CHEM115 General Chemistry I

CHEM115 General Chemistry I
Contacting me: & Pronto Homework: Register your ID with Wiley, then enter your book code WileyPLUS: RESOURCES Reading content Chapter Opener 2.1 Elements and Atoms are Described by Dalton's Atomic Theory 2.2 Atoms are Composed of Subatomic Particles 2.3 The Periodic Table is used to Organize and Correlate Facts 2.4 Elements can be Metals, Nonmetals, or Metalloids 2.5 Formulas and Equations Describe Substances and their Reactions 2.6 Molecular Compounds Contain Neutral Particles Called Molecules 2.7 Ionic Compounds are Composed of Charged Particles called Ions 2.8 The Formulas of Many Ionic Compounds can be Predicted 2.9 Molecular and Ionic Compounds are Named following a System Summary Tools for Problem Solving Questions, Problems, and Exercises Glossary Office Hours Videos Chapter 2, Problem 76 Chapter 2, Problem 83 Chapter 2, Problem 99a Chapter 2, Problem 99b Chapter 2, Problem 99c Chapter 2, Problem 104a Chapter 2, Problem 104b Chapter 2, Problem 104c Chapter 2, Problem 104d Chapter 2, Problem 104e Chapter 2, Problem 120a Chapter 2, Problem 120b Chapter 2, Problem 120c Chapter 2, Problem 120d Chapter 2, Problem 120e Chapter 2, Problem 120f Chapter 2, Problem 120g Chapter 2, Problem 129 Chapter 2, Problem 130 Chapter 2, Problem 132 Chapter 2, Problem 138 ChemFAQ ChemFAQ - Chapter 2 Interactive LearningWare 2.86. Interactive LearningWare 2.88. Interactive LearningWare Video Demonstrations Sodium and chlorine Additional Resources 3D Molecules Audio Pronunciation Guide

Ch 2. Elements, Compounds and Chemical Reactions
Brady & Senese, 5th Ed.

2.1. Elements and atoms are described by Dalton’s atomic theory
Chemical Laws The law of conservation of mass - in a chemical reaction, the mass of the reactants (starting materials) will equal the mass of resulting products Implication: reactions involve the re-organization of materials. The law of definite proportions- the ratio of masses of each element is fixed for a given compound Implication: Each atom has a fixed specific mass, thus in unique combinations, the mass ratio is specific Chem FAQs: What is a mass balance? What is the law of conservation of mass? How can I use the Law of Definite Proportions to recognize a compound? 2.1. Elements and atoms are described by Dalton’s atomic theory

Learning Check: Magnesium burns in oxygen to form magnesium oxide. If g of Mg are consumed and g of MgO are produced, what mass of oxygen was consumed? 2.1. Elements and atoms are described by Dalton’s atomic theory

23/04/2017 Question: Two compounds of copper and chlorine exist with one having twice as much chlorine per gram of copper as the other. This is evidence of which law? a: Conservation of Mass b: Definite Proportions c: Multiple Proportions 5

Dalton’s Atomic Theory
Matter consists of tiny particles called atoms Atoms are indestructible. In chemical reactions, the atoms rearrange but they do not themselves break apart + Chem FAQ: What is Dalton's Atomic Theory? 2.1. Elements and atoms are described by Dalton’s atomic theory

Dalton’s Atomic Theory (Cont.):
In any sample of a pure element, all the atoms are identical in mass and other properties. The atoms of different elements differ in mass and other properties. In a given compound the constituent atoms are always present in the same fixed numerical ratio. NaCl has a 1:1 atom ratio on the atomic level and larger Chem FAQ: What is Dalton's Atomic Theory? 2.1. Elements and atoms are described by Dalton’s atomic theory

John Dalton

Learning Check: In a sample of MgO, there are g Mg and g O. What mass of O would there be in a sample that contains 2.00 g of Mg? Chem FAQ: How can I use the Law of Definite Proportions to relate masses of elements in compounds? 2.1. Elements and atoms are described by Dalton’s atomic theory

Your Turn! In a sample of an unknown compound, the mass ratio of Cl to C is g Cl to 4.00 g C. In another sample, there are g of Cl. What mass of C would be in this sample? g 6.52 g 0.153 g g None of these 2.1. Elements and atoms are described by Dalton’s atomic theory

23/04/2017 Question: 9 grams of water contain 1 gram of hydrogen. How many grams of water contain 3 grams of hydrogen? a: 1/3 gram b: 3 grams c: 9 grams d: 27 grams 11

