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Introduction to Chemistry

Delve into the fundamentals of chemistry, exploring matter's composition and changes, with a breakdown of branches like inorganic, organic, and analytical chemistry. Discover the significance of physical and biochemistry, as well as science and technology's relationship, and distinguish between theory and law. Learn about historical figures like Aristotle and modern contributions by scientists such as Antoine Lavoisier. Unveil the secrets of the periodic table and the international system of units for measurement.

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Introduction to Chemistry

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  1. Introduction to Chemistry

  2. Part I Chemistry and Technology

  3. Chemistry The study of: • the composition (make-up) of matter • the changes that matter undergoes

  4. What is matter? • Anything that: • has mass and • occupies space (volume).

  5. Mass vs Weight • Mass: a measure of the amount of matter that an object contains. (SI unit kilogram, kg) • Weight: The force with which the earth pulls on an object. (SI unit Newton, N)

  6. The 5 Branches of Chemistry • Inorganic • Organic • Analytical • Physical • Biochemistry

  7. Inorganic Chemistry • The study of chemicals that can but do not have to contain carbon. • The study of chemicals making up nonliving things

  8. Organic Chemistry • The study of chemicals that contain carbon. • Origin: study of chemicals in living organisms.

  9. Organic or Inorganic ? • Sulfuric Acid H2SO4 • Methane CH4 • Hydrochloric Acid HCl • Ethane C2H6

  10. Analytical Chemistry • Composition of matter. Ex:Mass SpectrometerGas Chromatograph http://besg.group.shef.ac.uk/Facilities/Images/gcms.JPG

  11. Physical Chemistry • The study of : • The mechanism • The rate • The energy transfer that happens when matter undergoes change.

  12. Biochemistry • Study of processes that take place in organisms.

  13. Science • What? • Why? • How? • When?

  14. Science and Technology • Science  Pure • Does not necessarily have an application. • Technology  Applied • Has practical applications in society. • Engineering.

  15. Question: Science or Technology? Studying or forming aspirin in a lab in small scale (small amounts).

  16. Question: Science or Technology? • Producing aspirin tablets so that consumers can use them.

  17. Example: Discovery of Nylon by Wallace Carothers in 1930’s https://www.acs.org/content/acs/en/education/whatischemistry/landmarks/carotherspolymers.html

  18. Microscopic- Macroscopic • Micro –(small) • Microscopic- objects can be seen with a microscope. • Macro-(from afar) • Macroscopic- objects are seen without a microscope.

  19. Every Experiment must have… • Hypothesis- an educated guess based on prior knowledge; can be tested by experimentation • Independent Variable- the one variable being tested, changed, and manipulated by the scientist (There is only ONE Independent Variable per experiment.) *goes on x-axis when graphing • Dependent Variable- the variable that changes in response to the independent variable (usually it is what you are measuring/collecting data on) *goes on y-axis when graphing

  20. Remember that you NEVER prove anything; Your hypothesis is either accepted or rejected!

  21. Control Group- must have one group/trial in the experiment that lacks the independent variable – used for comparison • Experimental Group(s)-the groups/trials that contain the independent variable • Controlled Variables- things that need to stay constant throughout the experiment

  22. Theory vs. Law • Theory – an explanation of a natural phenomenon supported by many observations and experiments over time. Supported by evidence and enables scientist to make accurate predictions. • Law – describes relationships under certain conditions in nature. Does not explain why an event occurs, just describes the relationship.

  23. Theory or Law? • A hypothesis that is supported by experimental results, many times. • It cannot be explained why the relationship exists. • All energy cannot be created or destroyed; it merely changes from one form to another. • When blowing a bubble into the air, a force acts upon it, causing it to fall to the floor. • The event is justified by evidence and an explanation.

  24. Aristotle (Greece, 4th Century BC) Philosopher who believed that: • There are 4 elements: earth, water, air, fire. • Matter is perpetually divisible.

  25. Democritus (Greece, 4th Century BC) • First atomic theory • Atom (indivisible).

  26. Alchemists (~300BC-1650 AD)China, India, Arabia, Europe, Egypt • Aiming to: • Change common metals to gold. • Develop medicines. • Developed lab equipment. • Mystical.

  27. Galileo Galilei (Italy 1564 AD) • Father of the scientificmethod (along with the Englishman Francis Bacon 1500’s).

  28. Antoine Lavoisier (France 1743-1794) • Regarded as the Father of Chemistry. • Designed equipment. • Used observations and measurements. • Discovered nitrogen.

  29. Dmitri Mendeléev (Russia, 1834-1907) • First Periodic Table of elements.

  30. Système Internationale d’Unitès Units • SI Units – International System • Basic Units Length (meter) m Mass (kilogram) kg Time (second) s Volume (liter) L • National Bureau of Standards

  31. Helpful Chart to remember Smaller Bigger deci (d) 1/10 deca (da) 10 centi (c) 1/100 hecto (h) 100 milli (m) 1/1000 kilo (k) 1000 micro (m) 1/1000000 mega (M) 1000000 nano (n) 1/ 1000000000 giga (G) 1000000000

  32. Derived Units • These units are derived by multiplying or dividing the base units. • Examples • Speed – m/s • Area – m2 • Volume – m3, but scientist tend to use the L or mL *1cm3 = 1mL • Density = g/mL (D=m/V)

  33. Accuracy vs. Precision • Accuracy – a description of how close a measurement is to the true value of the quantity measured • Precision – the exactness of a measurement

  34. Accuracy verses Precision

  35. Is it Accurate, Precise, Both or Neither? • Known Density = 3.11 g/mL • Test Results 3.77, 3.81, 3.76, 3.80 • Precise, not accurate • Test Results 3.01, 3.89, 3.50, 5.99 • Neither • Test Results 3.04, 3.20, 3.13, 3.07 • Accurate, not precise • Test Results 3.11, 3.12, 3.12, 3.10 • Both

  36. How do we represent error? • Error is the difference between the actual (or accepted) value and the experimental value • Percent Error Percent Error = Accepted – Experimental x100 Accepted

  37. Example Problem • Working in the laboratory, a student finds the density of a piece of pure aluminum to be 2.85 g/cm3.  The accepted value for the density of aluminum is 2.699 g/cm3.  What is the student's percent error?

  38. Solving Word Problems • Analyze • List knowns and unknowns. • Devise a plan. • Write the math equation to be used. • Calculate • If needed, rearrange the equation to solve for the unknown. • Substitute the knowns with units in the equation and express the answer with units. • Evaluate • Is the answer reasonable?

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