chapter 3: elements, compounds, and the periodic table
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Chapter 3: Elements, Compounds, and the Periodic Table. Chemistry: The Molecular Nature of Matter, 6E Jespersen/Brady/Hyslop. Discovery of Subatomic Particles. Late 1800s & early 1900s Cathode ray tube experiments showed that atoms are made up of subatomic particles - PowerPoint PPT PresentationTRANSCRIPT
Chapter 3: Elements, Compounds,and the Periodic Table
Chemistry: The Molecular Nature of Matter, 6E
Jespersen/Brady/Hyslop
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Discovery of Subatomic Particles Late 1800s & early 1900s
Cathode ray tube experiments showed that atoms are made up of subatomic particles
Discovered negatively charged particles moving from Cathode – negative electrode to Anode – positive electrode
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Discovery of ElectronJJ Thomson (1897) Modified cathode ray tube Made quantitative
measurements on cathode rays
Discovered negatively charged particles Electrons (e)
Determined charge to mass ratio (e/m) of these particles e/m = 1.76 x 108 coulombs/gram
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Millikan Oil Drop Experiment Determining charge on Electron Calculated charge on electron
e = 1.60 x 1019 C
Combined with Thomson’s experiment to get mass of electron m = 9.09 x 1028 g
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Discovery of Atomic NucleusRutherford’s Alpha Scattering Experiment
Most alpha () rays passed right through gold A few were deflected off at an angle 1 in 8000 bounced back towards alpha ray
source Gave us current model of nuclear atom
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Discovery Of Proton Discovered in 1918 in Ernest Rutherford’s
lab Detected using Mass Spectrometer
Hydrogen had mass 1800x mass of electron Masses of other gases whole number multiples
of mass of hydrogen
Proton Smallest
positively charged particle
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Rutherford’s Nuclear Atom Demonstrated that nucleus:
has almost all of mass in atom has all of positive charge is located in very small volume at center of
atom
Very tiny, extremely dense core of atom Where protons (p+) &
neutrons (1n) are located
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Atomic Structure Electrons (e)
Very low mass Occupy most of atom’s space
Balance of attractive & repulsive forces controls atom size
Attraction between protons (p+) & electrons (e) holds electrons around nucleus
Repulsion between electrons helps them spread out over volume of atom
In neutral atom Number of es must equal number of p+s Diameter of atom ~10,000 × diameter of
nucleus8
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Discovery of Neutron (1n) First postulated by Rutherford & coworkers
Estimated number of positive charges on nucleus based on experimental data
Nuclear mass based on this number of protons always far short of actual mass About ½ actual mass
Therefore, must be another type of particle Has mass about same as proton Electrically neutral
Discovered in 1932 by Chadwick Caused free neutron to be created
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Properties of Subatomic Particles
Particle Mass (g)Electrical Charge
Symbol
Electron
9.10939102
8 1
Proton1.67264102
4 +1
Neutron1.67495102
4 0
e01
p1111 ,H
n10
3 Kinds of subatomic particles of principal interest to Chemists
Nucleus (protons + neutrons)
Electrons
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Atomic NotationAtomic number (Z) Number of protons that atom has in nucleus
Unique to each type of element Element is substance whose atoms all contain
identical number of protons
Z = # protonsIsotopes Atoms of same element with different
masses Same number of protons ( ) Different number of neutrons ( )
11
p11
n01
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Atomic NotationIsotope Mass number (A)
A = (# protons) + (# neutrons) A = Z + N For charge neutrality, number of electrons &
protons must be equal
Atomic Symbols Summarize information about subatomic
particles Every isotope defined by 2 numbers Z & A Symbolized by
Ex. What is the atomic symbol for helium? He has 2 e–, 2 n & 2 p+ Z = 2, A = 4
12
XAZ
He42
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Isotopes Most elements are mixtures of 2 or more
stable isotopes Each isotope has slightly different mass Chemically, isotopes have virtually identical
chemical properties Relative proportions of different isotopes are
essentially constant Isotopes distinguished by mass number (A):
Ex. 3 isotopes of hydrogen (H) 4 isotopes of iron (Fe)
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Example:What is the isotopic symbol for Uranium-
235? Number of protons (p+) = 92
= number of electrons in neutral atom Number of neutrons (1n) = 143 Atomic number (Z) = 92 Mass number (A) = 92 + 143 = 235 Chemical symbol = U
Summary for uranium-235:
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U23592
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Learning Check:
Fill in the blanks:symbol neutrons protons electrons60Co 81Br
36 29 29
33 27 27
46 35 35
Cu6529
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!