The Law Of Multiple Proportions
When two elements form more than one compound, the different masses of one element that combine with the same mass of the other element are in the ratio of small whole numbers. cements the idea that atoms react as complete (whole) particles. chemical formulas indicate whole numbers of atoms- not fractions Chem FAQ: What is the law of multiple proportions? 2.1. Elements and atoms are described by Dalton’s atomic theory

Using The Law Of Multiple Proportions
sulfur sulfur dioxide trioxide Mass S g g Mass O g g Use these data to prove the law of multiple proportions FIG. 2.1 Oxygen compounds of sulfur demonstrate the law of multiple proportions. Illustrated here are molecules of sulfur trioxide and sulfur dioxide. Each has one sulfur atom, and therefore the same mass of sulfur. The oxygen ratio is 3 to 2, both by atoms and by mass. 2.1. Elements and atoms are described by Dalton’s atomic theory

Your Turn! Two substances are formed from A and B. AB and A2B3. If the mass ratio of A/B in AB is 3.49, what is the ratio of A/B in A2B3? 0.431 3.49 0.286 2.33 not enough information given 2.1. Elements and atoms are described by Dalton’s atomic theory

Proof Of Atoms Since the early 1980’s, the Scanning Tunneling Microscope (STM) has been used A surface can be scanned for topographical information The image for all matter shows spherical regions of matter-- atoms FIG. 2.2 Individual atoms can be imaged using a scanning tunneling microscope. This STM micrograph reveals the pattern of individual atoms of palladium deposited on a graphite surface. Palladium is a silvery white metal used in alloys such as white gold and dental crowns. Atomically resolved STM image of clean Au(100). This image is made with an Omicron Low Temperature STM and RHK Technology electronics by Erwin Rossen, Eindhoven University of Technology, Parameters: p<1e-11 mbar, T=77 K, I_setpoint=6 nA, V_bias=1 mV, Au(100) surface is Ar sputtered (1,5 kV, 2uA, 30 minutes) and annealed (500°C, 30 minutes). 2.1. Elements and atoms are described by Dalton’s atomic theory

23/04/2017 Radioactivity One of the pieces of evidence for the fact that atoms are made of smaller particles came from the work of Marie Curie ( ). She discovered radioactivity, the spontaneous disintegration of some elements into smaller pieces. 16

2.2 Atoms are composed of subatomic particles
Cathode Ray Tube (CRT) A gas filled glass tube that has electrical charge applied at both ends. Such a tube glows with light and is the precursor of the modern-day television screen. 2.2 Atoms are composed of subatomic particles

Discovery Of The Electron By JJ Thomson
In 1897, Thomson placed a magnet near CRT and noted deflection of the beam Repeated experiment with an electrical field and noted that the discharge was deflected by an electrical field toward the (+) plate Announced discovery of (-) particle, later named “electron” by Stoney 2.2 Atoms are composed of subatomic particles

Determining The Charge On An e-: Millikan
Richard Feynman said in a commencement lecture he gave at Caltech in 1974[5] We have learned a lot from experience about how to handle some of the ways we fool ourselves. One example: Millikan measured the charge on an electron by an experiment with falling oil drops, and got an answer which we now know not to be quite right. It's a little bit off because he had the incorrect value for the viscosity of air. It's interesting to look at the history of measurements of the charge of an electron, after Millikan. If you plot them as a function of time, you find that one is a little bit bigger than Millikan's, and the next one's a little bit bigger than that, and the next one's a little bit bigger than that, until finally they settle down to a number which is higher. Why didn't they discover the new number was higher right away? It's a thing that scientists are ashamed of - this history - because it's apparent that people did things like this: When they got a number that was too high above Millikan's, they thought something must be wrong - and they would look for and find a reason why something might be wrong. When they got a number close to Millikan's value they didn't look so hard. And so they eliminated the numbers that were too far off, and did other things like that. We've learned those tricks nowadays, and now we don't have that kind of a disease. 2.2 Atoms are composed of subatomic particles

Rutherford’s Alpha Scattering Experiment
Alpha particles were known to be positively charged and about 4000 times as massive as an electron. (Actually this experiment was performed by 2 post-doctoral students in Rutherford’s Lab, Geiger and Marsden) According to Rutherford, “it is almost as if you had fired a 15-inch shell at a piece of tissue paper and had it come back at you.” Most alpha rays passed right through the Au A few were deflected off at an angle 1 in bounced back towards the alpha ray source 2.2 Atoms are composed of subatomic particles

