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Chapter 2: The Components of Matter
2.1: Elements, Compounds, and Mixtures: An Atomic Overview 2.2: The Observations That Led to an Atomic View of Matter 2.3: Dalton’s Atomic Theory 2.4: The Observations That Led to the Nuclear Atom Model 2.5: The Atomic Theory Today 2.6: Elements: A First Look at the Periodic Table 2.7: Compounds: Introduction to Bonding 2.8: Compounds: Formulas, Names, and Masses 2.9: Mixtures: Classification and Separation
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Fig. 2.1
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Definitions for Components of Matter
Pure Substances - Their compositions are fixed! Elements and compounds are examples of Pure Substances. Element - Is the simplest type of substance with unique physical and chemical properties. An element consists of only one type of atom. It cannot be broken down into any simpler substances by physical or chemical means. Molecule - Is a structure that is consisting of two or more atoms that are chemically bound together and thus behaves as an independent unit. Compound - Is a substance composed of two or more elements that are chemically combined. Mixture - Is a group of two or more elements and/or compounds that are physically intermingled.
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Fig. 2.2
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(p. 43)
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Separating a Mixture Fig. 2.3
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Fig. 2.4
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Laws of Mass Conservation & Definite Composition
Law of Mass conservation: The total mass of substances does not change during a chemical reaction. Law of Definite ( or constant ) composition: No matter what its source, a particular chemical compound is composed of the same elements in the same parts (fractions) by mass.
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The Meaning of Mass Fraction and Mass Percent
Fig. 2.5
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Mass Percent Composition of Na2SO4
Na2SO4 = 2 atoms of Sodium + 1 atom of Sulfur + 4 atoms of Oxygen Elemental masses Percent of each Element 2 x Na = 2 x = 45.98 1 x S = 1 x = 32.07 4 x O = 4 x = 64.00 142.05 Check % Na + % S + % O = 100% 32.37% % % = %
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Mass Percent Composition of Na2SO4
Na2SO4 = 2 atoms of Sodium + 1 atom of Sulfur + 4 atoms of Oxygen Elemental masses Percent of each Element 2 x Na = 2 x = 45.98 %Na = Mass Na / Total mass x 100% % Na = (45.98 / ) x 100% =32.37% % S = Mass S / Total mass x 100% % S = (32.07 / ) x 100% = 22.58% % O = Mass O / Total mass x 100% % O = (64.00 / ) x 100% = 45.05% 1 x S = 1 x = 32.07 4 x O = 4 x = 64.00 142.05 Check % Na + % S + % O = 100% 32.37% % % = %
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Calculating the Mass of an Element in a Compound Ammonium Nitrate
How much Nitrogen is in 455 kg of Ammonium Nitrate? Ammonium Nitrate = NH4NO3 The Formula Mass of Cpd is: 4 x H = 4 x = g 2 x N = 2 X = g 3 x O = 3 x = g Therefore gm Nitrogen/ gm Cpd g
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Calculating the Mass of an Element in a Compound Ammonium Nitrate
How much Nitrogen is in 455 kg of Ammonium Nitrate? Ammonium Nitrate = NH4NO3 The Formula Mass of Cpd is: 4 x H = 4 x = g 2 x N = 2 X = g 3 x O = 3 x = g Therefore gm Nitrogen/ gm Cpd 28.02 g Nitrogen g = g N / g Cpd g Cpd 455 kg x 1000g / kg = 455,000 g NH4NO3 455,000 g Cpd x g N / g Cpd = 1.59 x 105 g Nitrogen 28.02 kg Nitrogen or: 455 kg NH4NO3 X = 159 kg Nitrogen kg NH4NO4
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Fig. 2.7
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Law of Multiple Proportions
If elements A and B react to form two compounds, the different masses of B that combine with a fixed mass of A can be expressed as a ratio of small whole numbers: Example: Nitrogen Oxides I & II Nitrogen Oxide I : 46.68% Nitrogen and 53.32% Oxygen Nitrogen Oxide II : 30.45% Nitrogen and 69.55% Oxygen in 100 g of each Compound: g O = g & g g N = g & g g O /g N = & =
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Dalton’s Atomic Theory
1. All matter consists of atoms. 2. Atoms of one element cannot be converted into atoms of another element. 3. Atoms of an element are identical in mass and other properties and are different from atoms of any other element. 4. Compounds result from the chemical combination of a specific ratio of atoms of different elements.