An atom of has ___ protons, ___ neutrons, and ___ electrons.A. 82, 206, 124
B. 124, 206, 124
C. 124, 124, 124
D. 82, 124, 82
E. 82, 124, 124
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20682Pb
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Carbon-12 Atomic Mass Scale Need uniform mass scale for atoms
Atomic mass units (symbol u) Based on carbon: 1 atom of carbon-12 = 12 u (exactly) 1 u = 1/12 mass 1 atom of carbon-12
(exactly)
Why was 12C selected? Common Most abundant isotope of carbon All atomic masses of all other elements ~ whole
numbers Lightest element, H, has mass ~1 u
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Calculating Atomic Mass Generally, elements are mixtures of isotopes
Ex. HydrogenIsotope Mass %Abundance
1H 1.007825 u 99.985
2H 2.0140 u 0.015
How do we define Atomic Mass? Average of masses of all stable isotopes of given
element
How do we calculate Average Atomic Mass? Weighted average. Use Isotopic Abundances & isotopic masses
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Learning CheckNaturally occurring magnesium is a mixture of 3 isotopes; 78.99% of the atoms are 24Mg (atomic mass, 23.9850 u), 10.00% of 25Mg (atomic mass, 24.9858 u), and 11.01% of 26Mg (atomic mass, 25.9826 u). From these data calculate the average atomic mass of magnesium.
0.7899 * 23.9850 u = 18.946 u 24Mg
Total mass of average atom = 24.3053 u rounds up to 24.31 u
0.1000 * 24.9858 u = 2.4986 u 25Mg0.1101 * 25.9826 u = 2.8607 u 26Mg
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!A naturally occurring element consists of two isotopes. The data on the isotopes:
isotope #1 68.5257 u 60.226%
isotope #2 70.9429 u 39.774%
Calculate the average atomic mass of this element.
A.70.943 u
B.69.487 u
C.69.526 u
D.69.981 u
E.69.734 u20
0.60226 * 68.5257 u = 41.270 u0.39774 * 70.9429 u = 28.217 u
69.487 u
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
21
Periodic Table Summarizes periodic properties of elements
Early Versions of Periodic Tables Arranged by increasing atomic mass Mendeleev (Russian) & Meyer (German) in
1869 Noted repeating (periodic) properties
Modern Periodic Table Arranged by increasing atomic number (Z): Rows called periods Columns called groups or families
Identified by numbers 1 – 18 standard international 1A – 8A longer columns & 1B – 8B shorter columns
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Modern Periodic Tablewith group labels and chemical families identified
Note: Placement of elements 58 – 71 and 90 – 103 saves space
Actinides
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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A groups—Longer columns Alkali Metals
1A = first group Very reactive All Metals except for H Tend to form +1 ions React with oxygen
Form compounds that dissolve in water Yield strongly caustic or alkaline solution
(M2O)
Representative/Main Group Elements
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Representative/Main Group Elements
A groups—Longer columns Alkaline Earth Metals
2A = second group Reactive Tend to form +2 ions Oxygen compounds are strongly alkaline
(MO) Many are not water soluble Accumulate in ground
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Representative/Main Group Elements
A groups—Longer columns Halogens
7A = next to last group on right Reactive Form diatomic molecules in elemental
state 2 gases 1 liquid 2 solids
Form –1 ions with alkali metals—salts25
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Representative/Main Group Elements
A groups—Longer columns Noble Gases
8A = last group on right Inert—very unreactive Only heavier elements of group react & then
very limited Don’t form charged ions Monatomic gases
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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B groups—shorter columns All are metals In center of table Begin in fourth row Tend to form ions with several different
charges
Ex. Fe2+ and Fe3+ Cu+ and Cu2+
Mn2+, Mn3+, Mn4+, Mn5+, Mn6+, Mn7+
Note: Last 3 columns all have 8B designation
Transition Elements
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Lanthanide elements Elements 58 – 71
Actinide elements Elements 90 – 103 At bottom of periodic table Tend to form +2 and +3 ions. All Actinides are radioactive
Inner Transition Elements
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Metals, Nonmetals, or Metalloids Elements break down into 3 broad categories