Rutherford’s Nuclear Model of the Atom
Since most of the alpha particles were not deflected, most of the atom is empty space. Since some of the particles were deflected, they encountered small particles of the same charge. Since some particles were reflected, there must be a small dense area. A good analogy of the size variation between the nucleus and the atom is that of a ping-pong ball in the Houston Astrodome. 2.2 Atoms are composed of subatomic particles

23/04/2017 The modern view of the atom was developed by Ernest Rutherford ( ). “It was about as credible as if you had fired a 15-inch artillery shell at a piece of paper and it came back and hit you” 02m11an1.mov 23

23/04/2017 Question: 24

Discovery Of The Proton
Discovered in 1918 in Ernest Rutherford’s lab Detected using a Mass Spectrometer 2.2 Atoms are composed of subatomic particles

Discovery Of The Neutron
Chadwick determined that the nuclei of light atoms could be caused to disintegrate by being bombarded by alpha particles. In collision of alpha particles with Be, a free neutron was created the presence of the neutron confirmed in 1932 2.2 Atoms are composed of subatomic particles

Symbol Mass (u) Location Charge electron (10-4) orbital 1- proton nucleus 1+ neutron 2.2 Atoms are composed of subatomic particles

Atomic Mass Dalton’s atomic theory states that atoms of an element have a constant, characteristic atomic mass or atomic weight measured in amu (u) Atomic masses are based on a standard mass, that of an atom of C 1 atom of Carbon-12 = 12 u Thus 1 u = 1/12 the mass of a Carbon-12 atom Chem FAQ: What is an atomic mass unit? 2.2 Atoms are composed of subatomic particles

Isotopes Most elements in nature are uniform mixtures of two or more kinds of atoms with slightly different masses Atoms of the same element with different masses are called isotopes For example: there are 3 isotopes of hydrogen and 4 isotopes of iron Chemically, isotopes have virtually identical properties The relative proportions of the different isotopes are essentially constant 2.2 Atoms are composed of subatomic particles

Atomic Notation An element is a substance whose atoms all contain the identical number of protons, called the atomic number (Z) Isotopes are distinguished by mass number (A): Atomic number, Z = number of protons Mass number, A = (number of protons) + (number of neutrons) Note that for atoms, A is greater than Z: the symbol is top-heavy For charge neutrality, the number of electrons and protons must be equal 2.2 Atoms are composed of subatomic particles

Example: uranium-235 Mass number, A (protons + neutrons)  Chemical Symbol  Atomic number, Z (number of protons)  235 U 92 This information can be summarized: Number of protons = 92 ( = number of electrons) Number of neutrons = 143 Atomic number (Z) = 92 Mass number (A) = = 235 Chemical symbol = U Note that the number that follows the dash is the mass number. Chem FAQ: How do I write symbols for isotopes? 2.2 Atoms are composed of subatomic particles

Question: How many neutrons are there in an atom of sulfur-33? a: 16
23/04/2017 Question: How many neutrons are there in an atom of sulfur-33? a: 16 b: 17 c: 33 d: 49 32

Question: How many electrons are there in an atom of uranium-238?
23/04/2017 Question: How many electrons are there in an atom of uranium-238? a: 92 b: 146 c: 238 d: 330 33

23/04/2017 Question: 34

Learning Check: Fill in the blanks: symbol neutrons protons electrons 60Co 81Br 2.2 Atoms are composed of subatomic particles

Your Turn! How many neutrons are there in 52Fe? 52 55 26 none of these 2.2 Atoms are composed of subatomic particles

What is the total value of:
3 quarters, two dimes and one nickel?

Learning Check: Atomic Mass
Naturally occurring chlorine is a mixture of two isotopes. In every sample of this element, 75.77% of the atoms are chlorine-35 and 24.23% are chlorine-37. The measured mass of chlorine-35 is u and that of chlorine-37 is u. Calculate the average atomic mass of chlorine. Chem FAQs: How do I calculate an average atomic mass from isotopic masses and abundances? How do I calculate isotopic masses or abundances using average atomic mass? 2.2 Atoms are composed of subatomic particles

Your Turn There are 2 isotopes of element Z. The first is 56.5% in abundance and has a mass of u. If the atomic mass is u, what is the mass of the other isotope? 156 u 44.5 u 157. u not enough information given none of these 2.2 Atoms are composed of subatomic particles

23/04/2017 Question: Copper has two stable isotopes, copper-63 and copper-65. What is the abundance of copper-65? a: 5.75% b: 27.5% c: 50% d: 72.5% e: 95.5% 40

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Problem Solving Calculate the average atomic mass of chromium of naturally occurring chromium based on the information given for its four isotopes: 4.31% 50Cr of mass amu, 83.76% 52Cr of mass amu, 9.55% 53Cr of mass amu and 2.38% 54Cr of mass amu.

