0-1 What Is Chemistry

I. What is Chemistry ?

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Topic

I.

What is Chemistry ?

Reading Assignment

Integrated Chemistry Today (2nd Ed.), L.H.M Chung, Book 1A, pg 2 – 3, 7

Objectives

0.1 Introduction to Chemistry Scientific investigation

Notes

Introduction to Chemistry Scientists are always curious. The biggest challenge in chemistry is to explain everything that have been observed. For example,

Why does ice melt ? Why does metal conduct electricity but others do not ? Why can paper be burnt into ashes ? Views of chemists (This helps you to understand how chemists view the world.) Chemists look at every question from 3 different aspects : 1. 2. 3.

Macroscopic observation – Observations that can be observed. Microscopic interpretation – Conclusion and explanation arising from logical deduction. Symbolic representation – Symbol and formula representing the macroscopic world and microscopic world.

By knowing the answers of aforementioned questions, the knowledge obtained can be used to develop new technology. The knowledge may also help to make some new materials which have never existed before. Like plastic, it didn’t exist 100 years ago.

I. What is Chemistry ?

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Properties and Changes Or to be more specific, chemistry is a study of the properties of substances. Properties can be divided into 2 main categories : 1. Physical properties - e.g. melting point, boiling point, hardness, taste. 2. Chemical properties - e.g. reactivity of different metals with water. Measurement of a properties is always associated with a change. e.g. In the determination of melting point of ice, it melts into water. e.g. In the determination of the reactivity of sodium with water, sodium turns into a solution in water. A change in which no new substance is formed is called a physical change. e.g. melting of ice. A change in which new substance is formed is called a chemical change. e.g. reaction of sodium with water. In a chemical change, the starting substance is called reactant and the new substance obtained is called product. Reactants Sodium metal + water

→ Product → Sodium hydroxide solution + Hydrogen gas

The change is describe as "sodium metal reacts with water to produce sodium hydroxide solution and hydrogen gas."

Therefore, chemistry may also be considered as 1. an investigation process 2. something that can change the world 3. studying of change 4. CHEM IS TRY

Glossary

macroscopic observation microscopic interpretation formula physical properties chemical properties reactants products

symbolic representation symbol physical change chemical change