Organized by regions of periodic table
Metals Left-hand side Sodium, lead, iron, gold
Nonmetals Upper right hand corner Oxygen, nitrogen, chlorine
Metalloids Diagonal line between metals & nonmetals Boron to astatine
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Metals, Nonmetals, or Metalloids
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Metals Most elements in periodic tableProperties Metallic luster
Shine or reflect light Malleable
Can be hammered or rolled into thin sheets
Ductile Can be drawn into wire
Hardness Some hard – iron & chromium Some soft – sodium, lead, copper
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Properties of Metals Conduct heat & electricity Solids at Room Temperature
Melting points (mp) > 25 °C Hg only liquid metal (mp = –39 °C) Tungsten (W) (mp = 3400 °C)
Highest known for metal
Chemical reactivity Varies greatly
Au, Pt very unreactive Na, K very reactive
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Nonmetals 17 elements
Upper right hand corner of periodic table Exist mostly as compounds rather than as
pure elements Many are Gases
Monatomic (Noble) He, Ne, Ar, Kr, Xe, Rn Diatomic H2, O2, N2, F2, Cl2
Some are Solids: I2, Se8, S8, P4, C
3 forms of Carbon (graphite, coal, diamond)
One is liquid: Br2
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Properties of Nonmetals Brittle
Pulverize when struck Insulators
Non-conductors of electricity and heat
Chemical reactivity Some inert
Noble gases Some reactive
F2, O2, H2
React with metals to form ionic compounds
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Metalloids 8 Elements
Located on diagonal line between metals & nonmetals
B, Si, Ge, As, Sb, Te, Po, At
Properties Between metals & nonmetals
Metallic shine Brittle like nonmetal
Semiconductors Conduct electricity But not as well as metals Silicon (Si) & germanium (Ge)
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Your Turn!
Which of the following statements is correct?
A.Cu is a representative transition elementB.Na is an alkaline earth metalC.Al is a semimetal in group IIIAD.F is a representative halogenE.None of these are correct
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!All of the following are characteristics of metals except:
A.Malleable
B.Ductile
C.Lustrous
D.Good conductors of heat
E.Tend to gain electrons in chemical reactions
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Ions & Ionic CompoundsIons
Transfer of 1 or more electrons from 1 atom to another
Form electrically charged particles
Ionic compound Compound composed of ions Formed from metal & nonmetal Infinite array of alternating Na+ & Cl ions
Formula unit Smallest neutral unit of ionic compound Smallest whole-number ratio of ions
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Formation of Ionic CompoundsMetal + Non-metal ionic
compound 2Na(s) + Cl2(g) 2NaCl(s)
Na+ + ClNa + Cl NaCl(s)
e
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Ionic CompoundsCations
Positively charged ions Formed from metals Atoms lose electrons
Ex. Na has 11 e– & 11 p+
Anions Negatively charged ions Formed from non-metals Atoms gain electrons
Ex. Cl has 17 e– & 17 p+
Na+ has 10 e– & 11 p+
Cl– has 16 e– & 17 p+
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Experimental Evidence for Ions
Electrical conductivity requires charge movement
Ionic compounds: Do not conduct electricity in solid state Do conduct electricity in liquid & aqueous states
where ions are free to move
Molecular compounds: Do not conduct electricity in any state Molecules are comprised of uncharged particles
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Ions of Representative Elements
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Can use periodic table to predict ion charges
When we use North American numbering of groups: Cation positive charge = group #
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Ions of Representative Elements
N O F Ne
Noble gases are especially stable
Nonmetals Negative () charge on anion = # spaces
you have to move to right to get to noble gas
Expected charge on O is Move 2 spaces to right O2–
What is expected charge on N? Move 3 spaces to right N3 –
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Rules For Writing Ionic Formulas1. Cation given first in formula
2. Subscripts in formula must produce electrically neutral formula unit
3. Subscripts must be smallest whole numbers possible
