Easy Chemistry Step-by-Step

By Marian DeWane

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Easy Step-by-Step, the quickest route to learning a subject through a solid grounding in the basics

About the Book
What you won’t find in Easy Chemistry Step-by-Step is a lot of endless drills. Instead, you get a clear explanation that breaks down complex concepts into easy-to-understand steps, followed by highly focused exercises that are linked to core skills--enabling learners to grasp when and how to apply those techniques.

Key Selling Features

• Large step-by-step charts breaking down each step within a process and showing clear connections between topics and annotations to clarify difficulties
• Stay-in-step panels show how to cope with variations to the core steps
• Step-it-up exercises link practice to the core steps already presented
• Missteps and stumbles highlight common errors to avoid
• Successful series format in foreign languages (130,000 copies sold)--now extended to popular study categories: math, science, English grammar
• Strong graphic elements emphasize step-by-step processes and connections between topics
• Clear explanations and annotations explain complex concepts in everyday language

Market/Audience
For beginners who need help with grasping the core concepts of chemistry, and for more advanced learners who want to review or firm up the basics.

About the Author
Marian DeWane (Boise, ID)

• Language: English
• Publisher: McGraw-Hill Education
• Release date: Jun 27, 2014
• ISBN: 9780071767897

Book preview

Index

Preface

Chemistry is a fascinating subject, but with all the material to be covered in any chemistry course it can be overwhelming. There are several types of chemistry—inorganic chemistry, biochemistry, and organic chemistry, for example—but all have a similar foundation. Easy Chemistry Step-by-Step allows you to move at your own pace through basic chemistry concepts. Some concepts will be easier than others to master.

Each chapter begins with a foundation section that provides an introduction to the topic. This is followed by further, in-depth explanations. Step-by-step problem-solving strategies are provided to help build a solid foundation of chemical concepts. These strategies include questions to ask yourself while performing a skill and then examples for you to solve. Common mistakes are pointed out as missteps to be aware of. The in-depth examples are followed by guided practice and exercises to try on your own. Although the chapters build on each other, they also stand alone so you can return to any particular concept and review it as needed.

Learning chemistry is similar to learning a foreign language. You will learn the language of several types of compounds and their different naming systems. A solid foundation is important as you continue to take additional courses. Understanding the fundamentals of chemistry also requires knowledge of mathematics and how the mathematics relate to chemical concepts. The goal of Easy Chemistry Step-by-Step is to provide the necessary foundation in chemical concepts and the mathematics of chemistry for you to be successful in your first chemistry course.

1

The Elements on the Periodic Table

Elements and compounds have names. The names vary by language but the symbol and formula of the element or compound remain the same and are controlled by an international committee (IUPAC). Some examples include magnesio in Spanish, which is magnesium in English, yet both are the symbol Mg; argento in Italian, plata in Spanish, and silver in English all have the symbol Ag; and crypto in Italian and krypton in English both have the symbol Kr. To learn chemistry, you must first know the chemistry language of the elements!

Element Names and Location on the Periodic Table

The periodic table shows the arrangement of the elements. Learning the symbols and their names will take practice. For many elements, the name and symbol are easy to learn because the name and symbol are similar to each other. There is no reasoning to finding an element on the periodic table, such as going in alphabetical order.

One way to help find an element is to know if the element is a metal or nonmetal. Metals are on the left of the table on the next page and nonmetals are on the far right.

Questions to Ask Yourself

Step 1. Is the element or symbol a metal? Remember to look on the left-hand side of the table.

Step 2. Is the element or symbol a nonmetal? Remember to look on the right-hand side of the table.

Problems It is important to know the names and symbols before trying to name compounds. Find the following elements on the periodic table and give their symbols.

a. calcium

b. zinc

c. fluorine

d. tin

e. iron

Solutions

a. Calcium is a metal, so look on the left-hand side. It is in the second column, the third one down, and has the symbol Ca.

b. Zinc is a metal, so it is on the left-hand side. Looking, we find it toward the middle in the fourth row and it has the symbol Zn.

c. Fluorine in a nonmetal and is found on the right-hand side in the next-to-last column. It has the symbol F.

d. Tin is a metal, so first look on the left-hand side. Looking, we find it toward the middle right in the fifth row;it has the symbol Sn.

e. Iron is a metal so it is on the left-hand side. Looking, we find it toward the middle in the fourth row;it has the symbol Fe.