Problem Solving Naturally occurring Gallium consists of two isotopes. Calculate the percent abundances of Ga-69 and Ga-71 when the atomic mass is amu and the isotopic masses are and amu respectively

2.3. The periodic table is used to organize and correlate facts
arranged in numbered rows – “periods” columns called “groups” or “families” 1A 2A 3A 4A 5A 6A 7A 8A 1 2 H He 3 4 5 6 7 8 9 10 Li Be B C N O F Ne 11 12 13 14 15 16 17 18 Na Mg 3B 4B 5B 6B 7B 8B 1B 2B Al Si P S Cl Ar 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 87 88 89 104 105 106 107 108 109 110 111 112 114 Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Uuu Uub Uuq 58 59 60 61 62 63 64 65 66 67 68 69 70 71 Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 90 91 92 93 94 95 96 97 98 99 100 101 102 103 Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Chem FAQs: Periodic Table of the Elements How do I classify elements according to group or family? 2.3. The periodic table is used to organize and correlate facts

2.3. The periodic table is used to organize and correlate facts
Summarizes chemical and physical properties of the elements Mendeleev first arranged atoms by increasing atomic mass. Noted repeating (periodic) properties Modern table is arranged by increasing atomic number (Moseley) Chem FAQs: Periodic Table of the Elements How do I classify elements according to group or family? 2.3. The periodic table is used to organize and correlate facts

Some Important Classifications:
A groups = representative elements or main group elements I A = alkali metals II A = alkaline earth metals VII A = halogens VIII = noble (also inert) gases B groups = transition elements Inner transition elements = elements 58 – 71 and 90 – 103 58 – 71 = lanthanide elements 90 – 103 = actinide elements See figure 1.15 for graphical distinction of these groups. 2.3. The periodic table is used to organize and correlate facts

The modern periodic table
FIG. 2.5 The modern periodic table. At room temperature, mercury and bromine are liquids. Eleven elements are gases including the noble gases and the diatomic gases of hydrogen, oxygen, nitrogen, fluorine, and chlorine. The remaining elements are solids. 2.3. The periodic table is used to organize and correlate facts

Metals, Nonmetals, And Metalloids
FIG. 2.7 Distribution of metals, nonmetals, metalloids among the in the periodic table. 2.4. Elements can be metals, non-metals, or metalloids

2.4. Elements can be metals, non-metals, or metalloids
Your turn! Which of the following is correct? Cu is a representative transition element Na is an alkaline earth metal Al is a semimetal in group IIIa F is a representative halogen None of these are correct 2.4. Elements can be metals, non-metals, or metalloids

2.4. Elements can be metals, non-metals, or metalloids
Properties Of Metals reflect light (have metallic luster) Can be hammered or rolled into thin sheets (are malleable) and can be drawn into wire (are ductile) Are solids at room temperature (except Hg) conduct electricity and heat 2.4. Elements can be metals, non-metals, or metalloids

Nonmetals And Metalloids
Lack the properties of metals Tend to pulverize when struck with a hammer Non-conductors of electricity and heat Many are gases, a few solids, and one liquid (Br) React with metals to form (ionic) compounds Metalloids Have properties between metals and nonmetals Chem FAQs: How do I classify elements as metals, nonmetals, or metalloids? How do I classify an element as a metal or nonmetal based on its properties? 2.4. Elements can be metals, non-metals, or metalloids

Question: Which is a fourth-period alkaline earth metal? a: K b: Ca
23/04/2017 Question: Which is a fourth-period alkaline earth metal? a: K b: Ca c: Zr d: C e: Sn 52

23/04/2017 Question: Which are almost always found in nature in pure elemental form? a: alkali metals b: inner transition metals c: noble gases d: halogens e: metalloids 53

Which is not a characteristic property of most metals? a: malleability
23/04/2017 Question: Which is not a characteristic property of most metals? a: malleability b: good electrical conductivity c: ductility d: poor heat conductivity e: luster 54

Question: Which describes a physical property? a: colorless
23/04/2017 Question: Which describes a physical property? a: colorless b: flammable c: toxic d: reactive e: corrosive 55

