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. o Ex: 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. o Ex: 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 Ix 100 accepted value

Measurement in Chemistry Use the International System of Units (SI) –Aka: the metric system QuantityUnitSymbol Lengthmeterm VolumeLiterL Massgramg TemperatureDegree Celsius oCoC DensityGrams per cubiccentimeter or Grams per mililiter g/cm 3 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 o C –Graduated cylinder: volume, usually in mL

Measurement in Chemistry Significant 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 Figs Rules for Counting Sig Figs 1.Every nonzero digit represented in a measurement is significant m has 3 sig figs has 4 sig figs has ? sig figs has ? sig figs

Rules for Sig Figs 2.Zeros appearing between non zero digits are significant has 4 sig figs has 5 sig figs has ? sig figs has ? sig figs

Rules for Sig Figs 3.Zeros ending a number to the right of the decimal point are significant has 4 sig figs has 6 sig figs 1, has ? sig figs has ? sig figs

Rules for Sig Figs 4.Zeros starting a number or ending the number to the left of the decimal point are not counted as significant has 2 sig figs has 4 sig figs 870,600 has ? sig figs has ? sig figs

Rules for Sig Figs General 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 Practice Indicate the number of sig figs in the numbers: m g g g 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 m m m = m has 2 decimal places; has 1 decimal place; 8.24 has 2 decimal places The answer is rounded off to 1 decimal place = 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