On Your Own: Exercise 1.1

Give the symbols of the following elements.

1. cobalt

2. copper

3. neon

4. lithium

5. sulfur

It is also important to be able to convert the name of an element to its symbol. The same steps are used.

Step 1. Is the element or symbol a metal? Remember to look on the left-hand side of the table.

Step 2. Is the element or symbol a nonmetal? Remember, look on the right-hand side of the table.

Problems Give the names of the elements represented by the following symbols.

a. Cd

b. Mn

c. K

d. P

e. Si

Solutions

a. Cd is a metal, so start looking on the on the left-hand side. Looking, we find it toward the middle right in the fifth row; it has the name cadmium.

b. Mn is a metal, so start looking on the on the left-hand side. Looking, we find it toward the middle of the table in the fourth row; it has the name manganese.

c. K is a metal, so start looking on the on the left-hand side. Looking, we find it in the in the first column; it has the name potassium.

d. P is a nonmetal, so start looking on the on the right-hand side. Looking, we find it toward the middle right in the fourth row; it has the name phosphorus.

e. Si is a metalloid or semimetal, so start looking on the on the right-hand side of the table. Looking, we find it toward the middle right in the third row; it has the name silicon.

On Your Own: Exercise 1.2

Give the names of the elements represented by the following symbols.

1. Cl

2. Al

3. Cr

4. U

5. Pb

Origins of Element Names

The symbols of the elements are derived from a variety of sources, which makes it harder to know all the elements. Some are from the Latin name of the element, some from the Greek, and some are from the place where it was discovered, and yet others may be named for their discoverer. Sources of some of the names are easy to recognize, while others are not. Knowing the story behind the name can help you remember the symbol. You may have to research the origins of the names.

Questions to Ask Yourself

Step 1. Does the beginning of an element name refer to a person or place you might know?

Step 2. Are the symbol and name greatly different so that you can’t tell? If this is the case, most likely it is an element known for a long period of time or the name has a reference in another language.

Problems Look at the names of the elements on the chart and answer the following questions.

a. What place does element 98, Cf, refer to?

b. What person does element 99, Es, refer to?

c. What were elements 50 and 82 named after?

Solutions

a. Element 98 is californium and refers to the state of California, the state in which this element was discovered.

b. Element 99 is einsteinium and refers to the scientist Albert Einstein.

c. There is no reference and the name and symbol are very different. Element 50 is tin, which has the symbol Sn. The symbol comes from stannous, it’s old name. Element 82 is lead, which has the symbol Pb. The symbol comes from its old name of plumbum and was known as the plumber’s metal due to its use in pipes.

On Your Own: Exercise 1.3

Look at the names of the elements on the periodic chart and answer the following questions.

1. What places do elements 63, 95, and 97 refer to?

2. What scientists were elements 100, 101, and 102 named after?

3. What were elements 79 and 80 named after?

Types of Elements

The elements can be divided into metals, nonmetals, and semimetals (also called metalloids). Identifying the category is important when compounds are named. The number of elements is increasing slowly as more elements are found but currently the number is 118. The recently discovered elements all live for only a very short time before undergoing radioactive decay.

Notice that the table rows and columns on the periodic table have numbers. The rows are called periods. The columns are called families or groups.

Guided Practice in Determining the Element Types

Do you notice a trend in the location of metals, nonmetals, and semimetals? Understanding the trend will help to identify an element as a metal, nonmetal, or semimetal. Knowing where an element is located on the periodic table is important in chemistry. On the following blank periodic table, differentiate metals from nonmetals and semimetals.

Questions to Ask Yourself

Step 1. Where is the element on the periodic table?

Step 2. What is the period (row) number of the element?

Step 3. What is the column number of the element?

Step 4. Is the element from the metals, nonmetals, or semimetals section?

Problems Identify the period and column of the element and identify it as a metal, nonmetal, or semimetal.

a. Chlorine

b. Cadmium

c. Arsenic

Solutions

a. On the periodic table, the element chlorine is located in period 3 and column 17. This is in the area where nonmetals are found. Chlorine is a yellow-green colored gas.

b. Cadmium is in period 5 and column 12. This is the region of the metals. It is a silver-colored metal.

c. On the periodic table arsenic is in period 4 and column 15. This is in the semimetals or metalloids region.

On Your Own: Exercise 1.4

Identify the period, column, and whether the element is a metal, nonmetal, or metalloid.