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The Combining Volumes of Hydrogen and Oxygen in the Formation of Water Vapor
Fig. 2.8
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Fig. 2.9
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Fig. 2.11
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Rutherford Experiment
Alpha particles bombarding the atom. Rationale - to study the internal structure of the atom, and to know more about the mass distribution in the atom! Bombarded a thin Gold foil with Alpha particles from Radium.
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Fig. 2.12
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Ernest Rutherford (1871-1937) Won the Nobel Prize in Chemistry in 1908
“It was quite the most incredible event..... It was almost as if a gunner were to fire a shell at a piece of tissue and the shell bounced right back!!!!! ”
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Fig. 2.13
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Properties of the Subatomic Particles
Name Charge Mass Location (Symbol) Relative Absolute Relative(amu) Absolute In Atom Proton x C* x g Nucleus (P +) Neutron x g Nucleus (n o) Electron x C* x 10-28g Outside (e -) Nucleus * the coulomb (C) is the SI unit of Charge Table 2.2 (p. 53)
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Atomic Definitions I: Symbols, Isotopes,Numbers
X The Nuclear Symbol of the Atom, or Isotope Z X = Atomic symbol of the element, or element symbol A = The Mass number; A = Z + N Z = The Atomic Number, the Number of Protons in the Nucleus N = The Number of Neutrons in the Nucleus Isotopes = atoms of an element with the same number of protons, but different numbers of Neutrons in the Nucleus
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Depicting the Atom Fig. 2.14
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Neutral ATOMS 51 Cr = P+ (24), e- (24), N (27)
239 Pu = P+(94), e- (94), N (145) 15 N = P+(7), e-(7), N(8) 56 Fe = P+(26), e-(26), N (50) 235 U =P+(92), e-(92), N (143)
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Atomic Definitions II: AMU, Dalton, 12C Std.
Atomic mass Unit (AMU) = 1/12 the mass of a carbon - 12 atom on this scale Hydrogen has a mass of AMU. Dalton (D) = The new name for the Atomic Mass Unit, one dalton = one Atomic Mass Unit on this scale, 12C has a mass of daltons. Isotopic Mass = The relative mass of an Isotope relative to the Isotope 12C the chosen standard. Atomic Mass = “Atomic Weight” of an element is the average of the masses of its naturally occurring isotopes weighted according to their abundances.
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Isotopes of Hydrogen 11H 1 Proton 0 Neutrons 99.985 % 1.00782503 amu
21H (D) 1 Proton Neutron % amu 31H (T) 1 Proton Neutrons The average mass of Hydrogen is amu 3H is Radioactive with a half life of 12 years. H2O Normal water “light water “ mass = 18.0 g/mole , BP = C D2O Heavy water mass = 20.0 g/mole , BP = C
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Element #8 : Oxygen, Isotopes
168O Protons Neutrons 99.759% amu 178O Protons Neutrons 0.037% amu 188O Protons Neutrons 0.204 % amu
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Formation of a Positively Charged Neon Particle in a Mass Spectrometer
Fig. 2.A
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Fig. 2.B part A
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Calculating the “Average” Atomic Mass of an Element
Problem: Calculate the average atomic mass of Magnesium! Magnesium Has three stable isotopes, 24Mg ( 78.7%); 25Mg (10.2%); 26Mg (11.1%). 24Mg (78.7%) amu x = amu 25Mg (10.2%) amu x = amu 26Mg (11.1%) amu x = amu amu With Significant Digits = amu
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Calculate the Average Atomic Mass of Zirconium, Element #40
Zirconium has five stable isotopes: 90Zr, 91Zr, 92Zr, 94Zr, 96Zr. Isotope (% abd.) Mass (amu) (%) Fractional Mass 90Zr (51.45%) amu X = amu 91Zr (11.27%) amu X = amu 92Zr (17.17%) amu X = amu 94Zr (17.33%) amu X = amu 96Zr (2.78%) amu X = amu amu With Significant Digits = amu
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Problem: Calculate the abundance of the two Bromine isotopes:
79Br = g/mol and 81Br = g/mol , given that the average mass of Bromine is g/mol. Plan: Let the abundance of 79Br = X and of 81Br = Y and X + Y = 1.0 Solution: X( ) + Y( ) = X + Y = therefore X = Y ( Y)( ) + Y( ) = Y Y = Y = or Y = X = Y = = %X = % 79Br = x 100% = 50.67% = 79Br %Y = % 81Br = x 100% = 49.33% = 81Br
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Modern Reassessment of the Atomic Theory
1. All matter is composed of atoms. Although atoms are composed of smaller particles (electrons, protons, and neutrons), the atom is the smallest body that retains the unique identity of the element. 2. Atoms of one element cannot be converted into atoms of another element in a chemical reaction. Elements can only be converted into other elements in Nuclear reactions in which protons are changed. 3. All atoms of an element have the same number of protons and electrons, which determines the chemical behavior of the element. Isotopes of an element differ in the number of neutrons, and thus in mass number, but a sample of the element is treated as though its atoms have an average mass. 4. Compounds are formed by the chemical combination of two or more elements in specific ratios, as originally stated by Dalton.
