Important things to remember in chemistry

MEMORIZE the starred pages

Introduction and Measurement

Chemistry is

• • • • the study of matter and the changes it undergoes (transformations) the study of reactions and interactions among different types of matter the study of connections between macroscopic and submicroscopic events the science that seeks to understand the behavior of matter by studying the behavior of atoms and molecules

Memorize for week 1

3

Memorize for week 1

International System of Units (SI)

4

Memorize for week 2

5

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A Comparison of Temperature Scales

K = 0 C + 273.15

273 K = 0 0 C 373 K = 100 0 C 0 5 9 0 F – 32) 0 9 5 0 C + 32 32 0 F = 0 0 C 212 0 F = 100 0 C 7

Significant Figures

• Any digit that is not zero is significant 1.234 kg 4 significant figures • Zeros between nonzero digits are significant 606 m 3 significant figures • Zeros to the left of the first nonzero digit are

not

significant 0.08 L 1 significant figure • If a number is greater than 1, then all zeros to the right of the decimal point are significant 2.0 mg 2 significant figures • If a number is less than 1, then only the zeros that are at the end and in the middle of the number are significant 0.00420 g 3 significant figures http://www.roch.edu/people/tebrown/pages/sigfig2.htm

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Significant Figures

Exact Numbers Numbers from definitions or numbers of objects are considered to have an infinite number of significant figures The average of three measured lengths; 6.64, 6.68 and 6.70?

6.64 + 6.68 + 6.70

= 6.67333 = 6.67 = 7 3 Because 3 is an

exact number

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CALCULATIONS with Significant Figures

Addition or Subtraction The answer cannot have more digits to the right of the decimal point than any of the original numbers.

89.332

+ 1.1

90.432

one significant figure after decimal point round off to 90.4

3.70

-2.9133

0.7867

two significant figures after decimal point round off to 0.79

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CALCULATIONS with Significant Figures

Multiplication or Division The number of significant figures in the result is set by the original number that has the

smallest

number of significant figures 4.51 x 3.6666 = 16.536366 = 16.5

3 sig figs round to 3 sig figs 6.8 ÷ 112.04 = 0.0606926 = 0.061

2 sig figs round to 2 sig figs 11

Dimensional Analysis Method of Solving Problems 1. Determine which unit conversion factor(s) are needed 2. Carry units through calculation 3. If all units cancel except for the

desired unit(s)

, then the problem was solved correctly.

given quantity x conversion factor = desired quantity given unit x desired unit = desired unit given unit 12

A

law

is a concise statement of a relationship between phenomena that is always observed and measured to be the same under the same conditions.

Ex. Law of Acceleration

Force = mass x acceleration A natural law compactly summarizes patterns in a large amount of data that often apply only under special conditions and are descriptions of nature, not facts or explanations

Ex. Law of Gravity – “

What goes up, must come down

”

Force Gravity = G _________ 2 d A

scientific law

is a statement that summarizes all past observations and predicts future observations

Ex. Law of Conservation of Mass

– “In a chemical reaction, matter is neither created nor destroyed.” CH 4 + 2 O 2 --> CO 2 + 2 H 2 O A

law

allows you to predict future observations 13

Atoms, Molecules and Ions Elements and compounds: names and formula writing

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

• • •

Our definitions

Atom : smallest, independent, uncharged, unique unit of matter ex. An atom of hydrogen, H

H

Molecule : two or more atoms bonded together chemically; electrically neutral ex. A molecule of hydrogen gas H 2

H-H

Ion : an atom that has acquired a charge, either positive (+), called cation or negative (-), called anion ex. Hydrogen ion

H +

• Polyatomic ion : a group of atoms bonded to each other but carrying an over-all charge, either positive (+) or negative (-) ex. Hydroxide anion, OH

O-H -

These terms are used to describe matter on the basis of the particles they are made up of 15

• • • • • • •

Orbital: The pathway of an electron

It is the region in space where the probability electron is greatest of finding an Every set of orbitals is also known as an energy level ; It is related to the period (horizontal row) in the periodic table and represents the relative distance from the nucleus An orbital can contain a maximum of 2 electrons per individual orbital Electrons have a specific amount of energy and can give off or absorb energy as they enter or leave an orbital The basic shape is a sphere but becomes more complex as more space is available father from the nucleus An orbital is not physical material but is defined by the presence of an electron http://winter.group.shef.ac.uk/orbitron/AOs/1s/index.html

Types of compounds and how they are named

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Memorize for week 3

Memorize these names of common negative ions and their charges 18

Memorize these Common Polyatomic Ions and their charges

Memorize for week 3 Name

acetate carbonate hydrogen carbonate (aka bicarbonate) hydroxide nitrate nitrite chromate dichromate ammonium

Formula

C 2 H 3 O 2 – CO 3 2– HCO 3 – OH – NO 3 – NO 2 – CrO 4 2– Cr 2 O 7 2– NH 4 + Tro, Chemistry: A Molecular Approach 19

Name

hypochlorite chlorite chlorate perchlorate sulfate sulfite hydrogen sulfate (aka bisulfate) hydrogen sulfite (aka bisulfite)

Formula

ClO – ClO 2 – ClO 3 – ClO 4 – SO 4 2– SO 3 2– HSO 4 – HSO 3 –

Periodic Pattern of Polyatomic Ions

-ate groups

3A

BO 3 -3

4A

CO 3 -2

SiO 3 -2 5A

NO 3 -1 PO 4 -3

AsO 4 -3 6A

SO 4 -2

SeO 4 -2 TeO 4 -2 7A

ClO 3 -1

BrO 3 -1 IO 3 -1 Tro, Chemistry: A Molecular Approach 20

Memorize for week 3

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Memorize for week 3

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Memorize for week 3

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Naming = Nomenclature

All Compounds

metal nonmetal nonmetal nonmetal has H @ start or H that can be donated