Presentation on theme: "What is Chemistry Introduction 3221.Inq.1, 3221.T/E.1, 3221.T/E.2, 3221.T/E.4."— Presentation transcript:
What is Chemistry Introduction 3221.Inq.1, 3221.T/E.1, 3221.T/E.2, 3221.T/E.4
Why has ozone been broken down in the atmosphere? CFCs (chlorofluorocarbons) are broken down by UV light. Cl is released which causes the breakdown of O 3. Cl + O 3 ClO + O 2
Why does an iron nail rust when exposed to air and rain? 4Fe(s) + 3O 2 (g) 2Fe 2 O 3 (s)
Why does aspirin or ibuprofen help a headache? These are members of the NSAID family (non- steroidal anti-inflammatory drugs) During an injury, the body releases prostaglandins. Aspirin acts to prevent the production of prostaglandins, thereby reducing inflammation, pain, and fever.
What causes plants to grow? Photosynthesis: process by which plants covert CO 2, H 2 O, and energy into carbohydrates (glucose) that are usable by the plant.
What is chemistry? Study of the composition, structure, properties, and reactions of matter The connections between the behavior of matter and the behavior of the particles that compose it
Chemistry in your everyday life… ChemicalPurpose Calcium carbonateAn abrasive used to remove plaque SorbitolPrevents loss of water and hardening of toothpaste Carrageenan (seaweed) Keeps toothpaste from hardening or separating GlycerinMakes toothpaste foam in mouth Sodium lauryl sulfateDetergent used to loosen plaque Titanium dioxideMakes the toothpaste base white and opaque TriclosanAn antibacterial agent used to inhibit bacteria that cause plaque and gum disease Sodium monofluorophosphate Prevents formation of cavities by strengthening tooth enamel with fluoride Methyl salicylate Gives pleasant flavor of wintergreen
More chemistry uses Cosmetics and lotions: chemicals are used to moisturize, prevent deterioration of the product, fight bacteria, and thicken the product. Cereal: fortified with iron, calcium, and phosphorus Milk: enriched with vitamins A and D
Some definitions Chemical: any material used in or produced by a chemical process Matter: anything that has mass and takes up space Substance: chemical that consists of one type of matter and always has the same composition and properties wherever it is found Mass: amount of a substance grams (g)
Scenario: Jason goes to Sally’s house after school on a brisk winter day. He is going to see the new kitten Sally got for Christmas. Soon after arriving, his eyes start to itch and he begins to sneeze. Why is Jason reacting this way? How can this be tested? What are other possibilities?
The Scientific Method Approach to problem solving that emphasizes observation and experimentation Characterized by four steps 1.Observation of nature 2.Formulation of hypothesis 3.Testing of hypothesis by experiment 4.Formulation of laws and theories
Observation Can occur intentionally or “by chance” 1. Antoine Lavoisier, a French chemist studying combustion, made careful measurements on the mass of objects before and after burning them in closed containers 2. Alexander Fleming discovered penicillin when he observed a bacteria-free circle around a blue- green mold had accidentally grown on his culture plate of Staphylococcus
Observation (cont’d) Data: written observations There are two types of data: 1. Qualitative (quality) -descriptions that involve the senses: color, taste, smell, texture, etc. 2. Quantitative (quantity) -any information involving measurement (i.e. numbers): mass, density, temperature, energy -allows scientists to precisely specify a difference in measurements
Hypothesis A tentative interpretation or explanation of the observations. A good hypothesis is falsifiable—further testing has the potential to prove it wrong.
Experiments Highly controlled observations designed to validate or invalidate hypotheses. The results of an experiment may confirm a hypothesis or show it to be mistaken in some way. The hypothesis may later have to be modified or discarded and replaced by an alternative.
“It’s just a theory.” Theory: explanation of observed events based on well-established hypotheses – Atomic theory “Well tested theories are as close to truth as we get in science.” (Nivaldo Tro in Intro Chem. 3 rd ed) Law: brief statement that summarizes past observations and predicts future ones – Law of gravity, law of conservation of mass BOTH laws are theories are subject to the results of further experimentation
Science and Technology Basic research: carried out for the sake of increasing knowledge Applied research: carried out to solve a problem Technology: production and use of products that improve our quality of life
Some important Scientific and Technological Discoveries DiscoveryDateNameCountry Law of Gravity1687Isaac NewtonEngland Oxygen1774Joseph PriestlyEngland Atomic Theory1803John DaltonEngland Anesthesia, ether1842Crawford LongU.S. Germ theory1865Louis PasteurFrance Antiseptic surgery1865Joseph ListerEngland Discovery of Radium1898Marie and Pierre CurieFrance Quantum theory1900Max PlankGermany Theory of Relativity1905Albert EinsteinGermany Penicillin1928Alexander FlemingEngland Cellular Phones1973Martin CooperU.S. Prozac1988Ray FullerU.S. HIV protease inhibitor1995Joseph Martin, Sally RedshawU.S.
Identify each of the following as an observation or a hypothesis. Determine whether observations are qualitative or quantitative. a.A silver tray turns a dull gray color when left uncovered. b.Water freezes at 0˚ Celcius. c.Ice cubes have a greater volume than the liquid from which they were formed because the water molecules are further apart in the ice structure than in liquid form.
The following statements are found in a student’s botany notebook. Identify each of the following as (1) observation, (2) hypothesis, or (3) experiment. a.“Today, I planted two tomato seedlings in the garden. Two more tomato seedlings are placed in a closet. I will give all the plants the same amount of water and fertilizer.” b.“After fifty days, the tomato plants in the garden are 3 feet high with green leaves. The plants in the closet are 8 inches tall and yellow.” c.“Tomato plants need sunlight to grow.”
Classify each of the following as an observation, a law, or a theory The star closest to Earth is moving away from Earth at a high speed. A body in motion stays in motion unless acted upon by a force. The universe began as a cosmic explosion called the Big Bang. A stone dropped from an altitude of 450 m falls to the ground in 9.6 s.
Matter and its Properties Investigate the characteristic properties of matter
Vocabulary Atom: smallest unit of an element that maintains the chemical identity of that element Element: pure substance that cannot be broken down into simpler, stable substances and is made up of one type of atom Molecule: smallest unit of an element or compound that retains all the properties of the element or compound Compound: substance that can be chemically broken down into simpler substances – Made from the atoms of 2 or more elements chemically bonded
Properties and Changes in Matter Intensive properties: do NOT depend on the amount of matter present – Melting point, boiling point, density, ability to conduct electricity Extensive properties: depend on the amount of matter that is present – Volume, mass, amount of energy
Physical Properties and Changes Physical property: a characteristic that can be observed without changing the identity of the substance – Melting point, boiling point Physical change: change in a substance that does not involve a change in the identity of the substance – Grinding, cutting, melting, boiling
Change of State Physical change of a substance from one state to another (melting, boiling, sublimation, condensation, evaporation) States of matter 1.solid: definite volume and definite shape 2.Liquid: definite volume, indefinite shape 3.Gas: neither definite volume nor definite shape 4.Plasma: high temperature physical state of matter in which atoms lose most of their electrons -found in fluorescent light bulbs
Physical Properties/Changes cont’d
Chemical Properties and Change Chemical property: relates to substance’s ability to undergo changes that transform it into different substances Chemical change (reaction): change in which one or more substances are converted into different substances
Chemical Reaction Reactants: substances that react in a chemical change Products: substances that are formed by the chemical change Carbon + oxygen carbon dioxide “carbon plus oxygen yields carbon dioxide”