Download - Lecture 1&2
Md. Faysal Ahamed Khan
Welcome to the class of Chemistry ICourse No. CHEM 211
Credit hours 3
1. To better understand the world: what it is made of and how it works.
2. Because it is the most practical and relevant of the sciences - chemistry is the study of EVERYTHING!
3. It is the “Central Science” - All other sciences intersect at and depend on chemistry.
4. It is essential to the national and local economies.
5. It is required for virtually every major involving science or engineering.
6. An awareness of the principles of chemistry is essential to being an informed and responsible citizen in a highly technical society.
7. It is incredibly fascinating and a lot of fun!
Chemistry is the study of the properties, composition,
and structure of matter, the physical and chemical
changes it undergoes, and the energy associated (liberated or
Absorbed) during those changes.
Anything that has mass and occupies space
Ex: oxygen, air, chair, water, rocks, gasoline
Atoms are the building blocks of matter. Each element is made of the same kind of atom. A compound is made of two or more different kinds of elements.
Physical: properties that can be measured without changing the chemical composition of the substance – E.g. melting point, density.
Chemical: properties that described a substance’s reactivity. E.g. rusting is a chemical property of Iron,
EOS
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A physical change is one that does not occurs any change in chemical composition
Water freezing to form ice
Iron melting in a blast furnace
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A chemical change involves a change in chemical composition
Iron Rusting
Natural gas burning
Problem 1: What is a physical change? List the physical changes that occur when one makes cheese.
Ans: Physical changes include:1. Dissolving of salt in water
2. Evaporation of water from solution 3. Stirring to mix
Problem 2: What is a chemical change? List the chemical changes that occur when one makes cheese.
Ans: changes include:1. bacteria convert the sugar in milk (lactose) to lactic acid2. special bacteria ferment the remaining lactose and produce carbon dioxide bubbles in the cheese.
Air
sugar in waterWater
Salt
GoldSalad
Can it be separated by any physical process?
Is the composition uniform? Can it be decomposed chemically?
Matter
Mixtures Pure substances
yes No
yes No
yes
No
Homogeneous mixture
(Solution)
Heterogeneous mixture
Compounds Elements
MatterMatter
SubstancesSubstances MixturesMixtures
ElementsElements CompoundsCompoundsHomogeneousHomogeneous
(Solutions)(Solutions)
HeterogeneousHeterogeneous
Based on the previous classification scheme, can you classify the kinds of matter illustrated?
• Which can be separated?
Air sugar in
water
• So, these are Mixtures!
But which type of mixtures?
Homogeneous or heterogeneous?
Salad
Uniform Not uniform
Air
sugar in water
Homogenous Mixtures
Heterogeneous Mixtures
Salad
Now...
Those that can’t be separated are Pure Substances
WaterSalt
Gold
Bur are they Compounds or Elements?
Which can be decomposed by chemical means, like heating, electricity...and which cannot?
Compounds Elements
Water
SaltGold
Matter can be classified into: Mixtures and pure substances.
Mixtures can be homogenous or heterogeneous. Homogeneous mixtures: Uniform Heterogeneous mixtures: Not Uniform
Pure substances can be elements or compounds. Elements can’t be decomposed. Compounds can be decomposed by chemical means.
21GAS
LIQUID
SOLID
Water as example
Commonly, a given kind of matter exists in different physical forms under different conditions. For example: water exists as ice (solid), as liquid water and as steam (gaseous water).
Solid: the form of matter characterized by rigidity; a solid is relatively incompressible and has fixed shape and volume.
Liquid: the form of matter that is a relatively incompressible fluid; a liquid has a fixed volume but no fixed shape.
Gas: the form of matter that is an easily compressible fluid; a given quantity of gas will fit into a container of any size and shape.
The three form of matter-solid, liquid, and gar-are referred to as thestate of matter.
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STATES OF MATTER
Shape Volume
Gas indefinite indefinite
Liquid indefinite definite
Solid definite definite
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A one- or two-lettered designation derived from the name of the element
EOS
Note that the first letter is always capitalized and the second is lowercase
Most symbols are based on English names:
Hydrogen = H Neon = Ne Chromium = Cr
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In some cases, symbols come from Latin names