Chem Lesson 1 PDF

Lesson 1: Introduction to Chemistry Chemistry 1 Kenneth June E. Lebrillo Introduction to Chemistry After going through this chapter, you are expected to: 1. Discuss how chemistry started; 2. Define chemistry and differentiate its branches; 3. explain the importance of chemistry to hu...

Lesson 1: Introduction to Chemistry Chemistry 1 Kenneth June E. Lebrillo Introduction to Chemistry After going through this chapter, you are expected to: 1. Discuss how chemistry started; 2. Define chemistry and differentiate its branches; 3. explain the importance of chemistry to human lives and society; 4. describe the steps in a scientific investigation; and 5. adopt a scientific mindset in solving problems encountered every day. Lesson 1.1 History of Chemistry ❑Chemistry is a branch of science that deals with the study of matter. It studies the composition, properties, structure, and the changes matter undergoes. ❑Like all other sciences, chemistry began in the prehistoric era and prospered in the modern time. ❑The first attempts to describe natural phenomenon contribute to fanciful inventions - to myths and fantasies - but not to understanding. Lesson 1.1 History of Chemistry ❑About 600 B.C., these myths and fantasies dissatisfied a group of Greek philosophers. Driven by social and cultural changes and curiosity, they started to ask questions about the world around them. ❑Through experiments, they were able to discover fundamental truths of nature. ❑The years between 600 B.C. and 400 B.C. are called the "Golden Age of Philosophy". Lesson 1.1 History of Chemistry ❑Some of the Greek philosophers believed they could find a single substance from which everything else was made. ❑Thales believed that it was water and Anaximenes thought it was air. ❑Empedocles' idea was that the universe is made of four elements namely earth, air, fire and water. Lesson 1.1 History of Chemistry ❑Leucippus and Democritus believed that matter was made of small, indivisible particles which they called atomos (atom), a particle that could not be seen. ❑Two thousand years later scientists proved that this idea was true. Lesson 1.1 History of Chemistry ❑The Egyptians gave birth to khemia which became the English word alchemy, a practice of transforming common metals such as lead and copper into precious metals like gold and silver. ❑They were making embalming fluids and dyes. ❑Alchemists tried to find the "philosopher’s stone", a supposed cure for all diseases, and the "elixir of life" which would prolong life indefinitely. Lesson 1.1 History of Chemistry ❑They failed in both attempts but along the way, they were able to discover acetic acid, nitric acid, ethyl alcohol and other substances used by chemists today which served as the beginning of chemistry. ❑The modern age of Chemistry began in 1661 when Robert Boyle, an English chemist, published his book The Sceptical Chymist. ❑His idea opposed the Greek's four-element composition of matter. Lesson 1.1 History of Chemistry ❑Boyle described an element as a substance that cannot be broken down into simpler substances. ❑He also established the law relating volume and pressure. These discoveries made him the "Forerunner of Modern Chemistry". ❑In 1770, Lavoisier's observations on the nature of combustion and the conservation of mass during chemical reactions paved the way for the booming of modern chemistry. Thus, he became known as the "Father of moder chemistry". Lesson 1.1 History of Chemistry ❑In 1772, he stated that when burned sulfur and phosphorus increased in weight because they absorbed "air". ❑On the other hand, the metallic lead formed when litharge was heated with charcoal weighed less than the original litharge because it had lost "air.“ ❑He gave phlogisticated air the name oxygen, or "acid producer". He explained phlogiston theory as the result of the combination of the burning substance with oxygen. This theory was later revised and now known as the theory of combustion.  Timeline in Chemistry Thales (600 Anaximenes Empedocles B.C.) (546 B.C) (450 B.C.) Idea that Idea that air Idea that the four elements - water is the is the main earth, air, fire main form form of and water of matter matter combine in different proportions  Timeline in Chemistry Leucippus and Robert H. Cavendish Democritus (420 (1766) B.C.) Boyle (1661) Idea of the The Discovery atom or the Age of Sceptical of Atomism Chymist hydrogen  Timeline in Chemistry A. Lavoisier John Dalton John Jacob (1775) (1800) Berzelius(1820) Discovery of Proposed Devised the the modern the symbols of composition of air Atomic elements Theory  Timeline in Chemistry Dmitri Eugene J.J. Thomson Mendeleev Goldstein (1897) (1869) (1886) Periodic Law Naming of Proposed and designed cathode rays the Modern the structure and discovery Periodic Table of of proton of the atom; Elements discovery of electron  Timeline in Chemistry Ernest Rutherford Niels Bohr (1913) (1911) Proposed the Proposed the nuclear atom; energy levels in discovery of a atoms nucleus Lesson 1.2 Branches of Chemistry The study of Chemistry is divided into five important