Ch. 1: Introduction to Chemistry

Standards: INQB; Matter consists of atoms that have internal structures that dictate their chemical and physical behavior.

Targets:• What is Chemistry?• Branches of Chemistry• Areas Involving Chemistry• Careers in Chemistry• Scientific Method

What is Chemistry?

Chemistry is the study of the composition of matter and the changes that matter undergoes.

• What is matter?– Anything that takes up space and has mass

• What is change?– Make into a different form

Branches of Chemistry

• Inorganic chemistry: Studies matter that does not contain carbon

• Organic chemistry: Studies carbon-containing substances

• Analytical chemistry: Concerned with the composition of substances

• Physical chemistry: Explains and measures the behavior of substances

• Biochemistry: The chemistry of living organisms

Areas of Our Society Involving Chemistry

– Energy: Fuels, insulation, lighting, batteries, nuclear

– Medicine and Biotechnology: Pharmaceuticals, materials, genetics, cloning

– Agriculture: Fertilizer, pesticide, herbicides, fungicides, new crops hormones

– Environment: Waste reduction/treatment/disposal, chemical management, monitoring

– Astronomy/Space Exploration: Rocket fuels, compositions of moon, stars, and planets

– Materials: Metal alloys, plastics, coatings, semiconductors

Careers in Chemistry• Chemist: Analytical chemist, forensic chemist, solid state chemist,

organic chemist, biochemist, electrochemist, quality control

• Chemical Engineer: Process engineer, instrumentation and control engineer, project engineer

• Materials Scientist: Metallurgist, polymer science, corrosion engineer

• Environmental Engineer: Ecologist, compliance, enforcement, waste management, pollution abatement, remediation, HazMat response, wastewater treatment

• Engineering: Mechanical, Civil, Ceramics, Nuclear

• Medical: Physician, nurse, lab technician, oncologist, veterinarian, research

• Pharmacist: Retail, sales, research

Careers in Chemistry (cont.)

• Climatologist: Atmospheric scientist, computer modeling

• Oceanographer: Physical, chemical, geological, biological

• Solar Engineer: Photovoltaic cells, energy storage

• Commercial Diver: Underwater construction, welding, demolition, exploration

• Laser Technician: Medical laser specialist, industrial laser technician,

• Archeologist: Radioisotope dating, material identification

• Health Inspector: FDA, USDA, public health

• Microbiologist: Public health, medical, food, brewmaster, vintner

• Gemologist: Jewelers, insurance, mining

• Firefighter: Hazardous material response, emergency medical technician

Scientific Method

Steps of the Scientific Method:

1.Observation: Use your senses to obtain information directly.

2.Problem: Propose a question based on your observations

3.Hypothesis: Propose an explanation of your problem (If…, then… statement)

4.Experiment: Test your hypothesis.

5.Results: collection of experiment’s data and analysis of data

6.Conclusion: statements about what your experiment found

Scientific Method

Important Terms:o Theory: A broad and extensively tested

explanation of why experiments give certain results.oEx: Atomic Theory: how the atom is structured

o Scientific Law: A concise statement that summarizes the results of many observations and experiments. A scientific law describes a natural phenomenon without attempting to explain it.oEx: Newton’s Laws of Motion

Types of Observations

Quantitative•Must have numbers involved•Usually a measurement using metric units

Qualitative•Using senses: color, smell, texture•NEVER TASTE

Accuracy and Precision

• Accuracy: the measure of how close a measurement is to the actual or true value

• Precision: the measure of how close a series of measurements are to one another

Accuracy and Precision

Low accuracy , Low precision

Low accuracy,High precision

High accuracy,Low precision

High accuracy,High precision

Extensionengine.com

Calculating Error

• Error: the difference between the accepted value and the experimental value– Accepted value: the correct value based on

reliable resources– Experimental value: value measured in the lab

Error = experimental value - accepted value

Calculating Percent Error

• Percent Error: the relative error, shows the magnitude of the error

Percent Error = I error I x 100

accepted value

Measurement in Chemistry• Use the International System of Units (SI)

– Aka: the metric system

Quantity Unit Symbol

Length meter m

Volume Liter L

Mass gram g

Temperature Degree Celsius oC

Density Grams per cubiccentimeter orGrams per mililiter

g/cm3 g/mL

Measurement in Chemistry

Devices to use for taking measurements:– Balance – mass, usually in grams– Ruler – length, usually in cm or mm– Thermometer: temperature, usually in oC– Graduated cylinder: volume, usually in mL

Measurement in ChemistrySignificant Figures (Sig Figs)

In science, a measured quantity has two meanings: The numerical value (with the proper units) The sensitivity (uncertainty) of the measuring

instrument: precision

The number of sig figs is important in calculations

Rules for Sig FigsRules for Counting Sig Figs

1. Every nonzero digit represented in a measurement is significant.24.7 m has 3 sig figs0.4587 has 4 sig figs134.798 has ? sig figs0.6668 has ? sig figs

Rules for Sig Figs

2. Zeros appearing between non zero digits are significant.7003 has 4 sig figs0. 96501 has 5 sig figs40.30609 has ? sig figs0.306201 has ? sig figs

Rules for Sig Figs

3. Zeros ending a number to the right of the decimal point are significant23.80 has 4 sig figs0.130700 has 6 sig figs1,006.00 has ? sig figs0.34090 has ? sig figs

Rules for Sig Figs4. Zeros starting a number or ending

the number to the left of the decimal point are not counted as significant16000 has 2 sig figs0.0002709 has 4 sig figs870,600 has ? sig figs0.0450 has ? sig figs

Rules for Sig FigsGeneral Rule for Counting Sig Figs

Start on the left with the first nonzero digit.

End with the last nonzero digit OR with the last zero that ends the number to the right of the decimal point

Sig Fig PracticeIndicate the number of sig figs in the numbers:

1.5.678 m

2.0.0135 g

3.100.050 g

4.10.050 g

5.400.00 m

Rules for Sig Fig Calcuations

Sig Figs in Calculations: Addition & Subtraction

• The answer to an addition or subtraction calculation must be rounded to the same number of decimal places as the measurement with the least number of decimal places.

Rules for Sig Fig Calculations

12.52 m + 349.0 m + 8.24 m = 369.76 m

12.52 has 2 decimal places; 349.0 has 1 decimal place; 8.24 has 2 decimal

placesThe answer is rounded off to 1 decimal

place = 369.8 m

Rules for Sig Fig Calculations

Sig Figs in Calculations: Multiplication & Division

The answer to a multiplication or division calculation must be rounded to the same number of significant figures as the measurement with the least number of significant figures.

Sig Fig Practice

Metrics

Density

• The ratio of the mass of an object to its volume

• Density = Mass Volume