Topic 1 Topic 1 Topic 1: Chemistry and Matter Table of Contents Basic Concepts Additional Concepts

Chemistry is the science that investigates and explains the structure and properties of matter. Composition, Structure, and Behavior Chemistry and Matter: Basic Concepts Matter is the stuff that’s all around you: the metal and plastic of a telephone, the paper and ink of a book, the glass and liquid of a bottle of soda, the air you breathe, and the materials that make up your body. A more formal definition of matter is anything that takes up space and has mass. Topic 1 Topic 1

Composition, Structure, and Behavior The properties of matter describe the characteristics and behavior of matter, including the changes that matter undergoes. Topic 1 Topic 1 Chemistry and Matter: Basic Concepts

Matter that is large enough to be seen is called macroscopic, so all of your observations in chemistry, and everywhere else, start from this perspective. Macroscopic View of Matter You may get hints of the actual structure from a macroscopic view. You must go to a submicroscopic perspective to understand how the hidden structure of matter influences its behavior. Topic 1 Topic 1 Chemistry and Matter: Basic Concepts

The submicroscopic view gives you a glimpse into the world of atoms. Submicroscopic View of Matter It is a world so small that you cannot see it even with the most powerful microscope, hence the term submicroscopic. You learned in earlier science courses that matter is made up of atoms. Topic 1 Topic 1 Chemistry and Matter: Basic Concepts

A powerful way to classify matter is by its composition. This is the broadest type of classification. Classification by Composition A qualitative observation is one that can be made without measurement. When you examine an unknown piece of stuff, you first ask, “What is it made of?” Sucrose is composed of the elements carbon, hydrogen, and oxygen. This is a qualitative expression of composition. Topic 1 Topic 1 Chemistry and Matter: Basic Concepts

After a qualitative analysis, the next question that you might ask is how much of each of the elements is present. Classification by Composition A quantitative observation is one that uses measurement. For sucrose, the answer to that question is that 100 g of sucrose contains 42.1 g of carbon, 51.4 g of oxygen, and 6.5 g of hydrogen. This is a quantitative expression of composition. Topic 1 Topic 1 Chemistry and Matter: Basic Concepts

Pure substance or a mixture? Topic 1 Topic 1 Chemistry and Matter: Basic Concepts A substance is matter, either an element or compound, with the same fixed composition and properties. A sample of matter is either pure—made up of only one kind of matter— or it is a mixture of different kinds of matter.

A mixture is a combination of two or more substances in which the basic identity of each substance is not changed. Unlike pure substances, mixtures do not have specific compositions. Topic 1 Topic 1 Chemistry and Matter: Basic Concepts Pure substance or a mixture?

A physical change is a change in matter that does not involve a change in the chemical identity of individual substances. Examples of physical changes include: boiling, freezing, melting, evaporating, dissolving, and crystallizing. Topic 1 Topic 1 Chemistry and Matter: Basic Concepts Pure substance or a mixture?

Physical properties are characteristics that a sample of matter exhibits without any change in its identity. Topic 1 Topic 1 Chemistry and Matter: Basic Concepts Pure substance or a mixture?

Examples of the physical properties of a chunk of matter include its: solubility, melting point, boiling point, color, density, electrical conductivity, and physical state (solid, liquid, or gas). Topic 1 Topic 1 Chemistry and Matter: Basic Concepts Pure substance or a mixture?

A heterogeneous mixture is one with different compositions, depending upon where you look. The components of the mixture exist as distinct regions, often called phases. Topic 1 Topic 1 Chemistry and Matter: Basic Concepts Pure substance or a mixture?

Homogeneous mixtures are the same throughout. Another name for a homogeneous mixture is solution. Topic 1 Topic 1 Chemistry and Matter: Basic Concepts Pure substance or a mixture? Some solutions are gases. Air, for example, is a homogeneous mixture of several gases. Some solutions are solid. Liquid solutions do not have to be liquid or contain water.

Many of the solutions you encounter are aqueous solutions, for example, soda, tea, contact-lens cleaner, and other clear cleaning liquids. In addition, most of the processes of life occur in aqueous solutions. Topic 1 Topic 1 Chemistry and Matter: Basic Concepts Pure substance or a mixture?

