Taing You, Ph.D.

1. Introduction to Environmental ScienceWe do NOT Inherit the Earth from our Ancestors, We BORROW it from our Children. Taing You, Ph.D.

2. LESSON 4: Interrelated Scientific Principles: Matter, Energy and Environment SCIENTIFIC THINKING • Environment involves the analysis of data, so it is useful to understand how scientists gather and evaluate information. It is also important to understand some chemical and physical principles as background for evaluating environmental issues.

3. THE SCIENTIFIC METHOD • Science - is the process used to solve problems or develop an understanding of nature that involves testing possible answers. Science is distinguished from other fields of study by how knowledge is acquired rather than what is studied. • Scientific Method – a way of gaining information (facts) about the world by forming possible solutions to questions, followed by rigorous testing to determine if the proposed solutions are valid.

4. When scientists use the scientific method, they make several fundamental assumptions: • There are specific causes for events observed in the natural world. • The causes can be identified; • There are general rules or patterns that can be used to describe what happens in nature; • An event that occurs repeatedly probably has the same cause; • What one person perceives can be perceived by others; and • The same fundamental rules of nature apply regardless of where and when they occur.

6. OBSERVATION – occurs when we use our senses (smell, sight, hearing, taste, touch) or an extension of our senses (microscope, tape recorder, X-ray machine, thermometer , etc) to record an event. • Observation is more than a casual awareness. • When scientists talk about their observations, they are referring to careful, thoughtful recognition of an event – not just casual notice. Scientists train themselves to improve their observational skills, since careful observation is important in all parts of the scientific method.

7. 2. Questioning and Exploring – observations often lead one to ask questions about the observations. Why did this event happen? Will it happen again in the same circumstance? • The formation of the questions is not as simple as it might seen, because the way the questions are asked will determine how you go about answering them. • In some situations this can be the most time-consuming part of the scientific method. Asking the right question is critical to how you look for the answers.

8. 3. Constructing Hypothesis • Hypothesis – a statement that provides a possible answer to a question or an explanation for an observation that can be tested. • A good hypothesis must be logical, account for all relevant information currently available, allow one to predict future events relating to the question being asked and be testable. • If one has the choice of several competing hypotheses, one should use the simplest hypothesis with the fewest assumptions.

9. 4. Testing Hypothesis – the test of a hypothesis can take several forms. It may simply involve the collection of pertinent information that already exists from a variety of sources. • Another common method for testing hypothesis involves devising an experiment. An experiment is a re-creation of an even or occurrence in a way that enables a scientist to support or disprove a hypothesis. • This can be difficult because a particular event may involve a great many separate happenings called variables.

10. The best experimental design is a controlled experiment in which two groups differ in only one way. • The concept of reproducibilityis important to the scientific method. Because it is often not easy for scientists to eliminate unconscious bias, independent investigation must be able to reproduce the experiment to see if they get the same results. If a hypothesis is supported by many experiments and by different investigators, it is considered reliable.

11. 5. The Development of Theories and Laws • Theory – is widely accepted, plausible generalization about fundamental concepts in science that explains why things happen. An example of a scientific theory is the kinetic molecular theory, which states that all matter is made up of tiny, moving particles. • A scientific law is a uniform or constant fact of nature that describes what happens in nature. An example of scientific law is the law of conservation of mass, which states that matter is not gained or lost during chemical reaction.

12. THE STRUCTURE OF MATTER • Matter – Anything that takes up space and has mass. Air, water, trees, cement, and gold are all examples of matter. • Atomic structure • Atoms - are fundamental subunits of matter. They are made up of protons, neutrons and electrons. There are 92 kinds of atoms found in nature. Each kind forms a specific type of matter known as an element. Gold (Au), oxygen (O) and mercury (Hg) are examples of elements. • Isotopes – atoms of the same element that differ from one another in the number of neutrons they contain. For example, there are three isotopes of the element hydrogen.

13. Classification of matter

15. Relationship of the three states SOLID Solidification Freezing Solidification Melting Sublimation Evaporation GAS LIQUID Condensation

17. Atomic structure Atom Electron Nucleus Neutron Proton

18. Atomic structure

19. Molecules: Atoms in combination

21. ACIDS, BASES and pH • Acid - is any compound that releases hydrogen ions (protons) in a solution. Examples of common acids are sulfuric acid (H2SO4) in car batteries and acetic acids (HCH2COOH) in vinegar. • Base – the opposite of acid as it accepts hydrogen ions in solution. Many common bases release hydroxide ions (OH-). This ion is composed of an oxygen atom and a hydrogen atom bonded together but with an additional electron. Sometimes people refer to a base as an alkali. • pH – the concentration of acid or base solution. The pH scale is a measure of hydrogen ion concentration.

24. INORGANIC AND ORGANIC MATTER • Organic Matter – consists of molecules that contain carbon atoms that are usually bonded to form chains or rings. Organic molecules can be very large. • Inorganic compounds – generally consist of small molecules and combination of ions and relatively few kinds exist.

25. CHEMICAL REACTIONS • Chemical bonds - attractive forces between atoms resulting from the interaction of their electrons. Each chemical bond contains a certain amount of energy. When chemical bonds are broken or formed, a chemical reaction occurs. • Chemical reactions that released energy as heat and light are called exothermic reactions. • Chemical reactions that absorbed energy as heat are called endothermic reactions. • Amount of energy required to start the reaction is called activation energy • Catalyst – a substance that alters the rate of a reaction, but the catalyst itself is not consumed or altered in the process.

26. CHEMICAL REACTIONS IN LIVING THINGS • Photosynthesis is the process plants use to convert inorganic material into organic matter, with the assistance of light energy. • Respiration involves the use of atmospheric oxygen to break down large organic molecules (sugars, fats and proteins) into smaller, inorganic molecules (carbon dioxide and water). This process releases energy the organisms can use.

29. ENERGY PRINCIPLES • ENERGY – The ability to do work. Work is done when an object is moved over a distance. • Kinetic Energy – energy contained by moving objects. The moving molecules in air have kinetic energy, as do water running downhill. • Potential Energy - is the energy matter has because of its position. Example. The water behind the dam has potential energy because it is in an elevated position.