Divide by 2 if all subscripts are even May have to repeat several times
4. Charges on ions not included in finished formula unit of substance
If no subscript, then 1 implied
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Determining Ionic FormulasEx. Formula of ionic compound formed
when magnesium reacts with oxygen Mg is group 2A
Forms +2 ion or Mg2+ O is group 6A
Forms –2 ion or O2–
To get electrically neutral particle need 1:1 ratio of Mg2+ & O2–
Formula: MgO
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Determining Ionic Formulas
“Criss-cross” rule Make magnitude of charge on one ion
into subscript for other When doing this, make sure that
subscripts are reduced to lowest whole number.
Ex. What is the formula of ionic compound formed between aluminum & oxygen ions? Al2O3Al3+ O2–
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!Which of the following is the correct formula for the formula unit composed of potassium and oxygen ions?
A.KO
B.KO2
C.K2O
D.P2O3
E.K2O2
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!Which of the following is the correct formula for the formula unit composed of Fe3+ and sulfide ions?
A.FeS
B.Fe3S2
C.FeS3
D.Fe2S3
E.Fe4S6
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Cations of Transition MetalsTransition metals
Center (shorter) region of periodic table Much less reactive than group 1A & 2A Still transfer electrons to nonmetals to form ionic compounds # of electrons transferred less clear Form more than 1 positive ion Can form more than 1
compound with same non-metal
Ex. Fe + Cl
FeCl2 & FeCl3
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Cations of Post-transition MetalsPost-transition metals
9 metals Ga, In, Sn, Tl, Pb, Bi, Uut, Uuq, Uub After transition metals & before metalloids 2 very important ones – tin (Sn) & lead (Pb)
Both have 2 possible oxidation states Both form 2 compounds with same nonmetal
Ex. Ionic compounds of tin & oxygen are SnO & SnO2
Bismuth Only has +3 charge Bi3+
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Ions of Some Transition Metals & Post-transition Metals
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Compounds with Polyatomic IonsBinary compounds
Compounds formed from 2 different elements
Polyatomic ions Ions composed of 2 or more atoms linked by
molecular bonds If ions are negative, they have too many
electrons If ions are positive, they have too few electrons
Formulas for ionic compounds containing polyatomic ions Follow same rules as ionic compounds Polyatomic ions are expressed in parentheses
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Table 3.4 Polyatomic Ions
(Alternate Name in parentheses)
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Learning CheckEx. What is the formula of the ionic
compound formed between ammonium and phosphate ions? Ammonium = NH4
+
Phosphate = PO43–
Ex. Between strontium ion and nitrate ion? Strontium = Sr2+ Nitrate = NO3
2–
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(NH4)+ (PO4)3–
(NH4)3PO4
Sr2+ (NO3)– Sr(NO3)2
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Nomenclature (Naming) IUPAC system to standardize name of
chemical compounds One system so that anyone can
reconstruct formula from name We will look at naming Ionic Compounds of
Representative metals Transition metals Monatomic ions Polyatomic ions Hydrates
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Cations: Metal that forms only 1 positive ion
Cation name = English name for metal Na+ sodium Ca2+ calcium
Metal that forms more than 1 positive ion Use Stock System
Cation name = English name followed by numerical value of charge written as Roman numeral in parentheses (no spaces)
Transition metal Cr2+ chromium(II) Cr3+ chromium(III)
Naming Ionic Compounds
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Anions: Monatomic anions named by adding
“–ide” suffix to stem name for element
Polyatomic ions use names in Table 3.5
Naming Ionic Compounds
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Learning Check: Name The Following
K2O
NH4ClO3
Mg(C2H3O2)2
Cr2O3
ZnBr2
potassium oxide
ammonium chlorate
magnesium acetate
chromium(III) oxide
zinc bromide
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Learning Check: Determine The Formula
Calcium hydroxide Ca(OH)2
Manganese(II) bromide MnBr2
Ammonium phosphate (NH4)3PO4
Mercury(I) nitride (Hg2)3N2
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!