Topic 1 Topic 1 Chemistry and Matter: Basic Concepts Pure substance or a mixture?

Two Types of Substances One type of pure substance can be broken down into simpler substances. This type of substance is called a compound. Another type of substance cannot be broken down into simpler substances. Such a substance is called an element. Topic 1 Topic 1 Chemistry and Matter: Basic Concepts All the substances of the universe are either elements, compounds formed from elements, or mixtures of elements and compounds.

Two Types of Substances Of the known elements, only about 90 occur naturally on Earth. The remainder are synthesized, usually in barely detectable amounts, in high-energy nuclear experiments. Less than half of the 90 naturally occurring elements are abundant enough to play a significant role in the chemistry of everyday stuff. Topic 1 Topic 1 Chemistry and Matter: Basic Concepts

Organizing the Elements The periodic table organizes elements in a way that provides a wealth of chemical information—much more than is evident to you now. It shows the chemical symbols for the elements. Their symbols usually correspond to their names in Latin. Topic 1 Topic 1 Chemistry and Matter: Basic Concepts

Periodic Table of the Elements Topic 1 Topic 1 Chemistry and Matter: Basic Concepts

Compounds Are More Than One Element A more complete definition is that a compound is a chemical combination of two or more different elements joined together in a fixed proportion with a unique set of chemical and physical properties. Topic 1 Topic 1 Chemistry and Matter: Basic Concepts More than 10 million compounds are known and the number keeps growing.

Compounds Are More Than One Element Topic 1 Topic 1 Chemistry and Matter: Basic Concepts Some new compounds are discovered and isolated from natural chemical sources such as plants and colonies of bacteria and are synthesized in laboratories for many different uses.

Compounds Are More Than One Element The properties of the compound are different from the properties of the elements that compose the compound. Topic 1 Topic 1 Chemistry and Matter: Basic Concepts silver + bromine = silver bromide

Compounds Are More Than One Element A formula is a combination of the chemical symbols that show what elements make up a compound and the number of atoms of each element. CompoundFormula CaffeineC 8 H 10 N 4 O 2 Topic 1 Topic 1 Chemistry and Matter: Basic Concepts

Compounds Are More Than One Element Formulas provide a shorthand way of describing a submicroscopic view of a compound. You probably already use formulas like H 2 O and CO 2 as a way of talking about water and carbon dioxide. Topic 1 Topic 1 Chemistry and Matter: Basic Concepts

Chemical Properties Chemical properties are those that can be observed only when there is a change in the composition of the substance. Topic 1 Topic 1 Chemistry and Matter: Basic Concepts Rusting is a chemical reaction in which iron combines with oxygen to form a new substance, iron oxide. Inability to react is also a chemical property.

Chemical Changes chemical change, the change of one or more substances into other substances. A chemical property always relates to a Another term for chemical change is chemical reaction. Topic 1 Topic 1 Chemistry and Matter: Basic Concepts

Chemical Changes Topic 1 Topic 1 Chemistry and Matter: Basic Concepts Click box to view movie clip.

Chemical Changes All matter is made of atoms, and any chemical change involves only a rearrangement of the atoms. Atoms do not just appear. Atoms do not just disappear. This is an example of the law of conservation of mass, which says that in a chemical change, matter is neither created nor destroyed. It would be equally correct to call this the law of conservation of matter. Topic 1 Topic 1 Chemistry and Matter: Basic Concepts

Basic Assessment Questions Question 1 Identify each of the following as either a compound or a mixture. A. sand B. water C. juice Topic 1 Topic 1

Basic Assessment Questions Answers A. sand B. water C. juice mixture compound mixture Topic 1 Topic 1

Basic Assessment Questions Classify each of the following as a chemical or physical property. Question 2 A. density B. reactivity C. color D. melting point Topic 1 Topic 1

Basic Assessment Questions Answers A. density B. reactivity C. color D. melting point physical property chemical property physical property Topic 1 Topic 1