Chemistry is a “science” A science is a body of organized knowledge that is continuously updated...
-
Upload
charles-harrison -
Category
Documents
-
view
216 -
download
1
Transcript of Chemistry is a “science” A science is a body of organized knowledge that is continuously updated...
![Page 1: Chemistry is a “science” A science is a body of organized knowledge that is continuously updated through inquiry – includes testable explanations and predictions.](https://reader030.fdocuments.in/reader030/viewer/2022032707/56649e355503460f94b2359f/html5/thumbnails/1.jpg)
Chemistry is a “science”
• A science is a body of organized knowledge that is continuously updated through inquiry – includes testable explanations and predictions
![Page 2: Chemistry is a “science” A science is a body of organized knowledge that is continuously updated through inquiry – includes testable explanations and predictions.](https://reader030.fdocuments.in/reader030/viewer/2022032707/56649e355503460f94b2359f/html5/thumbnails/2.jpg)
Chapters 1 & 2Matter and Change
![Page 3: Chemistry is a “science” A science is a body of organized knowledge that is continuously updated through inquiry – includes testable explanations and predictions.](https://reader030.fdocuments.in/reader030/viewer/2022032707/56649e355503460f94b2359f/html5/thumbnails/3.jpg)
The study of the composition of matter and the changes that matter undergoes.
There are five branches:Organic, inorganic, analytical, physical, and biochemistry
1.1 Chemistry
![Page 4: Chemistry is a “science” A science is a body of organized knowledge that is continuously updated through inquiry – includes testable explanations and predictions.](https://reader030.fdocuments.in/reader030/viewer/2022032707/56649e355503460f94b2359f/html5/thumbnails/4.jpg)
Pure vs Applied Chemistry
• Pure chemistry-
• What does a chemist do?
• making nylon
• Applied chemistry-
![Page 5: Chemistry is a “science” A science is a body of organized knowledge that is continuously updated through inquiry – includes testable explanations and predictions.](https://reader030.fdocuments.in/reader030/viewer/2022032707/56649e355503460f94b2359f/html5/thumbnails/5.jpg)
Why Chemistry?
• Understanding natural world
• Preparing for a career
• Being an informed citizen
![Page 6: Chemistry is a “science” A science is a body of organized knowledge that is continuously updated through inquiry – includes testable explanations and predictions.](https://reader030.fdocuments.in/reader030/viewer/2022032707/56649e355503460f94b2359f/html5/thumbnails/6.jpg)
1.3 The Scientific Method
An approach to problem-solving
Observation of a problem
Hypothesis: educated guess, possible solution
Experiment: collecting data, testing variables
Theory: well-tested explanation, conclusion
Scientific Method
Law- a statement of fact regarding natural phenomenon, does not explain why.
![Page 7: Chemistry is a “science” A science is a body of organized knowledge that is continuously updated through inquiry – includes testable explanations and predictions.](https://reader030.fdocuments.in/reader030/viewer/2022032707/56649e355503460f94b2359f/html5/thumbnails/7.jpg)
2.1 Properties of Matter
• Physical Properties help identify a substance. They can be observed or measured without changing the substance’s composition.
• Ex. Color, texture, hardness, density, melting point, boiling point, solubility
(See examples on p R47- 49)
![Page 8: Chemistry is a “science” A science is a body of organized knowledge that is continuously updated through inquiry – includes testable explanations and predictions.](https://reader030.fdocuments.in/reader030/viewer/2022032707/56649e355503460f94b2359f/html5/thumbnails/8.jpg)
• Chemical properties are described as the ability of a substance to change in composition. They are observed when a substance undergoes a chemical change.
• Ex. Flammability, Corrosiveness, reacts with ….
![Page 9: Chemistry is a “science” A science is a body of organized knowledge that is continuously updated through inquiry – includes testable explanations and predictions.](https://reader030.fdocuments.in/reader030/viewer/2022032707/56649e355503460f94b2359f/html5/thumbnails/9.jpg)
Properties of Potassium • Potassium is a metal and is the seventh most abundant and
makes up about 1.5 % by weight of the earth's crust. Potassium is an essential constituent for plant growth and it is found in most soils. It is also a vital element in the human diet.
• Potassium is never found free in nature, but is obtained by electrolysis of the chloride or hydroxide, much in the same manner as prepared by Davy. It is one of the most reactive and electropositive of metals and, apart from lithium, it is the least dense known metal. It is soft and easily cut with a knife. It is silvery in appearance immediately after a fresh surface is exposed.
