to being full which adds stability, making it harder to remove an e-… so it INCREASES!
• Row:
Ionization EnergyAmount of energy required to remove a
valence electron from an atom
• Watch for EXCEPTIONSlike Be / B, N / O, etc.... WHY do they occur?• To remove a second e-, even MORE energy is required (gets harder to steal) so I.E. INCREASESwith each electron removed!• Number of valence e- can also be seen… look for jumps in energy (Ex: Be)
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Ionization EnergyAmount of energy required to remove a
valence electron from an atom
ElectronegativityAbility of an atom to attract electrons
when the atom is in a compound
• Trend: DECREASES down a column and INCREASESgoing across a row
ElectronegativityAbility of an atom to attract electrons
when the atom is in a compound
WHY DOES IT FOLLOW THIS TREND?
As you go down a column, more energy levels are added, making the valence e- farther from the nucleus and not held as �tightly�due to shielding… so it DECREASES!
• Group:
ElectronegativityAbility of an atom to attract electrons
when the atom is in a compound
WHY DOES IT FOLLOW THIS TREND?• Row:
As you go across a row, the nuclear charge increases, making it easier to attract e- to the atom… so it INCREASES!
Electron AffinityAmount of energy released when an
electron is added
• Trend: DECREASES down a column and INCREASESgoing across a row
WHY DOES IT FOLLOW THIS TREND?Think in terms of electronegativity… the stronger the attraction to an e-, the more energy is released!
*MORE negative number = MORE energy released!
Metallic / Reactivity
• As you go down a group of METALS, the metallic character and reactivity of the metals INCREASE
• As you go down the HALOGENS, the reactivity DECREASES! Therefore, the most reactive element in the halogen family is Fluorine!!
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Ionic BondTRANSFER of electrons between atoms forming opposite charges which attract to each other
• Each atom achieves a noble gas configuration (full valence shell)
• Usually between a METAL and a NONMETAL
• Formula Unit: lowest whole-number ratio of ions in an ionic compound (ex: NaCl or MgCl2)
Naming Ionic Compounds• To name an IONIC compound, ask yourself this question first…
Is the METAL in the compound MULTI-CHARGED? (in the d-block including Pb
and Sn, but NOT Zn or Ag)
Naming Ionic Compounds• EXCEPTIONS:
-All transition metals (d-block) are multi-charged except Ag is always Ag1+ and Zn is always Zn2+ so no Roman numerals are needed
-Pb and Sn behave like transition metals
Naming Ionic Compounds• If the answer is NO…
1) Name the cation (metal) first… remember it keeps its name
2)Then name the anion (nonmetal)… ending in -ide
• EXAMPLE:Name the following compound: AlBr3
Aluminum bromide
Naming Ionic Compounds• If the answer is YES…
1) Criss-cross the SUBSCRIPTS and make them the charges (metals = �+� / nonmetals = �-�)
2)Check the charge on the anion (-) and see if it is correct… if it is NOT, multiply the �-� charge by a # to get the correct charge and then multiply the �+� charge by the same #
3)Write the name of the metal with its charge in parentheses as a Roman numeral [I, II, III, IV] followed by the nonmetal with an �ide� ending
Naming Ionic Compounds• EXAMPLES:
Name the following compound: Fe2O3
IRON IS A MULTI-CHARGE METAL!!
Fe2O3 Iron (III) oxide= Fe3+ O2-
Name the following compound: ZnCl2
Make sure charge on anion is correct!!
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Naming Ionic Compounds• If the compound has a POLYATOMIC ION:
1) Follow all previous rules, but the polyatomic ions get to keep their name
• EXAMPLES:Name the following compound: KNO3
Name the following compound: NH4Cl
Naming Ionic Compounds• If the compound is a HYDRATE (contains water)…
1) Follow all previous rules
2)Attach the correct PREFIX to the word �hydrate� to indicate the amount of water molecules present… put this right after the name
PREFIX NUMBER PREFIX NUMBERMono 1 Hexa 6
Di 2 Hepta 7Tri 3 Octa 8
Tetra 4 Nona 9Penta 5 Deca 10
Naming Ionic Compounds
• EXAMPLES:Name the following compound: CuSO4 • 5H2O
Name the following compound: Pb(ClO4)2 • 3H2O
Ionic Compound Formulas• Rules for writing formulas…
1) Write the SYMBOL of each element or ion from the name (cation is always written first followed by the anion)
2)Determine the CHARGE on each…
-Multi-Charged: it�s in the ( )-Polyatomic: keeps its charge-Otherwise: get from the table
3)Criss-cross the charges and make them SUBSCRIPTS… simplify (reduce), if possible
Ionic Compound Formulas
• EXAMPLE:Write the formula for calcium chloride.
