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Chapter 2
Atoms, Molecules and Ions
Benchmarks
Use these benchmarks as an overview of what will be in the chapter.
Read a section of the chapter; read through the notes to see a summary of that section.
Complete the example and exercise questions throughout the section.
Complete the practice problems that relate to that section. CHECK YOUR ANSWERS!
DEVELOPMENT OF ATOMIC THEORY

List the scientists involved in the development of the atomic theory. Add their part of the
discovery. Remember the song? (Democritus, Aristotle, Dalton, Thomson, Goldstein,
Rutherford, Chadwick, Bohr, Heisenberg, Schrödinger)
SUBATOMIC PARTICLES

What are the three subatomic particles, where are they within the atom, what is the charge and
mass of each?

How do you determine the number of subatomic particles? For example 31H+

Define isotopes.
PERIODIC TABLE

Who told the elements where to go????

How is the periodic table arranged now?

What are the three types of elements and where are each located on the PT?
NAMING COMPOUNDS

What are the rules for naming the seven different types of compounds? (monatomic, binary
ionic, ternary ionic, binary molecular, acids, hydrocarbons, hydrates)
BALANCING EQUATIONS

How do you balance a chemical equation?
HOMEWORK: LABEL AS CHAPTER 2. WORK THROUGH QUESTIONS 31 – 91 ODDS. SHOW FULL
THOUGHT PROCESS/WORK SHOWN, SO THAT YOU WILL REMEMBER HOW TO DO IT IN THE FUTURE.
CHECK YOUR ANSWERS TO THE ODDS WITH THE BACK OF THE BOOK A-27.
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Chapter 2
Atoms, Molecules and Ions
2.1 ATOMIC THEORY OF MATTER
DALTON’S ATOMIC THEORY (p44) His four-point theory.
1.
All matter is composed of atoms.
2.
All atoms of an element are identical.
3.
Elements can chemically combine to form compounds.
Law of Multiple Proportions: two elements can react to form different compounds.
4.
A chemical reaction occurs when atoms rearrange.
Atomic Symbols: the abbreviation used to represent an element. (p45)
Complete Questions 31-33 odds p.82
2.2 THE STRUCTURE OF THE ATOM (p45)
Electron: negatively charged particle that circles the nucleus, 1/1840amu
-
Found by JJ Thomson using a cathode ray tube. (p47-48)
-
Robert Millikan determined the electric charge of e- through the oil drop experiment. (p48)
Proton: positively charged particle contained in the nucleus, 1amu (p50)
-
1 atomic mass unit (amu) is the mass of 1/12 the mass of a carbon-12 atom, 1.66054*10-27kg.
(p53)
-
the atomic number (Z) is the number of protons.
Neutron: neutrally charged particle contained in the nucleus, 1amu(p50)
-
the mass number (A) is the sum of the protons & neutrons.
Nucleus: the central core of an atom, positively charged & containing most of the mass. (p45)
-
Found by Ernest Rutherford using gold foil experiment (p49)
A nuclide is an atom with specific atomic number (Z) and mass number (A). (p50)
-
A
zSymbol
:
23
11Na
Exercise 2.1 p 51. A nucleus consists of 17p+ and 18no, what is the nuclide symbol?
Complete Questions 35-41 odds p. 83
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Chapter 2
2.3 NUCLEAR STRUCTURE; ISOTOPES
Isotopes: differ in the number of neutrons in the nucleus. (p51)
-
Fractional Abundance: the fraction of the total number of atoms that is composed of a
particular isotope. (p54)
-
Mass Spectrometers: are used to separate the isotopes and determine the abundance of each.
(p53 &54)
2.4 ATOMIC WEIGHTS
Atomic Weight: the average atomic mass for the naturally occurring element, in amu.(p53)
- multiply fractional abundance by mass of isotope, repeat for each isotope and add.
Work through example 2.2 and exercise 2.2 p 54 - 55
Complete Questions 43-47 odds p. 83
2.5 PERIODIC TABLE OF THE ELEMENTS
-
arrangement of elements in columns and rows, highlighting the regular repetition of
properties. (p55)
-
 Who told the elements where to go?  MENDELEEV!
o But he was not totally correct because he used atomic weight instead of atomic
number. (p55)
-
Mosley had the proper alignment
Periods: go across, there are 7 periods (p56)
Groups & Families: go down, there are 18 columns (p56)
-
the A groups are the main-group or representative elements (p57)
-
the B groups are the transition metals.
Metals: are on the left of the PT are lustrous, malleable, ductile & good conductors (p57)
Nonmetals: are on the right in the PT are dull, brittle & insulators. (p57)
Metalloids: are on the staircase and have properties of both metals and nonmetals. (p57)
Exercise 2.3 p 57
Element
Period
Group
3
Chapter 2
Se
Cs
Fe
Cu
Br
Complete Questions 49-53 odds p.83
2.6 CHEMICAL FORMULAS; MOLECULAR AND IONIC SUBSTANCES