1. Antimony

2. Titanium

3. Cesium

4. Xenon

5. Iodine

Element Phases

The periodic table phase information is based on the conditions of 1 atmosphere of pressure and 25°C. At these conditions, some elements occur as solids, some as liquids, and some as gases. Only two elements are found naturally as liquids at 25°C: mercury and bromine. Look at the following table with phases identified. (Note: Not all versions of the periodic table will identify phases.)

Problem On the following blank periodic table, indicate where the solids, liquids, and gases are found. Look at the tables of metals, semimetals, and nonmetals and the table of the phases. Generally, what is the correlation between the two?

Solution

The metals and semimetals are solid with the exception of mercury, which is a liquid. The nonmetals vary between solid, liquid, and gas but are mostly gases.

Diatomic Elements

Some elements do not normally occur as a single atom but are bound to another atom in pairs. These atoms are said to be diatomic elements (diatomic means two atoms). On the periodic table, these elements end in the letters -gen or -ine. A way to help remember is that there are seven of them and with the exception of hydrogen, they begin at element seven and form a 7 on the periodic table.

The elemental molecular formulas of these diatomic elements are designated with the subscript 2 after their symbol. When a question is asked about the nitrogen atom, it is asking about N, but if the question is about the element nitrogen, the formula is N2.

Problem On the following table, indicate the location of the diatomic elements.

Solution

Questions to Ask Yourself

Step 1. Does the element end in the letters -gen or -ine?

Step 2. If yes, add a subscript 2 after the symbol. If no, a subscript is not added.

Problem Give the names and symbols of elements 7, 18, and 35.

Solution

Nitrogen is element 7 and ends in the letters -gen, so the symbol is N2. Element 18 is argon and does not end in the letters -gen or -ine, so it’s symbol is Ar. Element 53 is bromine, which ends in the letters -ine, so the symbol is Br2.

On Your Own: Exercise 1.5

Give the names and symbols of the elements identified.

1. 1

2. 9

3. 13

4. 53

Review

Identify where the metals, nonmetals, and semimetals are found on the periodic table.

Identify which elements are found as solids, liquids, and gases at standard conditions.

Give the names and symbols of the common elements.

Identify and give the symbols of the diatomic elements.

2

Atomic Structure and Atomic Mass

The three main particles in the atom are protons, neutrons, and electrons. The protons and neutrons are found in the nucleus and are collectively called nucleons. Both nucleons have a mass of approximately 1 amu which stands for atomic mass unit, though the neutron has a slightly larger mass than the proton. An atomic mass unit is equal to 1.66056 × 10–27 kilograms, the SI unit of mass, or 1.66056 × 10–24 grams. Grams are the mass unit we actually measure on a balance scale. The protons, neutrons, and electrons are made up of smaller units, but these are not the focus of this book.

Proton Number

Atoms of the same element all have the same number of protons, which is called the atomic number. On the periodic table, each element has a symbol and an atomic number. The atomic number is also represented by the symbol Z. For instance, copper is atomic number 29 because every atom of copper has 29 protons.

Questions to Ask Yourself

Step 1. What is the symbol of the atom?

Step 2. What is the atomic number, Z, on the periodic table for the atom?

Step 3. How many protons are in the atom?

Problems

a. How many protons are in an atom of carbon?

b. How many protons are in an atom of arsenic?

c. How many protons are in an atom of magnesium?

Solutions

a. 6

Step 1. Find the symbol of the atom. C

Step 2. Determine the atomic number, Z, on the periodic table for the atom. 6

Step 3. Thus, there are 6 protons in the atom.

b. 33

Step 1. Find the symbol of the atom. As

Step 2. Determine the atomic number, Z, on the periodic table for the atom. 33

Step 3. Thus, there are 33 protons in the atom.

c. 12

Step 1. Find the symbol of the atom. Mg

Step 2. Determine the atomic number, Z, on the periodic table for the atom. 12

Step 3. Thus, there are 12 protons are in the atom.

Guided Practice in Determining Proton Numbers

1. How many protons are in an atom of iron?

Step 1.

Step 2. What is the atomic number, Z, on the periodic table for the atom?

Step 3.

2. How many protons are in an atom of cadmium?

Step 1.

Step 2. What is the atomic number, Z, on the periodic table for the atom?

Step 3.

3. How many protons are in an atom of fluorine?

Step 1.

Step 2. What is the atomic number, