# Things You Need to Know Before You Study Chemistry

it's always a good idea to know what it is that you are going to learn, so the frst question to answer is what is Chemistry?

## Chemistry

The definition that we will use is that *Chemistry is the study of matter, the reactions and interactions of matter and the energy associated with those reactions and interactions*. This is a good working definition and will be used to define the direction that this text will take. However this definition is useless if you don’t understand what it all means.

Let’s break it down. Here is that definition again, but with each word that requires explanation set as a link to a page that discusses it. *Chemistry is the study of matter, the reactions and interactions of matter and the energy associated with those reactions and interactions*.

## A little bit of Physics

To understand everything in this text, you will also need to know a little bit of physics. Specifically, you need to understand force and charge.

To work within chemistry we will be making and discussing measurements and for that reason, you need to undestand...

## The Metric System

The Metric system is the measurement system used by people in virtually every nation of the world except the United States. Even within the United States, scientists use the metric system almost exclusively and we will use it for all measurements in chemistry. That means you will not be measuring length in inches, mass in pounds, or volume in gallons or ounces. Since we will be using only the metric system it is not terribly important that you learn any conversions between metric units and their English counterparts, except to get a rough feeling for the size of the basic units.

The metric system is organized into basic units and prefixes, which together can describe anything.

In doing the math for chemistry there are a few basic skills that you must have. Specifically, you must understand scientific notation and you must be able to use the factor label system of problem solving. You will also need to understand density, both as a mathematical concept and as a theoretical concept. Lastly, you may (or may not, depending on your instuctor) need to understand significant figures. All of these things are described below.

## Scientific Notation

Scientific Notation is a way of writing numbers that are either very small or very large in a simple readable fashion. It is described here.

## Factor Label Problem Solving

One of the most important skills you can acquire as you begin a study of chemistry is the abilty to use the factor label method of problem solving. This is also sometimes called dimensional analysis.

## Density

Density is defined as the mass of something divided by its volume, but it is much more than a simple math formula. To understand it, you need to be able to do the math, but also to appreciate what density tells us.

## Significant Figures

Significant Figures is the name given to the system of reading and writing numbers in a way that represents, not only the size of the value, but also the accuracy and reliability of the number. Not all instructors will require you to understand this, so you may not need to look at this material. To understand this idea, you need to understand the idea of reliabilty, the difference between accuracy and precision and then to know what significant figures are, how to count them and how to do math with them.