Which is the correct name for Cu2S?
A. copper sulfide B. copper(II) sulfideC. copper(II) sulfate
D. copper(I) sulfide E. copper(I) sulfite
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!Which is the correct formula for ammonium sulfite?
a) NH4SO3
b) (NH4)2SO3
c) (NH4)2SO4
d) NH4S
e) (NH4)2S
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Naming Hydrates Ionic compounds
Crystals contain water molecules Fixed proportions relative to ionic substance
Naming Name ionic compound Give number of water molecules in formula
using Greek prefixes
62
mono- = 1 hexa- = 6
di- = 2 hepta-
= 7
tri- = 3 octa- = 8
tetra- = 4 nona- = 9
penta-
= 5 deca- = 10
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Learning Check: Naming Hydrates CaSO4 · 2H2O
calcium sulfate dihydrate CoCl2 · 6H2O
cobalt(II) chloride hexahydrate FeI3 · 3H2O
iron(III) iodide trihydrate
63
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!What is the correct formula for copper(II) sulfate pentahydrate?
A.CuSO4 · 6H2O
B.CuSO3 · 5H2O
C.CoSO4 · 4H2O
D.CoSO3 · 5H2O
E.CuSO4 · 5H2O
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Molecular CompoundsMolecules
Electrically neutral particle Consists of two or more atoms
Chemical bonds Attractions that hold atoms together in
molecules Arise from sharing electrons between 2 atoms Group of atoms that make up molecule
behave as single particle
Molecular formulas Describe composition of molecule Specify # of each type of atom present 65
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Molecules vs. Ionic CompoundsMolecules
Discrete unit Water = 2 hydrogen atoms bonded to 1 oxygen
atom
Ionic Compounds Ions packed as close as possible to each other
Sodium chloride =Each cation has 6 anions; each anion has 6 cations
No one ion “belongs” to another
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Molecular Compounds Formed when nonmetals combine
C + O2 CO2 2H2 + O2 2H2O
Millions of compounds can form from a few non-metals
Organic chemistry & Biochemistry Deal with chemistry of carbon + H, N & O
A few compounds have only 2 atoms Diatomics: H2, O2, Cl2, HF, NO
Most molecules are far more complex Sucrose (C12H22O11) urea (CON2H4)
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Hydrogen-containing CompoundsNonmetal hydrides
Molecule containing nonmetal + hydrogen Number of hydrogens that combine with
nonmetal = number of spaces from nonmetal to noble gas in periodic table
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N O F Ne
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
3-D Shapes of Molecules Space filling models
Used to give shapes of simple nonmetal hydrides
Blue = nitrogen Red = water Yellow = fluorine White = hydrogen
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Organic Compounds Carbon compounds
Carbon + hydrogen, oxygen, & nitrogen
Originally thought these compounds only came from living organisms Now more general
Hydrocarbons Simplest organic compounds Contain only C & H Always have ratio of atoms CnH2n+2
Named using prefix designating number of C atoms
All have –ane suffix70
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Table
3.8
Hydrocarbons Belonging to the Alkane Series
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Alkanes Boiling point increases as number of
carbon atoms increases Space filling models of alkanes
Black = carbon White = hydrogen
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!