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Definitions ELEMENT - A substance that cannot be separated into simpler substances by chemical means COMPOUND - A substance composed of atoms of two or more elements chemically united in fixed proportions PERIODIC TABLE - “MENDELEEV TABLE” - A tabular arrangement of the elements, vertical groups or families of elements based upon their chemical properties - actually combining ratios with oxygen
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Fig. 2.16
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Fig. 2.17
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The Periodic Table of the Elements Most Probable Oxidation State
+1 H +2 +3 +_4 - 3 - 2 - 1 He Li Be B C N O F Ne Na Mg +3 +4 +5 +1 + 2 Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Zr Nb Ag I Y Mo Tc Ru Rh Pd Cd In Sn Sb Te Xe Ba Au Hg Cs La Hf Ta W Re Os Ir Pt Tl Pb Bi Po At Rn Fr Ra Ac Rf Du Sg Bo Ha Me +3 Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr +3
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Newly Discovered Elements
1994 Revised IUPAC Slate Atomic No. ACS Slate IUPAC Slate Rutherfordium Dubnium Rutherfordium Hahnium Joliotium Dubnium Seaborgium Rutherfordium Seaborgium Neilsbohrium Bohrium Bohrium Hassium Hahnium Hassium Meitnerium Meitnerium Meitnerium ? ? Labs ? ? GSI Final Slate 9/12/97 ? ? GSI
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Groups in the Periodic Table
Main Group Elements (Vertical Groups) Group IA - Alkali Metals Group IIA - Alkaline Earth Metals Group IIIA - Boron Family Group IVA - Carbon Family Group VA - Nitrogen Family Group VIA - Oxygen Family (Calcogens) Group VIIA - Halogens Group VIIIA - Noble Gases Other Groups ( Vertical and Horizontal Groups) Group IB - 8B - Transition Metals Period 6 Group - Lanthanides (Rare Earth Elements) Period 7 Group - Actinides
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The Periodic Table of the Elements
Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Ac Rf Du Sg Bo Ha Me Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Th Pa Np Pu Am Cm Bk Cf Es Fm Md No Lr U The Alkali Metals The Halogens The Alkaline Earth Metals The Noble Gases
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The Periodic Table of the Elements
Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Ac Rf Du Sg Bo Ha Me Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Boron family Nitrogen family Carbon Family Oxygen Family
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The Periodic Table of the Elements
Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Ac Rf Du Sg Bo Ha Me The Transition Metals Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Lanthanides: The Rare Earth Elements The Actinides
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The Periodic Table of the Elements
Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Ac Rf Du Sg Bo Ha Me Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Metals Semi - metals Metalloids Non Metals
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Fig. 2.18
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Fig. 2.19
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Fig. 2.20
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Predicting the Ion an Element Will Form in Chemical Reactions
Problem: What monoatomic ions will each of the elements form? (a) Barium(z=56) (b) Sulfur(z=16) (c) Titanium(z =22) (d) Fluorine(z=9) Plan: We use the “z” value to find the element in the periodic table and which is the nearest noble gas. Elements that lie after a noble gas will loose electrons, and those before a noble gas will gain electrons. Solution: (a) Ba+2, Barium is an alkaline earth element, Group 2A, and is expected to loose two electrons to attain the same number of electrons as the noble gas Xenon! (b) S -2, Sulfur is in the Oxygen family, Group 6A, and is expected to gain two electrons to attain the same number of electrons as the noble gas Argon! (c) Ti+4, Titanium is in Group 4B, and is expected to loose 4 electrons to attain the same number of electrons as the noble gas Argon! (d) F -, Fluorine is in a halogen, Group 7A, and is expected to gain one electron, to attain the same number of electrons as the noble gas Neon!
