Chemistry Essentials For Dummies

John T. Moore

• Publisher: For Dummies
• Year: 2019
• ISBN:
  9781119591115
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Chemistry
• Index: Chemistry

Chemistry Essentials For Dummies (9781119591146) was previously published as Chemistry Essentials For Dummies (9780470618363). While this version features a new Dummies cover and design, the content is the same as the prior release and should not be considered a new or updated product.

Whether studying chemistry as part of a degree requirement or as part of a core curriculum, students will find Chemistry Essentials For Dummies to be an invaluable quick reference guide to the fundamentals of this often challenging course. Chemistry Essentials For Dummies contains content focused on key topics only, with discrete explanations of critical concepts taught in a typical two-semester high school chemistry class or a college level Chemistry I course, from bonds and reactions to acids, bases, and the mole. This guide is also a perfect reference for parents who need to review critical chemistry concepts as they help high school students with homework assignments, as well as for adult learners headed back into the classroom who just need to a refresher of the core concepts.

The Essentials For Dummies Series
Dummies is proud to present our new series, The Essentials For Dummies.Now students who are prepping for exams, preparing to study new material, or who just need a refresher can have a concise, easy-to-understand review guide that covers an entire course by concentrating solely on the most important concepts. From algebra and chemistry to grammar and Spanish, our expert authors focus on the skills students most need to succeed in a subject.

Chapter 1

Matter and Energy: Exploring the Stuff of Chemistry

IN THIS CHAPTER

Understanding the states of matter

Differentiating between pure substances and mixtures

Measuring matter with the metric system

Examining the properties of chemical substances

Discovering the different types of energy

Simply put, chemistry is a whole branch of science about matter, which is anything that has mass and occupies space. Chemistry is the study of the composition and properties of matter and the changes it undergoes.

Matter and energy are the two basic components of the universe. Scientists used to believe that these two things were separate and distinct, but now they realize that matter and energy are linked. In an atomic bomb or nuclear reactor, for instance, matter is converted into energy. (Perhaps someday science fiction will become a reality and converting the human body into energy and back in a transporter will be commonplace.)

In this chapter, you examine the different states of matter and what happens when matter goes from one state to another. I show you how to use the SI (metric) system to make matter and energy measurements, and I describe types of energy and how energy is measured.

Knowing the States of Matter and Their Changes

Matter is anything that has mass and occupies space. It can exist in one of three classic states: solid, liquid, and gas. When a substance goes from one state of matter to another, the process is called a change of state, or phase change. Some rather interesting things occur during this process, which I explain in this section.

Solids, liquids, and gases

Particles of matter behave differently depending on whether they’re part of a solid, liquid, or gas. As Figure 1-1 shows, the particles may be organized or clumped, close or spread out. In this section, you look at the solid, liquid, and gaseous states of matter.

FIGURE 1-1: Solid, liquid, and gaseous states of matter.

Solids

At the macroscopic level, the level at which you directly observe with your senses, a solid has a definite shape and occupies a definite volume. Think of an ice cube in a glass — it’s a solid. You can easily weigh the ice cube and measure its volume.

At the microscopic level (where items are so small that people can’t directly observe them), the particles that make up the solid are very close together and aren’t moving around very much (see Figure 1-1a). That’s because in many solids, the particles are pulled into a rigid, organized structure of repeating patterns called a crystal lattice. The particles in the crystal lattice are still moving but barely — it’s more of a slight vibration. Depending on the particles, this crystal lattice may be of different shapes.

Liquids

Unlike solids, liquids have no definite shape; however, they do have a definite volume, just like solids do. The particles in liquids are much farther apart than the particles in solids, and they’re also moving around much more (see Figure 1-1b).

Even though the particles are farther apart, some particles in liquids may still be near each other, clumped together in small groups. The attractive forces among the particles aren’t as strong as they are in solids, which is why liquids don’t have a definite shape. However, these attractive forces are strong enough to keep the substance confined in one large mass — a liquid — instead of going all over the place.

Gases

A gas has no definite shape and no definite volume. In a gas, particles are much farther apart than they are in solids or liquids (see Figure 1-1c), and they’re moving relatively independent of each other. Because of the distance between the particles and the independent motion of each of them, the gas expands to fill the area that contains it (and thus it has no definite shape).

Condensing and freezing

If you cool a gaseous or liquid substance, you can watch the changes of state, or phase changes, that occur. Here are the phase changes that happen as substances lose energy:

• Condensation: When a substance condenses, it goes from a gas to a liquid state. Gas particles have a high amount of energy, but as they’re cooled, that energy decreases. The attractive forces now have a chance to draw the particles closer together, forming a liquid. The particles are now in clumps, as is characteristic of particles in a liquid state.
• Freezing: A substance freezes when it goes from a liquid to a solid. As energy is removed by cooling, the particles in a liquid start to align themselves, and a solid forms. The temperature at which this occurs is called the freezing point (fp) of the substance.

You can summarize the process of water changing from a gas to a solid in this way:

Here, the (l) stands for liquid, the (g) st...

Table of contents

• Cover
• Table of Contents
• Introduction
• Chapter 1: Matter and Energy: Exploring the Stuff of Chemistry
• Chapter 2: What’s in an Atom?
• Chapter 3: The Periodic Table
• Chapter 4: Nuclear Chemistry
• Chapter 5: Ionic Bonding
• Chapter 6: Covalent Bonding
• Chapter 7: Chemical Reactions
• Chapter 8: Electrochemistry: Using Electrons
• Chapter 9: Measuring Substances with the Mole
• Chapter 10: A Salute to Solutions
• Chapter 11: Acids and Bases
• Chapter 12: Clearing the Air on Gases
• Chapter 13: Ten Serendipitous Discoveries in Chemistry
• Index
• About the Author
• Connect with Dummies
• End User License Agreement