Which is the correct name for C4H10?
A. methane B. ethane C. propane D. pentane E. butane
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Other HydrocarbonsAlkenes
Hydrocarbons with two less H’s than alkanes CnH2n
Name = number prefix + ene
Ex. C2H4 = ethene (ethylene)
Alkynes Hydrocarbons with four fewer H’s than alkanes CnH2n – 2
Name = number prefix + ene
Ex. C2H2 = ethyne (acetylene)74
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Other Organic Compounds Hydrocarbons are basic building
blocks of organic chemistry Many other classes of
compounds derived from
them
Alcohols Replace H in alkane with -OH group Name = number prefix + anol
Ex. CH3OH = methanol (methyl alcohol)
C2H5OH = ethanol (ethyl alcohol)
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!
What is the name of C4H9OH?
A. hexanolB. propanol C. pentanol D.tetranol E. butanol
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Writing Formulas for Organic CompoundsMolecular formula
Indicates # of each type of atom in moleculeEx. C2H6 for ethane or C3H8 for propane Order of atoms
Carbon | Hydrogen | Other atoms alphabetically
Ex. sucrose is C12H22O11
Emphasize alcohol – write OH group last C2H5OH
Structural formula Indicate how carbon atoms are connected Ethane = CH3CH3
Propane = CH3CH2CH377
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!Octane is a hydrocarbon with 8 C atoms that is the major component of gasoline. What is the correct molecular formula for octane?
A.C8H14
B.C8H16
C.C8H18
D.C8H17OH
E.C8H15OH
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!What is the correct structural formula for octane?
a)CH3CH2CH2CH2CH2CH2CH2CH3
b)CH3CH2CH2CH2CH2CH2CH3
c)C8H18
d)CH3CH2CH2CH2CH2CH2CH2CH2CH3
e)CH3CH2CH2CH2CH2CH2CH2CH2OH
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Nomenclature of Molecular Compounds Goal is a name that translates clearly into
molecular formula
Naming Binary Molecular Compounds Which 2 elements present? How many of each?
Format: First element in formula
Use English name Second element
Use stem & append suffix –ide Use Greek number prefixes to specify how
many atoms of each element 80
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Naming Binary Molecular Compounds1. hydrogen chloride
2. phosphorous pentachloride
3. triselenium dinitride
Mono always omitted on 1st element Often omitted on 2nd element unless more
than one combination of same 2 elementsEx. Carbon monoxide CO Carbon dioxide CO2
When prefix ends in vowel similar to start of element name, drop prefix vowel
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1 H 1 Cl HCl
1 P 5Cl PCl5
3 Se 2N Se3N2
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Learning Check: Name EachFormat:
Number prefix + 1st element name Number prefix + stem + –ide for 2nd
element
AsF3 =
HBr = N2O4 =
N2O5 =
CO = CO2 =
arsenic trifluoride
hydrogen bromide
dinitrogen tetroxide
dinitrogen pentoxide
carbon monoxide
carbon dioxide
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!
Which is the correct formula for nitrogen triiodide?
A.N3I
B.NI3
C.NIO3
D.N(IO3)3
E.none of the above
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!
Which is the correct name for P4O10?
A. phosphorus oxide B. phosphorous decoxideC. tetraphosphorus decoxideD. tetraphosphorus oxideE. decoxygen tetraphosphide
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Exceptions to Naming Binary MoleculesBinary compounds of nonmetals +
hydrogen No prefixes to be used Get number of hydrogens for each nonmetal
from periodic table Hydrogen sulfide = H2S
Hydrogen telluride = H2Te
Molecules with Common Names Some molecules have names that predate IUPAC
systematic names
Water H2O ▪ Sucrose C12H22O11
Ammonia NH3 ▪ Phosphine PH385
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Summary of Naming
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