• It oxidizes very rapidly in air and must be stored under argon or under a suitable mineral oil. As do all the other metals of the alkali group, it decomposes in water with the evolution of hydrogen. It usually catches fire during the reaction with water. Potassium and its salts impart a lilac color to flames.
![Page 10: Chemistry is a “science” A science is a body of organized knowledge that is continuously updated through inquiry – includes testable explanations and predictions.](https://reader030.fdocuments.in/reader030/viewer/2022032707/56649e355503460f94b2359f/html5/thumbnails/10.jpg)
2.1 States of Matter• Solids – rigid, not compressible, molecules
tightly packed.
• Liquids – definite volume, but not shape, molecules close, but able to move
• Gases - are compressible, take the shape and volume of the container. Molecules are spaced farther apart.
• Plasmas – occur at very high temperatures and energies. Electrons leave the nucleus.
![Page 11: Chemistry is a “science” A science is a body of organized knowledge that is continuously updated through inquiry – includes testable explanations and predictions.](https://reader030.fdocuments.in/reader030/viewer/2022032707/56649e355503460f94b2359f/html5/thumbnails/11.jpg)
2.1, 2.4 Changes
• Physical changes do not change the composition of the substance.
Ex. Grinding, melting, boiling
• Chemical changes result in the formation of a new substance(s).
Ex. Burning, corroding, gas formation,
precipitates forming
![Page 12: Chemistry is a “science” A science is a body of organized knowledge that is continuously updated through inquiry – includes testable explanations and predictions.](https://reader030.fdocuments.in/reader030/viewer/2022032707/56649e355503460f94b2359f/html5/thumbnails/12.jpg)
2.2 Mixtures• A physical blend of two or more substances. They can be separated by simple means using
the differences in their physical properties. Ex. Filtering, sifting, distilling, using a magnet
• Two types of mixtures: Heterogeneous – more than one phase can be
observed. They are not uniform throughout.
Homogenous- appears uniform throughout Sometimes called solutions
![Page 13: Chemistry is a “science” A science is a body of organized knowledge that is continuously updated through inquiry – includes testable explanations and predictions.](https://reader030.fdocuments.in/reader030/viewer/2022032707/56649e355503460f94b2359f/html5/thumbnails/13.jpg)
2.3 Pure Substances
Pure substances are classified as either an element or a compound.
• Elements are the simplest types of matter. They are the building blocks for all substances. Presently there are118 known elements.
• Each element is represented by a chemical symbol and found on a periodic table.
![Page 14: Chemistry is a “science” A science is a body of organized knowledge that is continuously updated through inquiry – includes testable explanations and predictions.](https://reader030.fdocuments.in/reader030/viewer/2022032707/56649e355503460f94b2359f/html5/thumbnails/14.jpg)
• Compounds are two or more elements that are combined chemically. These can be broken down only by a chemical reaction.
• Compounds are represented by chemical formulas, which show the type of atoms, and the proportions which they are combined.
Ex. AgNO3
Shows 1 atom of silver, 1 atom of nitrogen and 3 atoms of oxygen combine to form silver nitrate.
![Page 15: Chemistry is a “science” A science is a body of organized knowledge that is continuously updated through inquiry – includes testable explanations and predictions.](https://reader030.fdocuments.in/reader030/viewer/2022032707/56649e355503460f94b2359f/html5/thumbnails/15.jpg)
2.4 Chemical Reactions• During chemical reactions, a chemical change
takes place and a new substance forms.
• The starting substances are called “reactants” and the new substances are called “products”
• We can represent a chemical reaction by writing a chemical equation.
Ex. Iron + Sulfur -- Iron Sulfide
(reactants) (product)
![Page 16: Chemistry is a “science” A science is a body of organized knowledge that is continuously updated through inquiry – includes testable explanations and predictions.](https://reader030.fdocuments.in/reader030/viewer/2022032707/56649e355503460f94b2359f/html5/thumbnails/16.jpg)
2.4 Law of Conservation of Mass
• In any physical or chemical change, mass is neither destroyed nor created. The total mass will remain the same.
![Page 17: Chemistry is a “science” A science is a body of organized knowledge that is continuously updated through inquiry – includes testable explanations and predictions.](https://reader030.fdocuments.in/reader030/viewer/2022032707/56649e355503460f94b2359f/html5/thumbnails/17.jpg)
2.3 grams of zinc react with 5.8 grams of hydrogen chloride to produce zinc chloride and hydrogen gas.
Identify the reactants.
Identify the products.
What is the total mass of the products formed?