Introduction to Chemistry CHEM 1405 Section P02

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Introduction to ChemistryCHEM 1405Section P02

• Dr. John Stankus
• jstankus_at_ccccd.edu
• Week 1 presentations

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Syllabus

• Dr. John Stankus
• Office Hours Thursday 1-2 p.m. in Math Lab
• Additional office hours by appointment
• Contact
• Email jstankus_at_ccccd.edu
• Voice mail 972-578-5550 x 8155

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Grading

• Lecture
• Exams - 5 equal weighted tests (100 pts each)
• Exam 1
• Exam 2
• Exam 3
• Exam 4
• Comprehensive final -
• Quizzes (10 pts each)
• Recitation Grade
• Homework
• Attendance/Participation

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Course Grade

• Lecture Grade 70 of final course grade
• Recitation Grade 10 of final course grade
• Laboratory Grade 20 of final course grade
• Please tell me the laboratory section you are
  registered in if you are not in my laboratory
  section (meets immediately before this)

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Introduction to Chemistry, Classification of
Matter, Measurements

• 1. How do scientists obtain new scientific
  knowledge? Do views or concepts in science
  change?
• 2. What is chemistry?
• 3. How does mass differ from weight?
• 4. How do physical properties of matter differ
  from chemical properties?
• 5. What is the difference between a mixture and a
  compound?
• 6. What is energy? What is potential energy? What
  is kinetic energy?

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How science worksThe Scientific method (1.3)
Observations and Experiments
Find Patterns, and Trends
Formulate and Test Hypothesis
Theory
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Observations and Experiments
Observations and Experiments

• Identify all possible variables
• Control the experimental conditions
• Methodically change one of the variables
• Observe the results
• Record the experimental conditions
• Record the variables values
• Record all results seen

A variable is a data item that changes over the
course of an experiment
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Hypothesis
Find Patterns, and Trends
Formulate and Test Hypothesis

• Examine the data collected
• Find patterns in results
• Often with statistical analysis
• From patterns propose a testable hypotheses

A hypothesis is a tentative explanation of a set
of observations. Hypotheses are tested by
experiment
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Scientific Theory
Observations and Experiments
Find Patterns, and Trends
Formulate and Test Hypothesis
Theory
A theory provides explanations of observed
phenomena by predictions that can be tested
experimentally.
A good scientist will generate as many questions
as he or she answers
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Scientific Law

• A scientific law is a concise verbal statement or
  a mathematical equation that summarizes a broad
  variety of observations and experiences.

Example Boyles Law states that for a given
amount of gas at a constant temperature, the
volume of the gas varies inversely with its
pressure. V1P1V2P2
Einsteins Theory of Relativity E mc2
Ideal Gas Law PV nRT
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Scientific Method Example

• A researcher may observe that a large number of
  insects all have three pairs of legs including
  flies, beetles, grasshoppers and wasps.
• A conclusion may be drawn that all insects have
  three pairs of legs.

Observations and Experiments
Find Patterns, and Trends
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Scientific Method Example (continued)

• Then after evaluating additional insects
  including cockroaches, crickets, moths and bees
• A hypothesis might be formed that all insects
  have three pairs of legs.

Observations and Experiments
Find Patterns, and Trends
Formulate and Test Hypothesis
However, a good scientist would not stop there.
New hypotheses should be formed to further test
the initial observation
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Scientific Method Example (continued)

• Perhaps immature moths should be considered, as
  they are insects too, so they should have three
  pairs of legs.
• However, findings would determine that
  caterpillars or immature moths do not have three
  pairs of legs.
• Then the generalization becomes reformulated into
  all adult insects have three pairs of legs.

Test Hypothesis
Observations and Experiments
Re-Formulate and Test Hypothesis
Theory
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What is chemistry(1.4)

• Chemistry is a study of the composition,
  structure, and properties of matter and of the
  changes that matter undergoes.
• Matter is the physical material of the universe
• Matter is anything that has mass and occupies
  space

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Atoms (1.4)

• Atoms are the smallest unit of matter that we
  associate with chemical behavior
• An Element is composed of a single type of atom
• Examples
• Gold Au
• Hydrogen H
• Lead Pb

An atom is the smallest characteristic particle
of an element.
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Chemical Symbols
Chemical compounds are made up of atoms Symbols
are a shorthand representation of the elements

• Aluminum ? Al
• Bromine ? Br
• Carbon ? C
• Calcium ? Ca
• Chlorine ? Cl
• Copper ? Cu
• (from Latin Cuprum)
• Fluorine ? F

• Iron ? Fe
• (from Latin Ferrum)
• Hydrogen ? H
• Helium ? He
• Oxygen ? O
• Potassium ? K
• (from Latin Kalium)
• Sodium ? Na
• (from Latin Natrium)

