## Read to Understand

## Defining Chemistry

Composition, structure, properties, and reactions of matter

- Define the term "chemistry."
- List modern items produced by chemistry.

#### How does soap relate to chemistry?

Chemistry affects every area of our lives. Here is just one example of chemistry in action – the making of soaps. Soap was once made by boiling animal fat in ashes – the product was hard on the skin and not very pleasant to use. Today, soap manufacture involves complicated chemical processes to provide a wide variety of soaps for different skin types. Colors and odors can be custom-made for that individual experience.

### Defining Chemistry

What is this made of? How can we produce this material quicker and at lower cost? Will this product harm us or help us? All of these questions can be answered using the science of chemistry .

#### What Is Chemistry?

If we look up the word “chemistry” in the dictionary, we’ll find something like this: “The science of the composition, structure, properties, and reactions of matter , especially of atomic and molecular systems” (Free Online Dictionary). This definition is certainly accurate, but does not give a good picture of the scope of chemistry or of the many interesting aspects of the field.

Chemistry touches every area of our lives. The medicines we take, the food we eat, the clothes we wear – all these materials and more are, in some way or another, products of chemistry.

#### What Is the World Made Of?

Questions about matter have been asked for centuries. The ancient Greek philosophes spent a lot of time trying to figure out what matter was. Different philosophers debated whether matter was earth, water, air, fire, or some combination. They argued, but did not do any experiments at that time.

It took many centuries for humans to develop a better concept of what matter really is. Even today, we have an incomplete picture of exactly what this stuff is that we can touch and see. Chemistry involves the study of these substances, both in terms of basic properties and also learning all the things we can do with matter.

Chemists look at the world in two ways, often simultaneously. The two worlds of the chemist are the macroscopicworld and the microscopic world. Macroscopic refers to substances and objects that can be seen, touched, and measured directly. Microscopic refers to the small particles that make up all matter. Chemists must observe matter and do experiments macroscopically and then make generalizations and propose explanations that are microscopic in nature. For example, anyone can observe the physical change in appearance that occurs as an iron object such as a tractor that is left out in the elements gradually turns to rust. However, a chemist looks at the rusting tractor and thinks about what is going on with the individual atoms that make up the iron and how they are changing as a result of exposure to oxygen in the air and water from rain. Throughout your study of chemistry, you will often switch back and forth between the macroscopic and microscopic worlds.

Rusting artillery shells.

#### Summary

- Chemistry is the study of matter and the changes it undergoes.
- Chemistry considers both macroscopic and microscopic information.

#### Explore More

1. Read the label on a prepared food product (for example: bread, cereal, dessert). List all the ingredients in the product. Look up each ingredient on the Internet and write down what that material is doing in the food product.
2. Select your favorite hobby or activity. List all the items you use in that activity or hobby. For each item, find out how chemistry has contributed to the creation or better operation of that item.

#### Review

1. How did ancient philosophers study the world around them?
2. What is the macroscopic world?
3. What is the microscopic world?

- chemistry: The study of matter and the changes it undergoes.
- macroscopic: Substances and objects that can be seen, touched, and measured directly.
- matter: Composes all physical objects (what we can touch and see).
- microscopic: The small particles that make up all matter.