INTRODUCTION TO CHEMISTRY

Chapter 1

ASTERINA ANGGRAINIMITA FADHILAHRARA SERUNI

Chemistry is a branch of science which deals with the properties of matter, structure of matter, changes in matter, the laws and principles describing these changes, and the concepts and theories that interpret them.

You have to study chemistry because chemistry is an important part to prepare your particular future career

1.1 Why should you study chemistry?

1.2 ELEMENTS• An elements is a fundamental substance that

can’t be chemically changed or broken down into anything simpler.

Periodik table of the elements

• The periodic table consists of 7 horizontal rows called PERIODS and 18 vertical columns called GROUPS.

• The elements in the periodic table are often divided into three mayor classes : NONMETAL, METAL, and SEMIMETAL (METALLOID)

1.3 Where did the elements come from?

Hydrogen and helium were came from the Big Bang. The atoms of hydrogen and helium collected together in large clouds. These clouds gradually became hotter and in due course they burst into incandescence as stars. Within the stars, intense heat causes atoms of hydrogen to smash together and became atoms of other elements. So, all the elements in the universe except hydrogen and most of the helium were made in the stars.

1.4 Compounds

Compound is a pure substance that is formed when atoms of two or more different elements combine and create a new material with properties completely unlike those of its constituent elements.

For example, when atoms of sodium (a soft, silvery metal) combine with atoms of chlorine (a toxic, yellow-green gas), the familiar white solid called sodium chloride or table salt (NaCl) is formed. The properties of sodium and chloride are different to those of sodium and chloride.

A compound is written by giving its chemical formula, which lists the symbols of the individual constituent elements and indicates the number of atoms of each element with subscript.

• Matter is • Any thing that occupies space

(volume) and has mass• Can be visible or invisible to the

naked age • All the many kind of matter can be

classified either pure substances and mixture.

1.5 Compounds and Mixture

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Matter

Mixture Pure Substance

ElementCompoundHeterogeneous Mixture

Homogeneous Mixture

Can be separated physically

Cannot be separated physically

Can see the parts

Cannot see the parts

Can be separated chemically

Cannot be separated

Most impure Most pure

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Matter Flowchart

Examples:

– graphite

– pepper

– sugar (sucrose)

– paint

– soda

element

hetero. mixture

compound

solution homo. mixture

hetero. mixture

A. Pure Substance • Pure Substance – Matter that has only 1 set of

chemical and physical properties. A pure substance:

• cannot be separated into 2 or more substances by physical or mechanical means

• its properties are constant throughout the whole sample

• has constant chemical composition• The two class of pure substance are Element

and Compound

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• Example: Pure water

If water ever tastes different then it isn’t pure water; it fits into our next category.

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Pure Substances• Elements – Substances made up of only one

type of atom. - Cannot be separated by any physical OR chemical process.

Examples:CarbonHeliumGold

Compound

Compound is a substance composed of atoms of two elements / more

chemically bound with afixed ratio

– composed of 2 or more elements in a fixed ratio

– properties differ from those of individual elements

– EX: table salt (NaCl)

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Pure Substances

• Compounds have only 1 set of properties. They cannot be separated by any physical process.- Can only be separated by a chemical reaction.

Water can be separated into Hydrogen and Oxygen by a process called Electrolysis.

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Separating compounds

• Compounds are made of molecules

• Compounds can be broken down into simpler substances by heating and electricity

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Classification of Matter• Mixture – Two or more pure substances mixed

together. Each substance in the mixture retains its own set of chemical and physical properties.

Unlike pure substances, mixtures can always be separated by physical means.

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Mixtures

• Some mixtures are more pure than others.• Heterogeneous mixture – Uneven distribution

of substances. (Very impure)- You can see the different parts.

Examples: SandGraniteWood

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Mixtures• Homogeneous Mixture – Components are evenly

mixed. (More pure than heterogeneous)

Salt water contains salt and water, but are mixed all the way to the atomic level , but it can still be separated by physical means.

- Cannot see the parts.

Seawater distillation plant

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Separating mixtures

• The substances in a mixture can be separated by simple physical means

• Evaporation and filtration are used to separate mixtures

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• Any characteristic that can be use to describe or identify matter is called properties

• Example include size, amount, colour, odor, temperature, solubility, and melting point.

• Properties can be classified as either intensive or extensive depending on whether their value change with size of sample

1.6 Some Properties Substance

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• Intensive properties like temperature and melting point,have the value that do not depend on the amount of sample. example : 1 gram and 1 kilogram of ice have melting point of 0 celcius at 1 atmospheris pressure

• Extensive properties like length and volume, have the value that do depend on the amount of sample.example : 1 kilogram of sugar is heavier than 1 gram of sugar

Intensive properties and Extensive properties

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• Physical properties are characteristics that do not involve a change in a sample’s chemical makeup. Example : the melting point and boiling point from ice to water cause to change only in from or phase, but do not in chemical makeup.

• Chemical properties are characteristics that do involve a change in a sample’s chemical makeup. Example : rusting of iron is a chemical property cause iron combines with oxygen and moisture from the air to give the new subtance

Physical and Chemical Properties

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Some Example of Physical and chemical properties

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