branches. ❑Organic Chemistry deals with the study of carbon-based substances, particularly those that affect or constitute living organisms. This branch of chemistry is important to the petrochemical, pharmaceutical and textile industries. All living organisms have traces of carbon. Lesson 1.2 Branches of Chemistry ❑Inorganic Chemistry deals with the study of substances that contain little or no carbon, including metals and minerals. These substances are nonbiological in nature. ❑Physical Chemistry deals with the behavior of matter in chemical systems at the molecular and atomic levels. ❑Biochemistry is a science that fused biology and chemistry. The study of the chemical processes within living organisms. Lesson 1.2 Branches of Chemistry ❑Analytical Chemistry deals with the theory and practice of methods used to determine the composition of substances. It seeks to improve means of measuring chemical composition of natural and artificial materials. In medicine, this is the basis for clinical laboratory tests for disease diagnosis. The nutritional value of the food we eat is determined through chemical analysis. Analytical chemists analyze many household products. Lesson 1.2 Branches of Chemistry Importance of Chemistry ❑Chemistry has undeniable significance in different areas of life. ❑Some people view chemistry as a very technical subject that deals with formulas and mind- boggling computations. This may be true, but if you will try to look at things around you, you will begin to appreciate its importance. ❑The products of chemistry and technology are highly useful. Lesson 1.2 Branches of Chemistry Importance of Chemistry ❑For example, when you go to a beauty salon and ask the hair stylist to straighten or curl your hair, she/he needs to use a correct solution, or else it will not come out right. ❑Chemistry also plays a very important role in food industry, biotechnology, medicine, engineering, agriculture, photography, and other related fields. Lesson 1.3 Scientific Investigation ❑Chemists, like any experts in science, conduct scientific investigations to acquire knowledge and solve problems. ❑A scientific investigation is a systematic approach to solving problems or studying a phenomenon and communicating the results and implications to the scientific community. ❑Doing a scientific investigation involves a series of steps collectively referred to as the scientific method. Lesson 1.3 Scientific Investigation The basic Observe steps in the scientific Ask a Question method are: Gather Information Form a Hypothesis Perform Experiment Record and Analyze the Data Draw a Conclusion Communicate Results Lesson 1.3 Scientific Investigation 1. Observe Identifying or knowing what you want to investigate or study. Lesson 1.3 Scientific Investigation 2. Ask a Question Formulate a question from what was observed then state the problem. Think about what you want to learn and why you want to know it. Lesson 1.3 Scientific Investigation 3. Gather Information Jotting down important data or information gathered through reliable references. This includes finding out if the question or related queries has been asked before and how it was studied and solved. Lesson 1.3 Scientific Investigation 4. Form a Hypothesis Hypothesis is an educated guess or a testable explanation to the question. Forming this would help you find out what the answer to your problem might be. There are two types of hypothesis: null and alternative. Lesson 1.3 Scientific Investigation 5. Perform Experiment Design and carry out an experiment to validate or negate the hypothesis. Observe everything you can. The smallest detail can sometimes be the most significant. Lesson 1.3 Scientific Investigation Identify the variables that include (a)independent variable - variable that is changed and manipulated by the scientist. (b)dependent variable - the variable that the scientist observes or measures to see the change made by the independent variable. (c)controlled variable - remains constant or the same all throughout the experiment. Lesson 1.3 Scientific Investigation 6. Record and Analyze the Data Interpret and evaluate the information gathered. Do calculations if needed to come up with your conclusion. Lesson 1.3 Scientific Investigation 7. Draw a Conclusion Two possible conclusions can be made based on the results of the analysis: did the experiment support the hypothesis for it to be regarded as true, or did the experiment disprove the hypothesis for it to be regarded as false? The conclusion should be supported well by the results. Lesson 1.3 Scientific Investigation 8. Communicate Results Results should be communicated through written, oral reports, or posters. The report must be replicable and easy to understand to allow other researches repeat the experiment to validate the results. Lesson 1.3 Scientific Investigation ❑Scientists run an experiment setup and a control setup to make sure the results of the experiment were caused by the variable and not by some hidden factors. ❑Discoveries in science sometimes occur by luck or by accident. This is called serendipity.