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Chemical Compounds and Bonds
Chemical Bonds - The electrostatic forces that hold the atoms of elements together in the compound. Covalent Compounds - Electrons are shared between atoms of different elements to form Covalent Cpds. Ionic Compounds - Electrons are transferred from one atom to another to form Ionic Cpds. “Cations” - Metal atoms lose electrons to form “ + ” ions. “Anions” - Nonmetal atoms gain electrons to form “ - ” ions. Mono-atomic ions form binary ionic compounds
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Formation of a Covalent Bond between Two Hydrogen Atoms
Fig. 2.21
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A Polyatomic Ion Fig. 2.22
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Chemical Formulas Empirical Formula - Shows the relative number of atoms of each element in the compound. It is the simplest formula, and is derived from masses of the elements. Molecular Formula - Shows the actual number of atoms of each element in the molecule of the compound. Structural Formula - Shows the actual number of atoms, and the bonds between them ; that is, the arrangement of atoms in the molecule.
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Fig. 2.23
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Charge Formula Name Charge Formula Name
Table 2.3 (p. 67) Common Monoatomic Ions Cations Anions Charge Formula Name Charge Formula Name H hydrogen H hydride Li lithium F fluoride Na sodium Cl chloride K potassium Br bromide Cs cesium I iodide Ag silver Mg magnesium O oxide Ca calcium S sulfide Sr strontium Ba barium Zn zinc Cd cadmium Al aluminum N nitride Listed by charge; those in boldface are most common
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Give the Name and Chemical Formulas of the Compounds Formed from the Following Pairs of Elements
a) Sodium and Oxygen Na2O Sodium Oxide b) Zinc and Chlorine ZnCl Zinc Chloride c) Calcium and Fluorine CaF Calcium Fluoride d) Strontium and Nitrogen Sr3N Strontium Nitride e) Hydrogen and Iodine HI Hydrogen Iodide f) Scandium and Sulfur Sc2S Scandium Sulfide
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Some Metals That Form More than One Oxidation State
Element Ion Formula Systematic Name Common Name Chromium Cr Chromium (II) Chromous Cr Chromium (III) Chromic Cobalt Co Cobalt (II) Co Cobalt (III) Copper Cu Copper (I) Cuprous Cu Copper (II) Cupic Iron Fe Iron (II) Ferrous Fe Iron (III) Ferric Lead Pb Lead (II) Pb Lead (IV) Manganese Mn Manganese (II) Mn Manganese (III) Mercury Hg Mercury (I) Mercurous Hg Mercury (II) Mercuric Tin Sn Tin (II) Stannous Sn Tin (IV) Stannic Table 2.4 (p. 69)
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Some Common Polyatomic Ions
Formula Name Formula Name Cations Anions Ctd. NH Ammonium H3O Hydronium MnO Permanganate CO Carbonate HCO Hydrogen Carbonate CrO Chromate Cr2O Dichromate O Peroxide PO Phosphate HPO Hydrogen Phosphate H2PO Dihydrogen Phosphate SO Sulfite SO Sulfate HSO Hydrogen Sulfate Anions CH3COO Acetate CN Cyanide OH Hydroxide ClO Hypochlorite ClO Chlorite ClO Chlorate ClO Perchlorate NO Nitrite NO Nitrate
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Give the systematic names for the formulas or the formulas
Determining Names and Formulas of Ionic Com-pounds of Elements That Form More than One Ion Give the systematic names for the formulas or the formulas for the names of the following compounds. a) Iron III Sulfide - Fe is +3, and S is -2 therefore the compound is: Fe2S3 b) CoF the anion is Fluoride (F -1) and there are two F -1, the cation is Cobalt and it must be Co+2 therefore the compound is: Cobalt (II) Fluoride c) Stannic Oxide - Stannic is the common name for Tin (IV), Sn+4, the Oxide ion is O-2, therefore the formula of the compound is: SnO2 d) NiCl3 - The anion is chloride (Cl-1), there are three anions, so the Nickel cation is Ni+3, therefore the name of the compound is: Nickel (III) Chloride
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Rules for Families of Oxoanions
Families with Two Oxoanions The ion with more O atoms takes the nonmetal root and the suffix “-ate”. The ion with fewer O atoms takes the nonmetal root and the suffix “-ite”. Families with Four Oxoanions (usually a Halogen) The ion with most O atoms has the prefix “per-”, the nonmetal root and the suffix “-ate”. The ion with one less O atom has just the suffix “-ate”. The ion with two less O atoms has the just the suffix “-ite”. The ion with three less O atoms has the prefix “hypo-” and the suffix “-ite”.
