SummaryChapter 1 - 4

Chemistry: The Molecular Nature of Matter, 6th editionBy 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

Unit Conversions

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

NA = 6.022 x 1023 particles/mole

Time conversions: dhrms

1 mL = 1 cm3

T(kelvin) = T(°C) + 273.15°F = 1.8°C +32

Equations

Density = mass / Volumed = m/V

dH2O = 1 g/mL = 1 g/cm3

Molecular Mass (MM) = Molecular Weight (MW)=

mass/molesMM = m/n

MMmolecule = Σ MMatoms in molecules

Equations & Conversions to Memorize

Elements & Molecules

X = Element symbol (ie O = oxygen)A = Isotope Mass Number = # protons + # neutronsZ = Atomic Number = # protons

6

C12.01

atomic number

element symbol

atomic weight (amu) = weighted average of atomic weight of isotopes

Elements on the Periodic

Table

H C H

H

H

Drawing Molecules:

Methane CH4

Emperical Formula: AxBy Ex: CH3O

Molecular Formula: An × xBn × y Ex: C2H6O2

Structural Formula: AwAxBz Ex:

HOCH2CH2OH

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

Chemical Equations

2C4H10 + 13O2 8CO2 + 10H2O

2 molecules of C4H10 13 molecules of O2

10 molecules of C4H108 molecules of

CO2

Balancing Chemical Equations:Unbalanced equation:

C4H10 + O2 CO2 + H2O

Balanced equation:

Significant Figure RulesScientific 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:

7. If digit to be dropped is greater than 5, last remaining digit is rounded up.

8. If number to be dropped is less than 5, last remaining digit stays the same.

9. 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:

10. Multiplication/Division: the number of significant figures in answer = number of significant figures in least precise measurement

11. Addition/Subtraction: the answer has same number of decimal places as quantity with fewest number of decimal places.

Molecules: Ionic Compounds

IonsTransfer of one or more electrons from one atom to another Form electrically charged particles

Ionic compound Compound composed of ionsFormed from metal and nonmetal

PropertiesConducts electricity in liquid state when ions are free to

move, but not as a solid

Nomenclature: Cation (charge) Anion-ideie: Iron (II) Oxide = FeO

Fe2+ O2-

Sodium Chloride = NaClNa+ 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.

Al2O3Al3+ O2–

Molecules: Ionic Compounds

Molecules: Covalent Compounds

Molecules 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

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

Nonmetal hydrides Molecule containing nonmetal +

hydrogen Number of hydrogens that combine

with nonmetal = number of spaces from nonmetal to noble gas in periodic table

Naming Binary Molecular Compounds– 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 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

Mole Ratios

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

Stoichiometry

aA + bB cC + dDmass A mass B mass C mass D

moles A moles B moles C moles Da:b b:c c:d

a:c

a:d

x ÷ MM

x ÷ MM

x ÷ MM

x ÷ MM

Limiting Reactant:• Least # moles after equalize with mole

ratio• Use limiting reactant to determine

amount of product

Stoichiometry