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