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Naming Oxoanions - Examples
Prefixes Root Suffixes Chlorine Bromine Iodine per “ ” ate perchlorate perbromate periodate [ ClO4-] [ BrO4-] [ IO4-] “ ” ate chlorate bromate iodate [ ClO3-] [BrO3-] [ IO3-] “ ” ite chlorite bromite iodite [ ClO2-] [ BrO2-] [ IO2-] hypo “ ” ite hypochlorite hypobromite hypoiodite [ ClO -] [ BrO -] [ IO -] No. of O atoms
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Numerical Prefixes for Hydrates and Binary Covalent Compounds
NUMBER PREFIX NUMBER PREFIX mono hexa- di hepta- tri octa- tetra nona- penta deca- Table 2.6 (p. 70)
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Compounds Containing Water Molecules
Hydrates Compounds Containing Water Molecules MgSO4 7H2O Magnesium Sulfate heptahydrate CaSO4 2H2O Calcium Sulfate dihydrate Ba(OH)2 8H2O Barium Hydroxide octahydrate CuSO4 5H2O Copper II Sulfate pentahydrate Na2CO H2O Sodium Carbonate decahydrate
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Examples of Names and Formulas of Oxoanions and Their Compounds - I
KNO Potassium Nitrite BaSO3 Barium Sulfite Mg(NO3)2 Magnesium Nitrate Na2SO4 Sodium Sulfate LiClO4 Lithium Perchlorate Ca(BrO)2 Calcium Hypobromite NaClO3 Sodium Chlorate Al(IO2) Aluminum Iodite RbClO2 Rubidium Chlorite KBrO3 Potassium Bromate CsClO Cesium Hypochlotite LiIO4 Lithium Periodate
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Examples of Names and Formulas of Oxoanions and Their Compounds - II
Calcium Nitrate Ca(NO3) Ammonium Sulfite (NH4)2SO3 Strontium Sulfate SrSO Lithium Nitrite LiNO2 Potassium Hypochlorite KClO Lithium Perbromate LiBrO4 Rubidium Chlorate RbClO Calcium Iodite Ca(IO2)2 Ammonium Chlorite NH4ClO Boron Bromate B(BrO3)3 Sodium Perchlorate NaClO Magnesium Hypoiodite Mg(IO)2
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Determining Names and Formulas of Ionic
Compounds Containing Polyatomic Ions a) BaCl2 Ba+2 is the cation Barium, Cl- is the Chloride anion. There are five water molecules therefore the name is: Barium Chloride Pentahydrate 5 H2O b) Magnesium Perchlorate Magnesium is the Mg+2 cation, and perchlorate is the ClO4- anion, therefore we need two perchlorate anions for each Mg cation therefore the formula is: Mg( ClO4)2 c) (NH4)2SO NH4+ is the ammonium ion, and SO3-2 is the sulfite anion, therefore the name is: Ammonium Sulfite d) Calcium Nitrate Calcium is the Ca+2 cation, and nitrate is the NO3- anion, therefore the formula is: Ca(NO3)2
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Naming Acids 1) Binary acids solutions form when certain gaseous compounds dissolve in water. For example, when gaseous hydrogen chloride (HCl) dissolves in water, it forms a solution called hydrochloric acid. Prefix hydro- + anion nonmetal root + suffix -ic + the word acid hydrochloric acid 2) Oxoacid names are similar to those of the oxoanions, except for two suffix changes: Anion “-ate” suffix becomes an “-ic” suffix in the acid. Anion “-ite” suffix becomes an “-ous” suffix in the acid. The oxoanion prefixes “hypo-” and “per-” are retained. Thus, BrO4- is perbromate, and HBrO4 is perbromic acid; IO2- is iodite, and HIO2 is iodous acid.