Ca 2+ Cl -
CaCl22+ = 2-
Ionic Compound Formulas• If POLYATOMIC IONS are present…
1) Follow all previous rules
2)Treat polyatomic ions as a whole… put in parentheses when subscripts are used
Fe(OH)3
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Ionic Compound Formulas• If the compound is a HYDRATE (contains water)…
1) Follow all previous rules
2)Use the PREFIX in front of �hydrate� to indicate the number of water molecules... Write this after the name by adding �• #H2O�
• EXAMPLE:Write the formula for iron (III) chloride
hexahydrate.
Covalent BondSHARING of electrons between atoms to
satisfy the octet rule
• Involves two NONMETALS
• Known as covalent or molecular compounds
•MOLECULE: group of atoms joined by a covalent bond
• DIATOMIC MOLECULES: elements that cannot exist as single atoms
Ex: H2, N2, O2, F2, Cl2, Br2, and I2
HONClBrIF (Honkle-Briff)
Naming Covalent Compounds• Naming a covalent / molecular compound:
1) Write the name of the first element
2)Change the ending of the second element to –ide
3)Add correct PREFIXES to each to indicate the number of atoms (no mono on FIRST element)
PREFIX NUMBER PREFIX NUMBERMono 1 Hexa 6
Di 2 Hepta 7Tri 3 Octa 8
Tetra 4 Nona 9Penta 5 Deca 10
Covalent Compound Formulas• Rules for writing covalent / molecular formulas:
1) Write each element symbol from the name
2)Use PREFIX in the name to determine the subscript for each element… DO NOT SIMPLIFY!!!
• EXAMPLE:Write the formula for dinitrogen pentoxide.
HydrocarbonsCompounds made of carbon and hydrogen
• Organic compounds… Three groups we will look at: Alkanes, Alkenes, and Alkynes
• Named with PREFIXES based on the number of carbon atoms present:
PREFIX # OF C PREFIX # OF CMeth 1 Hex 6Eth 2 Hept 7
Prop 3 Oct 8But 4 Non 9Pent 5 Dec 10
Alkanes• Have the generic formula: CnH2n+2
• Contains all single bonds
• Naming: Use the correct prefix with –ane ending• Formula: Prefix determines how many carbons… Do the math to determine the number of hydrogens
• EXAMPLES:Name the following compound: C3H8
Write the formula for butane.
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Alkenes• Have the generic formula: CnH2n
• Contains one double bond
• Naming: Use the correct prefix with –ene ending• Formula: Prefix determines how many carbons… Do the math to determine the number of hydrogens
• EXAMPLES:Name the following compound: C6H12
Write the formula for decene.
Alkynes• Have the generic formula: CnH2n-2
• Contains one triple bond
• Naming: Use the correct prefix with –yne ending• Formula: Prefix determines how many carbons… Do the math to determine the number of hydrogens
• EXAMPLES:Name the following compound: C5H8
Write the formula for octyne.
Naming Acids• Rules for naming acids:
1) Hydrogen atom connected to anion (-) that ends in –ide then it is named…
• hydro- root of the element- ic acid
• EXAMPLES:
HCl
H2S
Naming Acids• Rules for naming acids:
2) Hydrogen atom connected to a polyatomic ion ending with –ite then it is named…
• (root of the polyatomic ion)- ous acid
• EXAMPLES:
HClO2
HNO2
Naming Acids• Rules for naming acids:
3) Hydrogen atom connected to a polyatomic ion ending with –ate then it is named…
• (root of the polyatomic ion)- ic acid
• EXAMPLES:
HClO3
H2SO4
Acid Formulas• Rules for writing formulas of acids:
1) Hydrogen (H+) usually written first
2)Name indicates the anion (-) in the formula
3) Write the charges for each symbol and criss-cross to get subscripts
• EXAMPLE:
Sulfurous acid