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23/04/2017 Question: 59

2.5. Formulas and equations describe substances and their reactions
Chemical Formulas Are symbols used to describe other elements in a compound elements and compounds Free elements are not combined with another element in a compound. Examples: Fe (iron), Na (sodium), and K (potassium) Many non-metals occur in groups of 2 (as diatomic molecules)- H, O, N, F, Cl, I, Br Some elements occur as molecules: P4, S, S8, P10, O3 , etc… 2.5. Formulas and equations describe substances and their reactions

Chemical Formulas (Cont.)
Specify the composition of a substance Fe2O3 is composed of the elements iron and oxygen in a 2:3 ratio CO(NH2)2 expands to CON2H4, but parentheses often group atoms to show the compound’s structure 2.5. Formulas and equations describe substances and their reactions

MOLECULAR FORMULAS 2 C atoms 5 H atoms 1 N atom 2 O atoms
Formula for glycine is C2H5NO2 In one molecule there are 2 C atoms 5 H atoms 1 N atom 2 O atoms

(NH4)2HPO4? a: 5 b: 6 c: 7 d: 9 e: none of these
Question: How many atoms of hydrogen are present in the formula (NH4)2HPO4? a: b: c: d: e: none of these

Hydrates Hydrates are crystals that contain water molecules, for example plaster: CaSO4 • 2H2O When all the water is removed (by heating), the solid that remains is said to be anhydrous (without water) FIG Water can be driven from hydrates by heating. (a) Blue crystals of copper sulfate pentahydrate, CuSO4·5H2O, about to be heated. (b) The hydrate readily loses water when heated. The light colored solid observed in the lower half of the test tube is pure CuSO4. CuSO4 •5H2O CuSO4 2.5. Formulas and equations describe substances and their reactions

Learning Check: Count The Atoms In A Chemical Formula
___Na, ___ C, ___ O ___N, ___H, ___S, ____O ___Mg, ___P, ____O ___Cu, ___S, ___O, ___H Na2CO3 (NH4)2SO4 Mg3(PO4)2 CuSO4•5H2O Chem FAQ: How do I count the atoms of elements in a chemical formula? 2.5. Formulas and equations describe substances and their reactions

Chemical Equations 2 HCl(aq) + CaCO3(s)  CaCl2(aq) + H2O(l) +CO2(g) HCl and CaCO3 are called reactants CaCl2, H2O,CO2 are called the products Reactants are separated from products with “” that means “yields” States matter: for solids use (s), liquids (l), gases (g), and for substances dissolved in water (aqueous solutions) use (aq). We will learn later that the behavior of the reactants differs based on their states! Chem FAQs: Chemical equation construction kit 2.5. Formulas and equations describe substances and their reactions

How many atoms are represented in each of the following expressions:
Problem Solving How many atoms are represented in each of the following expressions: 3N2O 2(NH4)2CO3 BaSO3 CuSO4•2H2O (NH4)3PO4 Sn(SCN)2 MgSO4•5H2O

Balanced Equations The number of atoms of each type must remain the same on each side of the arrow subscripts must not change- they define the identity of the substances Coefficients- numbers in front of formulas-- indicate the number of molecules of each type Balancing achieved by adjusting coefficients 2 H2 + O2 →2 H2O 2.5. Formulas and equations describe substances and their reactions

Balanced Equations Note that the number of each type of atom balances and that the coefficient applies to the entire formula Chem FAQ: Kit_chemical_equation 2.5. Formulas and equations describe substances and their reactions

Guidelines for Balancing Equations:
Balance elements other than H and O first Balance as a group any polyatomic ions that appears unchanged on both sides of the arrow Balance separately those elements that appear somewhere by themselves As a general rule you should use the smallest whole-number coefficients when writing balanced chemical equations

Balancing Equations __C3H8(g) + __ O2(g)  __CO2(g) + __ H2O(g)
__B4H10(g) + __ O2(g)  _ B2O3(g) + __H2O(g) 04m04an1.mov

Balancing Equations N2O5  N2O4 + O2 NH4NO2  N2 + H2O
KOH H3PO4  K3PO H2O NH CuO  Cu N H2O

a: P4+ F2  PF5 b: H2 + S8  H2S c: H2 + O2  H2O2 d: Li + O2  Li2O
Question: Which equation is balanced? a: P4+ F2  PF5 b: H2 + S8  H2S c: H2 + O2  H2O2 d: Li + O2  Li2O

