Intro to Chem-Unit 1

Introduction to Chemistry Chemistry The study of:  the composition (make-up) of matter  the changes that matter undergoes The 5 Traditional Branches of Chemistry Inorganic Organic Analytical Physical Biochemistry Inorganic Chemistry  The study of chemicals that do not contain carbon. Organic Chemistry  The study of chemicals that contain carbon.  Origin: study of chemicals in living organisms. Analytical Chemistry  Composition of matter; measurable, identifies compounds/components Example: Mass Spectrometer Gas Chromatograph http://besg.group.shef.ac.uk/Facilities/Images/gcms.JPG Physical Chemistry  The study of :  The mechanism  The rate  The energy transfer that happens when matter undergoes change.  Study of the interaction between two elements  Study of properties and changes of matter and energy Biochemistry  Study of processes that take place in organisms.  Understand the structure of matter found in the human body and the chemical changes that occur in cells Science What? Why? How? When? Science and Technology  Theoretical Chemistry-Design of new compound and new ideas; 2 categories: pure and applied  Science  Pure  Does not necessarily have an application; just knowing for knowledge’s sake; research  Technology  Applied  Has practical applications in society  Directed toward a practical goal/application  Engineering Alchemists (~300BC-1650 AD) China, India, Arabia, Europe, Egypt •Aiming to: Change common metals to gold. Develop medicines. •Developed lab equipment. •Mystical. Antoine Lavoisier (France 1743-1794)  Regarded as the Father of Chemistry  Designed equipment  Used observations and measurements.  Discovered nitrogen  Law of Conservation of Mass The Scientific Method Steps followed during scientific investigations Logical, problem solving technique Fathers of the scientific method is Galileo Galilei and Francis Bacon Scientific Method  Observation- recognition of a problem  Visible or provable fact  From that a question arises (problem statement)  Problem statement is a question that compares variables  Example: Does the amount of salt in water affect the boiling temperature of water? Scientific Method  Hypothesis- a proposed explanation of an observation  an educated guess  must be testable  Is a statement NOT a question that expresses the expected answer to the problem statement (what you think the results of the experiment will show)  If you increase the amount of salt added to the water, the boiling temperature will also increase because Scientific Method  Experiment- an organized procedure used to test a hypothesis (measurement, data collection, manipulated and responding variables)  Planned way to test the hypothesis and find out the answer to the problem posed  Way to collect data and determine the value of the dependent variable  Compares independent variable to the dependent variable  Can only test one dependent variable at a time Scientific Method  3 parts to an experiment  Control-standard for comparison  Variables  Independent Variable  Dependent Variable  Constants-parts of your experiment that do not change Scientific Method  Independent Variable  A variable that changes unrelated to other factors  A variable we manipulate, change, on purpose  A variable whose value we know before we start an experiment  Example: Does the amount of salt in water affect the boiling temperature of water? We know how much salt we add to each amount of water before boiling so amount of salt is the independent variable Scientific Method  Dependent Variable  A variable that changes depending on some other factors  The variable we are trying to find out  Variable whose value we do not know before we start the experiment  Example: Does the amount of salt in water affect the boiling temperature of water? We do not know the boiling temperature to water once salt is added; must test to find this out Scientific Method  Constants  Does not change for the duration of the experiment  Remains the same  Example: Does the amount of salt in water affect the boiling temperature of water? We would not change the brand of salt or the amount of water (or type of water) Scientific Method  Analyze  Look for patterns in experimental data  2 types of data  Quantitative = numbers  Qualitative = observations  Data presented via tables or graphs  3 types of graphs: circle (pie), bar, line Scientific Method The cafeteria wanted to collect data on how much milk was sold in 1 week. The table shows the results. We are going to take this data and display it in 3 different types of graphs. Day Chocolate Strawberry White Monday Tuesday Wednesday Thursday Friday 53 72 112 33 76 78 97 73 78 47 126 87 86 143 162 Scientific Method  Bar Graph Chocolate Milk Sold 120 112 100 Amount Sold  A bar graph is used to show relationships between groups.  The two items being compared do not need to affect each other.  It's a fast way to show big differences. Notice how easy it is to read a bar graph.  Often used for counting. 80 76 72 60 53 40 33 20 0 Monday Monday Wednesday F id Tuesday Tuesday Thursday Wednesday Day Thursday Friday Scientific Method  Circle graph (a.k.a. pie chart)  Used to show how a part of something relates to the whole.  This kind of graph is needed to show percentages effectively.  Sum of parts is 1 or 100% Chocolate Milk Sold Monday Tuesday Wednesday Thursday Friday Scientific Method  Line Graph Chocolate MIlk Sold 120 100 Amount Sold  A line graph is used to show continuing data; how one thing is affected by another.  It's clear to see how things are going by the rises and falls a line graph shows.  Equation of line represents the data. 80 60 40 20 0 Monday Tuesday Wednesday Day Chocolate Thursday Friday Scientific Method  Choosing the right graph for your data  Use a bar graph if you are not looking for trends (or patterns) over time; and the items (or categories) are not parts of a whole.  Use a pie chart if you need to compare different parts of a whole, there is no time involved and there are not too many items (or categories).  Use a line graph if you need to see how a quantity has changed over time. Line graphs enable us to find trends (or patterns) over time. Scientific Method  Conclusion  Presents the findings of the experiment, what the data shows, the hypothesis and whether or not it was correct (supported) or incorrect (negated)  Theorizes why the observed pattern is so Scientific Method  Communicate  When scientists collaborate (work together) and communicated, they increase the likelihood of a successful outcome  Journals  Internet  Presentations/Speeches Observations vs. Inferences  Observation  Something you confirm, something you have seen, a fact  A piece of information about circumstances that exists or events that have occurred  Inference  An abstract or general idea derived from specific instances  Idea, thought, concept, notion, opinion Theory  A well tested explanation for a broad set of observations.  May use models.  May allow predictions.  Theories may change to explain new observations or experimental data. Law  A statement that summarizes results of observations, but does not explain them.  Concise statement that summarizes the results of many observations and experiments  Changes or is abandoned when contradicted by new experiments. Note:  The order of the steps can vary and additional steps may be added. “No number of experiments can prove me right; a single experiment can prove me wrong.” Albert Einstein Math and Chemistry  Math- the language of Science      SI System (Metric System) Factor Label Method (Dimensional Analysis) Significant Figures Scientific Notation Manipulating Formulas Units  SI Units – International System  Basic Units Length Mass Time (meter) (kilogram) (second) abbreviation m kg s 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?