A chemical formula is a symbolic representation of a compound. (p58)
A molecule is a compound formed between 2 nonmetals. (p58)
- molecular formula: is the chemical formula of the molecule. (p58)
- structural formula: shows how the atoms are bonded in the MC
-
polymers are large molecules formed from smaller molecules repeatedly linked together.
o monomers are the small molecules.(p60)
Complete Questions 55-61 odds p. 84
IONS
An ion is an atom with a charge. (p61)
-
A cation is a positively charged ion.
-
An anion is a negatively charged ion.
An ionic compound is formed between a cation and an anion.(p61)
-
a formula unit: is the chemical formula of an ionic compound.
Example 2.3 p 62. Write the formula for chromium (III) oxide
Exercise 2.4 p 63. Write the formula for potassium chromate
Complete Questions 63-65 odds p.84
2.7 ORGANIC COMPOUNDS
Organic Compounds are molecular substances containing carbon.(p63)
Hydrocarbons contain only C & H. (p64) Prefix, Root, Suffix
 PREFIX
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Chapter 2
o Meth-, eth-, prop-, but-, pent-, hex-, hept-, oct-, non-, dec ROOT
o ane = single bonds, -ene = double bond, -yne = triple bond
Functional Group is the reactive portion of a molecule that undergoes predictable reactions. (p64)
 SUFFIX
o Alcohol, OH = -ol
o Carboxylic acid, COOH = -oic acid
2.8 NAMING SIMPLE COMPOUNDS
-
The systematic naming of chemical compounds. (p64)
Monatomic Ions
-
metals: name metal + ion, include charge of transition metals
-
nonmetals: change ending to -ide
Polyatomic ions
-
Table 2.6 p67 or ½ sheet from chemistry
-
Must know by memory – not provided on AP test!
Binary Ionic & Ternary Ionic (p68)
-
name the cation and then the anion
-
must include charge of transition metals
Example 2.4 p 68. Name Mg3N2 and CrSO4.
Exercise 2.5 p 69. Name CaO and PbCrO4.
Example 2.5 p 69 Write the formula for iron (II) phosphate and titanium (IV) oxide.
Exercise 2.6 p 69 Write the formula for thallium (III) nitrate.
Binary Molecular (p69)
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Name the first nonmetal, add prefix unless mono
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Name the second nonmetal with its prefix
Example 2.6 p 71 Name N2O4 and P4O6
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Chapter 2
Exercise 2.7 p 71 Name Cl2O6, PCl3 and PCl5.
Example 2.7 p 71 Write the formula for disulfur dichloride and tetraphophorus trisulfide
Exercise 2.8 p 71 Write the formula for carbon disulfide and sulfur trioxide
Acids (p71-72) (oxoacid: H, O & another element)
-
anion ends in –ide  hydro- -ic acid
-
anion ends in –ite  -ous acid
-
anion ends in –ate  -ic acid
Example 2.8 p 72 Write the formula and name for the anion in selenic acid, H2SeO4
Exercise 2.9 p 73 Write the formula and name for the anion in perbromic acid, HBrO4.
Hydrates: compound with H2O bonded to it (p73)
-
name the compound
-
use a prefix to tell the # of H2O + hydrate
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see example 2.9 & 2.10 and be able to do exercises p73-74
Example 2.9 p 73 Name MgSO4*7H2O
Exercise 2.10 p 74 Name Na2CO3*10H2O
Example 2.10 p 74 Write the formula for calcium sulfate dehydrate
Exercise 2.11 p 74 Write the formula for sodium thiosulfate pentahydrate
Complete Questions 67-81 odds p.84 – 85
2.9 AND 2.10 CHEMICAL EQUATIONS
When writing a chemical equation, put the reactants on the left and the products on the right.
Reactants react together to produce products.
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Chapter 2
To balance an equation, select coefficients that will make the numbers of atoms of each element equal
on both sides of the equation. (Law of Conservation of Mass)
-
First, balance the atoms for elements that occur in only one substance on each side of the
equation.
-
Balance H and O last
-
Remember the diatomics (H2, N2, O2, F2, Cl2, Br2, I2)
-
If everything balances except for one compound, multiply the 1st coefficient by two and
rebalance.
Example 2.11 p 77 Balance
H3PO3  H3PO4 + H2
Ca + H2O  Ca(OH)2 + H2
Fe2(SO4)3 + NH3 + H2O  Fe(OH)3 + ( NH4)2SO4
Exercise 2.12 p 78 Balance
O2 + PCl3  POCl3
P4 + N2O  P4O6 + N2
As2S3 + O2  As2O3 + SO2
Ca3(PO4)2 + H3PO4  Ca(H2PO4)2
Complete Questions 83-91odds p85-86
Be sure to read through the “A Chemist Looks At” segments for sodium and chlorine at the end of the
chapter. The information in these profiles is considered common knowledge on the AP Test!
Extra Assignment: Complete cumulative-skills problems 123, 125, 127.
detail, must be shown to receive extra points.
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All work, explained in