Summary
Chapter 1 - 4
Chemistry: The Molecular Nature of Matter, 6th edition
By Jesperson, Brady, & Hyslop
CH 1-4 Concepts to be Familiar With
 Classification of matter: pure substances & mixtures
 Distinguish the difference between chemical and physical properties &
changes
 Atomic Theory
 Laws of Definite Proportions & Conservation of Mass
 Intensive vs extensive properties
 Uncertainty in measurements & communicating that uncertainty with
significant figures
 Accuracy & Precision
 Conversions between units (ie, dimensional analysis)
 Structure of an atom: protons, neutrons, electrons
 Navigate the periodic table: properties shared within a group, trends,
metals/metalloids/nonmetals
 Stoichiometric ratios within atoms and between different molecules
 Difference between empirical, molecular, and structural formulas
Equations & Conversions to Memorize
Unit Conversions
Equations
For metric units (m, kg, s, K, mole):
mega (M) 106
kilo (k) 103
centi (c) 10-2
milli (m) 10-3
micro (μ) 10-6
nano (n) 10-9
Pico (p) 10-12
Density = mass / Volume
d = m/V
dH2O = 1 g/mL = 1 g/cm3
NA = 6.022 x 1023 particles/mole
Time conversions: dhrms
1 mL = 1 cm3
T(kelvin) = T(°C) + 273.15
°F = 1.8°C +32
Molecular Mass (MM) =
Molecular Weight (MW)=
mass/moles
MM = m/n
MMmolecule = Σ MMatoms in molecules
Elements & Molecules
A
Z
X
Elements on
the Periodic
Table
X = Element symbol (ie O = oxygen)
A = Isotope Mass Number = # protons + # neutrons
Z = Atomic Number = # protons
atomic number
6
C
element symbol
12.01
atomic weight (amu) = weighted
average of atomic weight of isotopes
Emperical Formula: AxBy
Ex: CH3O
Molecular Formula: An × xBn × y Ex: C2H6O2
Structural Formula: AwAxBz
Ex: HOCH2CH2OH
Drawing Molecules:
Methane
H
H
C
H
H
Chemical Equations
aA (physical state) + bB (state)  cC (state) + dD (state)
(physical state) = solid (s), liquid (l), gas (g), aqueous (aq)
A, B = reactants
C, D = reactants
a, b, c, d = coefficients to indicate molar ratios of reactants and products
Balancing Chemical Equations:
Unbalanced equation:
C4H10 + O2  CO2 + H2O
Balanced equation:
2C4H10 + 13O2  8CO2 + 10H2O
2 molecules of
C4H10
13 molecules of O2
8 molecules of
CO2
10 molecules of
C4H10
Significant Figure Rules
Scientific convention: All digits in measurement up to and
including first estimated digit are significant.
1. All non-zero numbers are significant.
2. Zeros between non-zero numbers are significant.
3. Trailing zeros always count as significant if number has decimal point
4. Final zeros on number without decimal point are NOT significant
5. Final zeros to right of decimal point are significant
6. Leading zeros, to left of first nonzero digit, are never counted as significant
Rounding Guidelines:
1.
If digit to be dropped is greater than 5, last remaining digit is rounded up.
2.
If number to be dropped is less than 5, last remaining digit stays the same.
3.
If number to be dropped is exactly 5, then if digit to left of 5 is
a. Even, it remains the same.
b. Odd, it rounds up.
Multiplication/Division & Addition/Subtraction:
1. Multiplication/Division: the number of significant figures in answer = number of
significant figures in least precise measurement
2. Addition/Subtraction: the answer has same number of decimal places as
quantity with fewest number of decimal places.
Molecules: Ionic Compounds
Ions
Transfer of one or more
electrons from one atom to
another
Form electrically charged
particles
Ionic compound
Compound composed of ions
Formed from metal and
nonmetal
Properties
Conducts electricity in liquid
state when ions are free to move,
but not as a solid
Nomenclature:
Cation (charge) Anion-ide
ie: Iron (II) Oxide = FeO
Fe2+ O2Sodium Chloride = NaCl
Na+ Cl-
“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.
Al3+ O2–
Al2O3
Molecules: Ionic Compounds
Molecules: Covalent Compounds
Molecules
Nonmetal hydrides
 Molecule containing nonmetal +
hydrogen
 Number of hydrogens that combine
with nonmetal = number of spaces
from nonmetal to noble gas in periodic
table
 Electrically neutral particle
 Consists of two or more atoms
 Covalent compounds have
nonmetal-nonmetal bonds
Chemical bonds
 Attractions that hold atoms
together in molecules
 Arise from sharing electrons
between two atoms
Naming Binary Molecular
Compounds
 Group of atoms that make up
molecule behave as single particle
Molecular formulas
 Describe composition of molecule
 Specify number of each type of
atom present
– First element in formula
•
Use English name
– Second element
 Use stem and append suffix –ide
 Use Greek number prefixes to
specify how many atoms of each
element
Nomenclature Overview for Reference
Mole Ratios
Mole Ratios Within Molecules:
AxBy
Mole ratio of A:B = x:y
Mole Ratios Between Molecules:
aA + bB  cC + dD
Mole ratio of A:B:C:D
= a:b:c:d
Percent Composition & Empirical Formulas
Percent Composition (experimental or theoretical):
Calculate percentage by mass of each element in sample
(mass element) / (total mass of sample) x 100%
Empirical Formula
Simplest ratio of atoms of each element in compound
Obtained from experimental analysis of compound
• If empirical formula is AxBy
• Molecular formula will be An × xBn × y
Molecular Formula
Need molecular mass and empirical formula
Calculate ratio of molecular mass to mass predicted by empirical
formula and round to nearest integer
n=
molecular mass
empirical formula mass
Stoichiometry
aA +
bB
mass A
x÷
MM
moles A

mass B
+
mass C
x÷
MM
a:b
cC
mass D
x÷
MM
moles B
b:c
moles C
dD
x÷
MM
c:d
moles D
a:c
a:d
Limiting Reactant:
• Least # moles after equalize with mole
ratio
• Use limiting reactant to determine
amount of product
æ actual yield ö
÷÷ ´ 100%
percentage yield = çç
è theoretical yield ø
Stoichiometry