Molecules Form When Nonmetallic Elements Combine
Molecules are neutral particles made of 2 or more atoms. Many molecular compounds contain hydrogen: Group Noble Period IVA VA VIA VIIA Gas CH NH H2O HF Ne SiH PH H2S HCl Ar GeH AsH H2Se HBr Kr SbH H2Te HI Xe Note: The number of hydrogens that combined with the nonmetal equals the number of spaces to the right we have to move to get to the noble gas 2.6 Molecular compounds contain neutral particles called molecules

2.6 Molecular compounds contain neutral particles called molecules
Alkanes Alkanes are hydrocarbons (contain only C and H) Always have a ratio of atoms CnH2n+2 Named using a prefix designating the number of C All have –ane suffix. C 1 2 3 4 5 6 7 8 9 10 Prefix Meth- Eth- Prop- But- Pent- Hex- Hept- Oct- Non- Dec- Suffix +ane Name Methane Ethane Propane 2.6 Molecular compounds contain neutral particles called molecules

Alkanes are the simplest hydrocarbons
Organic chemistry is a major specialty that deals with compounds containing mostly carbon and hydrogen Hydrocarbons contain only hydrogen and carbon and are organic compounds Alkanes are the simplest hydrocarbons General formula is CnH2n+2 1 = meth- 2 = eth- 3 = prop- 4 = but- 5 = pent- 6 = hex-

Learning Check: Name that alkane
2.6 Molecular compounds contain neutral particles called molecules

Your turn! Which of the following is heptane? C6H12 C7H14 C6H14 C7H16

Your turn! Which is the correct name for C4H10? methane ethane propane
pentane none of these

Other Organic Compounds
Alkenes- hydrocarbons with fewer H than the alkanes. CnH2n. Use the same prefixes, but have the suffix -ene. C2H4 : ___________ C3H6: _____________ Note that ethene is commonly referred to ethylene. 2.6 Molecular compounds contain neutral particles called molecules

Other Organic Compounds (Cont.)
Alcohols- Replace one H in an alkane with an -OH group Same prefixes, suffix becomes –anol CH3OH is ____________ C2H5OH is _______________ Note that ethene is commonly referred to ethylene. 2.6 Molecular compounds contain neutral particles called molecules

Your Turn! What is the name of CH3CH2CH2CH2OH? butanol propanol
pentanol tetranol none of these

Your Turn! What is a formula for heptene? C6 H12 C7H14 C6H14 C7H16
none of these

What is the formula for hexanol? C6H14 C6H13OH C6H12OH C6(OH)14
Question: What is the formula for hexanol? C6H14 C6H13OH C6H12OH C6(OH)14

2.7 Ionic compounds are composed of charged particles called ions
Positively charged ions are called cations Negatively charged ions are called anions subscripts in the formula always specify the smallest whole-number ratio of the ions needed to make a neutral combination (formula unit) See Chem FAQ: Ionic Compound Construction Kit 2 Fe3+ 3 O2- Fe O 2 3 2.7 Ionic compounds are composed of charged particles called ions

What About Ions? Number of p+ = number of e- if neutral Number of p+ < number of e- if negative Number of p+ > number of e- if positive The number of p+ never changes when ions form How does Ca form Ca2+? How is N3- formed? 2.7 Ionic compounds are composed of charged particles called ions

Learning Check: Fill in the blanks: Symbol neutrons protons electrons 60Co3+ 81Br- Chem FAQ: How do I count the number of electrons present in an atom or elemental ion? 2.7 Ionic compounds are composed of charged particles called ions

a: 12 b: 15 c: 18 d: 28 e: 34 How many electrons are there in P3-
Question: How many electrons are there in P3- a: b: c: d: e: 34

a: 36 b: 37 c: 38 d: 85 e: none of these
Question: How many protons are in Rb+ a: b: c: d: e: none of these

METALS Group A metals: charge=group# Na+ Mg2+ Al3+
Transition metals have variable charges Stock System indicates charge Iron(III) means Fe3+

NONMETALS Charge = 8-Group# C4- carbide N3- nitride O2- oxide
F- fluoride

Charges on Common Ions -4 -3 -2 -1 +1 +2 +3

Ionic Compounds Are Neutral
The positive charge must balance the negative charge We could use trial and error to find the least common charge - + - + - + 2.8 The formulas of many ionic compounds can be predicted