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Chemical Symbols

• The symbols for the elements are 1 or 2 letters
• The first letter is always capitalized
• The second Letter is always lower case
• Hf is Hafnium HF is Hydrogen Fluoride

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Elements
Currently Around 112 known elements
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Classification of matter
ALL MATTER
Mixtures
Substances
Mixtures can be separated by physical means
compounds
elements
Composed of a single type of atom
Composed of atoms of two or more elements, in
fixed ratios
homogeneous
heterogeneous
Varies in composition and properties throughout
mixture
Uniform in composition and properties throughout
mixture
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Examples of Compounds
Water, H2O
Propane, C3H8
Methane, CH4
Ethanol, CH3CH2OH
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Examples of Classification of Matter

• Air
• Water
• Tap Water
• Iodized Salt
• Vegetable Soup

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Mass and weight (1.4)

• Mass is the measure of the quantity of matter
  that an object contains
• Weight measures a force

On Moon (1/6 earths gravity)
On Earth
In Space
Weight 180 pounds
Weight-less 30 pounds
Mass 82 kilograms 82
kilograms 82 kilograms
Weight varies with gravity, mass does not
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Physical and Chemical properties

• Physical properties Properties that do not
  change the chemical nature of matter
• are its physical characteristics and behavior
  such as color, odor, or hardness
• Chemical properties Properties that do change
  the chemical nature of matter
• describes how it reacts with other types of
  matter

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Example Physical Properties
Property
Example

• Temperature Water for a bath is at 40 C
• Mass A nickel has a mass of 5 grams.
• Color Sulfur is yellow.
• Odor Hydrogen sulfide stinks.
• Boiling point Water boils at 100 C.
• Solubility Table salt dissolves in water.
• Heat capacity Water has a high heat capacity.
• Hardness Diamond is exceptionally hard.
• Electrical conductance Copper conducts
  electricity.
• Density Water has a density of 1.00 grams
  per milliliter

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Example Chemical Properties
Substance
Typical Chemical Property

• Iron Will rust (combine with oxygen to
  form iron oxide)
• Carbon Will undergo combustion (will combine
  with oxygen to form carbon dioxide)
• Silver Will tarnish (combine with sulfur to
  form silver sulfide)
• Sodium Will react violently with water to form
  hydrogen gas and a solution of sodium
  hydroxide
• Nitroglycerin Will explode (decompose, when
  detonated, to a mixture of gases)

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Physical Changes

• A physical change is one that does not entail any
  change in chemical composition
• Water freezing to form ice
• Iron melting in a blast furnace

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Chemical Changes

• A chemical change involves a change in chemical
  composition
• Iron Rusting
• Natural gas burning

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States of matter
Water as example
LIQUID
GAS
SOLID
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States of matter
GAS
Water as example
SOLID
LIQUID
Property Rigidity Expansion on Heating Compres
sibility
Ice is solid H2O Rigid Slight Slight
Liquid H2O Flows and Assumes Shape of
Container Slight Slight
Gaseous H2O Fills completely Any
Container Expands infinitely Easily Compressed
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States of Matter
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Energy and Energy Conversion (1.6)

• Potential energy is energy due to position or
  arrangement.
• Kinetic energy is the energy of motion.

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Electric Forces

• Like Charges repel
• Opposite Charges Attract

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CHEM 1405

• Class Meeting 2

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Metric System, Calculations, Conversions, Density

• 7. What is the metric system of measurement? How
  does one convert between metric units and the
  units commonly used in the United States?
• 8. What is the difference between precision and
  accuracy in measurements?
• 9. Why is an understanding of significant
  figures important in chemistry? How do we
  determine the number of significant figures to
  report?
• 10. What is density?
• 11. What is the difference between temperature
  and heat?
• 12. How are the different temperature scales
  related to one another?

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Modern Metric System

• International System of Units (SI)
• SI comes from French Systeme International
• Based on decimal system
• All units related by factors of 10
• Prefixes denote magnitude
• All measured quantities based on 7 base units

Makes is easier to use!
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The Seven SI Base Units
Name of Unit
Symbol of Unit
Physical Quantity
meter
Length
m
Mass
kilogram
kg
Time
second
s
Temperature
kelvin
K
Amount of substance
mole
mol
Electric Current
ampere
A
Luminous Intensity
candela
cd
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2.2. Precision and Accuracy
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2.3. Sampling Errors
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2.4. Significant Figures

• 2.4.1. Multiplication and Division
• 2.4.2. Addition and Subtraction
• 2.4.3.

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2.5. Unit conversions
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2.6. Density
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2.7. Energy - Temperature and Heat

• 2.7.1. Temperature2.7.2. Heat