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Determining Names and Formulas of Anions and Acids
Problem: Name the following anions and give the names and formulas of the acid solutions derived from them: a) I b) BrO c) SO d) NO e) CN - Solution: a) The anion is Iodide; and the acid is Hydroiodic acid, HI b) The anion is Bromite; and the acid is Bromous acid, HBrO2 c) The anion is Sulfite; and the acid is Sulfurous acid, H2SO3 d) The anion is Nitrate; and the acid is Nitric acid, HNO3 e) The anion is Cyanide; and the acid is Hydrocyanic acid, HCN
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Names and Formulas of Binary Covalent Compounds
1) The element with the lower group number in the periodic table is the first word in the name; the element with the higher group number is the second word. (Important exception: When the compound contains oxygen and a halogen, the halogen is named first.) 2) If both elements are in the same group, the one with the higher period number is named first. 3) The second element is named with its root and the suffix “-ide.” 4) Covalent compounds have Greek numerical prefixes (table 2.6) to indicate the number of atoms of each element in the compound. The first word has a prefix only when more than one atom of the element is present; the second word always has a numerical prefix.
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Determining Names and Formulas of Binary Covalent Compounds
Problem: What are the name or Chemical formulas of the following Chemical compounds: a) Carbon dioxide b) PCl3 c) Give the name and chemical formula of the compound formed from two P atoms and five O atoms. Solution: a) The prefix “di-” means “two.” The formula is CO2 b) P is the symbol for phosphorous; there are three chlorine atoms which require the prefix “tri-.” The name of the compound is: phosphorous trichloride c) P comes first in the name (lower group number). The compound is diphosphorous pentaoxide ( commonly called “phosphorous pentaoxide”)
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Naming Alkanes Alkanes are hydrocarbons that are called “saturated” hydrocarbons, they contain only single bonds, no multiple bonds ! Alkanes have the general formula C n H 2n+2 Each carbon atom has four bonds to others atoms ! The names for alkanes all end in -ane Alkanes are found in three distinct groups: a) Straight chain hydrocarbons b) Branched chain hydrocarbons c) Cyclic hydrocarbons
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The First 10 Straight-Chain Alkanes
Name Formula Structural Formulas H H H Methane CH4 Ethane C2H6 Propane C3H8 Butane C4H10 Pentane C5H12 Hexane C6H14 Heptane C7H16 Octane C8H18 Nonane C9H20 Decane C10H22 H C H H C C H H H H CH3-CH2-CH3 CH3-(CH2)2-CH3 CH3-(CH2)3-CH3 CH3-(CH2)4-CH3 CH3-(CH2)5-CH3 CH3-(CH2)6-CH3 CH3-(CH2)7-CH3 Table 2.7 CH3-(CH2)8-CH3
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Calculating the Molecular Mass of a Compound
Problem: Using the data in the periodic table, calculate the molecular mass of the following compounds: a) Tetraphosphorous decoxide b) Ammonium sulfate Plan: We first write the formula, then multiply the number of atoms (or ions) of each element by its atomic mass, and find the sum. Solution: a) The formula is P4O10. Molecular mass = (4 x atomic mass of P ) +(10 x atomic mass of O ) = ( 4 x amu) + ( 10 x amu) = = amu b) The formula is (NH4)2SO4 Molecular mass = ( 2 x atomic mass of N ) + ( 8 x atomic mass of H) + ( 1 x atomic mass of S ) + ( 4 x atomic mass of O) = ( 2 x amu) + ( 8 x amu) + ( 1 x amu) + ( 4 x amu) = amu = amu
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Calculate the Molecular Mass of Glucose: C6H12O6
Carbon x g/mol = g Hydrogen 12 x g/mol = g Oxygen x g/mol = g g
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Fig. 2.25
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Mixtures Heterogeneous mixtures : has one or more visible
boundaries between the components. Homogeneous mixtures : has no visible boundaries because the components are mixed as individual atoms, ions, and molecules. Solutions : A homogeneous mixture is also called a solution. Solutions in water are called aqueous solutions, and are very important in chemistry. Although we normally think of solutions as liquids, they can exist in all three physical states.
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Separating Mixtures Filtration : Separates components of a mixture based upon differences in particle size. Normally separating a precipitate from a solution, or particles from an air stream. Crystallization : Separation is based upon differences in solubility of components in a mixture. Distillation : separation is based upon differences in volatility. Extraction : Separation is based upon differences in solubility in different solvents (major material). Chromatography : Separation is based upon differences in solubility in a solvent versus a stationary phase.
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Filtration Fig. 2.D
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Crystallization Fig. 2.E
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Fig. 2.F
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Fig. 2.G
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Procedure for Column Chromatography
Fig. 2.H
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Fig. 2.I A&B
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