Determining The Formula Of An Ionic Compound
Practically, we can often accomplish this by making the charge magnitude (not the charge) of one ion into the subscript for the other. (The “Criss-cross” rule) If you choose this approach, make sure that the subscripts are reduced to the lowest whole number. Al3+ O2- Mg2+ O2- NH4+ PO43- Note that when groups of atoms (polyatomic ions) are used more than once, they are enclosed in parentheses. When used only once, the subscript 1 (and any parentheses) should be omitted. Chem FAQ: How can I predict the formula of an ionic compound given the formulas and charges of its ions? What are the formulas and names of common transition and post-transition metal ions? 2.8 The formulas of many ionic compounds can be predicted

Your Turn! Which of the following is the correct formula for the formula unit composed of potassium and oxygen ions? KO KO2 K2O none of these

Your Turn! Which of the following is the correct formula for the formula unit composed of Fe3+ and sulfide ions? FeS Fe3S2 Fe2S3 none of these

Transition And Post-transition Metals Usually Have Multiple Charges
Chromium Cr2+, Cr Zinc Zn2+ Manganese Mn2+, Mn3+ Silver Ag+ Iron Fe2+, Fe Cadmium Cd2+ Cobalt Co2+, Co Gold Au+, Au3+ Nickel Ni2+ Mercury Hg22+, Hg2+ Copper Cu+, Cu2+ Post-transition Metals Tin Sn2+, Sn4+ Lead Pb2+, Pb4+ Bismuth Bi3+ Note that most of these have variable charges. Hence the name “transition” 2.8 The formulas of many ionic compounds can be predicted

Some Polyatomic Ions (Ions With Two Or More Atoms):
NH4+ Ammonium ion CO32- carbonate ion OH- hydroxide ion H3O+ hydronium ion NO2- nitrite ion SO32- sulfite ion NO3- nitrate ion SO42- sulfate ion ClO2- chlorite ion CrO42- chromate ion ClO3- chlorate ion Cr2O72- dichromate ion PO43- phosphate ion See Table 2.5 for others Note that these have characteristic formulae and also characteristic names. 2.8 The formulas of many ionic compounds can be predicted

The Stock System Of Naming Ionic Compounds
Cations: If the metal forms only one positive ion, the cation name is the English name for the metal If the metal forms more than one positive ion, the cation name is the English name followed, without a space, by the numerical value of the charge written as a Roman numeral in parentheses Anions: monatomic anions are named by adding the “–ide” suffix to the stem name for the element polyatomic ions use the names in Table 2.5 Chem FAQs: How do I name an ionic compound, given its formula? How do I write the formula of an ionic compound, given its name? 2.9 Molecular and ionic comounds are named following a system

a: AlN b: Al3N3 c: Al3N2 d: Al2N3 Question:
What is the chemical formula of the ionic compound formed by aluminum and nitrogen? a: AlN b: Al3N3 c: Al3N2 d: Al2N3

Name the following compounds
K2S NiSO4 CoF3 (NH4)3PO4 MoBr3 Pb(NO2)4

Write the formula: Potassium chloride Calcium oxide Aluminum hydride
Problem Solving Write the formula: Potassium chloride Calcium oxide Aluminum hydride Tin(II) bromide Copper(I) iodide Calcium chlorite

a: NH4P b: NH4PO4 c: (NH4)3P d: (NH4)3PO4 e: NH4(PO4)3
Question: What is the formula of the ionic compound formed by ammonium ion and phosphate ion? a: NH4P b: NH4PO4 c: (NH4)3P d: (NH4)3PO4 e: NH4(PO4)3

a: CuS b: Cu2S c: Cu2SO4 d: CuSO4
Question: What is the formula of copper(II) sulfate? a: CuS b: Cu2S c: Cu2SO4 d: CuSO4 w1tp.com

Question: What is the name of NaC2H3O2 • 3H2O? a: sodium carbonate hydrate b: sodium carbonate trihydrate c: sodium acetate hydrate d: sodium acetate trihydrate e: sodium hydrogen carbonate trihydrate Chemicalforums.com

Chemical Name as Name as Symbol Stem First Element Second Element
In BINARY COUMPOUNDS: first element by English name, the second by appending the suffix –ide to its stem. Greek letter for each indicates number Chemical Name as Name as Symbol Stem First Element Second Element O ox oxygen oxide S sulf sulfur sulfide N nitr nitrogen nitride P phosph- phosphorus phosphide F fluor fluorine fluoride Cl chlor chlorine chloride Br brom bromine bromide I iod iodine iodide Then use prefix…

mono- = 1 (often omitted) hexa- = 6 di- = 2 hepta- = 7
Greek prefixes indicate number of each atom in binary molecular compounds Greek Prefixes mono- = 1 (often omitted) hexa- = 6 di = hepta- = 7 tri = octa = 8 tetra- = nona- = 9 penta- = deca- = 10 Examples: PF = phosphorus pentafluoride HCl = hydrogen chloride N2O5 = dinitrogen tetraoxide Note: many compounds have common names, like water for H2O.

