Welcome to the World of Chemistry Mrs. Panzarella Rm. 351

Chemistry Biology Plant Sciences Geology Environmental Science Health and MedicineNuclear Chemistry Physics Astronomy Biochemistry Biology “The Central Science”

Branches of Chemistry Many major areas of study for specializationMany major areas of study for specialization Several career opportunitiesSeveral career opportunities Also used in many other jobsAlso used in many other jobs

1. Organic Chemistry Organic is the study of matter that contains carbon Organic chemists study the structure, function, synthesis, and identity of carbon compounds Useful in petroleum industry, pharmaceuticals, polymers

2. Inorganic Chemistry Inorganic is the study of matter that does NOT contain carbon Inorganic chemists study the structure, function, synthesis, and identity of non- carbon compounds Polymers, Metallurgy

3. Biochemistry Biochemistry is the study of chemistry in living thingsBiochemistry is the study of chemistry in living things Cross between biology and chemistryCross between biology and chemistry Pharmaceuticals and geneticsPharmaceuticals and genetics

4. Physical Chemistry Physical chemistry is the physics of chemistry… the forces of matterPhysical chemistry is the physics of chemistry… the forces of matter Much of p-chem is computationalMuch of p-chem is computational Develop theoretical ideas for new compoundsDevelop theoretical ideas for new compounds

5. Analytical Chemistry Analytical chemistry is the study of high precision measurementAnalytical chemistry is the study of high precision measurement Find composition and identity of chemicalsFind composition and identity of chemicals Forensics, quality control, medical testsForensics, quality control, medical tests

The Language of Chemistry The elements, their names, and symbols are given on the PERIODIC TABLE (along with reference Table S)The elements, their names, and symbols are given on the PERIODIC TABLE (along with reference Table S) Dmitri Mendeleev ( )

Chemical Symbols Each element on the periodic table is represented by a chemical symbol

Chemical Symbols (continued) NOTICE!! The Chemical symbols with two letters are written with a capital first letter and lowercase second letter

ELEMENTS TO KNOW Atomic numbers: 1-38, 47, 50-56, 74, 78-80, 82-84, 86, 92, 94 X A Z Mass Number Atomic Number Element Symbol LEARN the name and chemical symbol spelling counts-use Table S or Agenda (pg R-7) Complete pages 2-3 in Learning Guide Quiz Thursday

Chemistry The study of matter, energy and their interactions

Measurement 1) N 3 : No Naked Numbers. All measurements and answers to math problems must have units written after the numbers. 2) No Work, No Credit. You must show the math set-up when doing math problems.

Measurement Qualitative observation –Focus on the qualities of an object. –Ex. Color of an object Quantitative observation –Characteristics of an object that can be measured. –Ex. Mass, Length

Accuracy vs. Precision Accuracy - how close a measurement is to the accepted value Precision - how close a series of measurements are to each other ACCURATE = CORRECT PRECISE = CONSISTENT

Three targets with three arrows each to shoot. Can you hit the bull's-eye? Both accurate and precise Precise but not accurate Neither accurate nor precise How do they compare?

Figure 1.16 precise and accurate precise but not accurate Precision and accuracy in the laboratory.

Significant Figures Indicate precision of a measurement. Indicate precision of a measurement. Includes all digits that can be known precisely plus a last digit that must be estimated 2.35 cm

The number of significant figures in a measurement depends upon the measuring device. Figure o C32.33 o C

Rules for Significant Figures a. All non-zero digits are significant b. Zeroes between non-zero digits are significant c. In measurements containing an expressed decimal, zeros to the right of NON-ZERO digits are significant.

Pacific = Decimal Present Atlantic = Decimal Absent Count from the ocean towards the coast starting with the first nonzero digit, and include all the digits that follow Atlantic/Pacific Rule

, Significant Figures Counting Sig Fig Examples , sig figs 3 sig figs 2 sig figs

Significant Numbers in Calculations An answer cannot be more precise than the least precise measurement

Adding and Subtracting The answer has the same number of decimal places as the measurement with the fewest decimal places one decimal place two decimal places answer 26.5 one decimal place

Learning Check In each calculation, round the answer to the correct number of significant figures. A = 1) ) ) 257 B = 1) ) ) 40.7

Round to the calculated answer until you have the same number of significant figures as the least precise measurement. (13.91g/cm 3 )(23.3cm 3 ) = g 324 g 4 SF 3 SF Multiplying and Dividing

Learning Check A X 4.2 = 1) 9 2) 9.2 3) B ÷ 0.07 = 1) ) 62 3) 60

Percent Error Indicates accuracy of a measurement Formula on Reference Table T your value accepted value

Percent Error A student determines the density of a substance to be 1.40 g/mL. Find the % error if the accepted value of the density is 1.36 g/mL. % error = 2.9 %

DENSITY Mercury 13.6 g/cm 3 an important and useful physical property standard values can be found on Table S Density usually decreases as temperature increases because volume increases making the mass more spread out, but the total mass stays the same. One exception!! WATER Density decreases as the temperature decreases in water

Density example An object has a volume of 825 cm 3 and a density of 13.6 g/cm 3. Find its mass. GIVEN: V = 825 cm 3 D = 13.6 g/cm 3 M = ? WORK : M = DV M = (13.6 g/cm 3 )(825cm 3 ) M = 11,200 g

Metric System 1. length –The meter is the basic unit of length. The meter stick is divided into 100 equal parts each 1 cm in length »1km = 10 3 micro meter – m 2. Mass –The kilogram is the basic unit of mass –1kg is equal to the mass of 1L of water at 4 C therefore 1g of water equal to the volume of 1cm 3 (ml) at 4 C 3. Volume –The space occupied by matter. Derived from measurement of length. –1L = 1000cm 3 1ml = 1cm 3

Common Decimal Prefixes Used with SI Units Table 1.3 Based on powers of 10

SI Prefix Conversions (based on powers of 10) deci-d10 -1 centi-c10 -2 milli-m10 -3 Prefix SymbolFactor micro-  nano-n10 -9 pico-p Kilo- k10 3 BASE UNIT Hecto- h10 2 Deka-da 10 1 move left move right

The “Unit fraction” Method aka Dimensional Analysis Steps: 1. Identify starting & ending units. 2. Line up conversion factors so units cancel. 3. Multiply all top numbers & divide by each bottom number. 4. Check units & answer.

set up: known value with unit x unknown unit known unit Ex. 1 A rattlesnake is 2.44 m long. How long is the snake in cm? 2.44 m x ______cm = cm m

Solution : A rattlesnake is 2.44 m long. How long is the snake in cm? 2.44 m x 100 cm = 244 cm 1 m

Write and solve for the following problems using the factor label method: 1) 20 cm to m 2) 500 ml to L 3) L to mL 4) 45 m to km 5) 805 dm to km 6) 81 cm to mm 7) 5.29 cs to s 8) 3.78 kg to g

Scientific Notation Scientific notation is a way of expressing really big numbers or really small numbers.Scientific notation is a way of expressing really big numbers or really small numbers. 65,000 kg  6.5 × 10 4 kg Move decimal until there’s 1 digit to its left. Places moved = exponent. Large # (>1)  positive exponent Small # (<1)  negative exponent

Graphs should contain the following features: Independent variable in the X axis (with units) Dependent variable on the Y axis (with units). uniform numerical scale Include a title: (Dependent Variable) vs. (Independent Variable) Data points, circled with “point protectors”. Data points connected with a line or a best fit line Done on graph paper in pencil or on the computer