Ban DiHydrogen Oxide http://www.gopetition.com
Dihydrogen monoxide (DHMO) is colorless, odorless, tasteless, and kills uncounted thousands of people every year. Most of these deaths are caused by accidental inhalation of DHMO, but the dangers of dihydrogen monoxide do not end there. Prolonged exposure to its solid form causes severe tissue damage. Symptoms of DHMO ingestion can include excessive sweating and urination, and possibly a bloated feeling, nausea, vomiting and body electrolyte imbalance. For those who have become dependent, DHMO withdrawal means certain death. Dihydrogen monoxide: is also known as hydroxl acid, and is the major component of acid rain contributes to the "greenhouse effect.“ may cause severe burns. contributes to the erosion of our natural landscape. accelerates corrosion and rusting of many metals. may cause electrical failures and decreased effectiveness of automobile brakes. has been found in excised tumors of terminal cancer patients.

Name the following compounds
ClO3 NF3 HI BBr3 N2O5

Question: What is the name of SF4 ? a: sulfur fluoride b: monosulfur tetrafluoride c: monosulfur tetrafluorine d: sulfur tetrafluoride e: sulfur tetrafluorine genchem.chem.wisc.edu

What is the formula of tetraphosphorus decaoxide? a: PO10 b: P4O2
Question: What is the formula of tetraphosphorus decaoxide? a: PO10 b: P4O2 c: P4O10 d: 4PO10 e: 40 PO

2.9 Molecular and ionic comounds are named following a system

Learning Check: Name The Following
Na2O K2O NH4ClO3 Mg(C2H3O2)2 Cr2O3 ZnBr2 Note that chromium has a variable charge, hence we must specify. Since Zn has only 1 common charge, this is unnecessary. Other transition metals with only one common charge are Cd2+, and Ag+ 2.9 Molecular and ionic comounds are named following a system

Overview: Molecules vs. Formula Units
electrically neutral, discrete particles called molecules Neutral groups of charged particles called formula units FIG Molecular and ionic substances. (a) In water there are discrete molecules that each consist of one atom of oxygen and two atoms of hydrogen. Each particle has the formula H2O. (b) In sodium chloride, ions are packed in the most efficient way. Each Na is surrounded by six Cl, and each Cl is surrounded by six Na. Because individual molecules do not exist, we simply specify the ratio of ions as NaCl.

Summary of Properties Hardness and brittleness
Molecular compounds tend to be soft and easily crushed because the attractions between molecules are weak and molecules can slide past each other Ionic compounds are hard and brittle because of the strong attractions and repulsions between ions

Electrostatic Forces The oppositely charged ions in ionic compounds are attracted to one another by ELECTROSTATIC FORCES. These forces are governed by COULOMB’S LAW.

Melting points To melt the particles in the solid must have sufficient kinetic energy to overcome the attractions between particles Molecular compounds tend to have weak attractions between particles and so tend to have low melting points Many molecular compounds are gases at room temperature Ionic compound tend to have strong attractions so they have high melting points Nearly all ionic compounds are solids at room temperature

Importance of Coulomb’s Law
NaCl, Na+ and Cl-, m.p. 804 oC MgO, Mg2+ and O2- m.p oC

Electrical conductivity requires the movement of electrical charge
Ionic compounds: Do not conduct electricity in the solid state Do conduct electricity in the liquid state The ions are free to move in the liquid state Molecular compounds: Do not conduct electricity in the solid or liquid state Molecules are comprised of uncharged particles

Question: A clear, colorless solid is brittle and conducts electricity when molten but not when solid. Is this solid a sample of an ionic or covalent compound? a: ionic b: molecular c: it’s equally likely to be either ionic or molecular d: it’s impossible to tell without additional information

Question:

Question: CuSO4 • 5H2O

Question:

Question: cavemanchemistry.com

Question:

Question: In general, are the melting points of molecular compounds higher or lower than those of ionic compounds? a: higher b: lower

CHEM115 General Chemistry I

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CHEM115 General Chemistry I

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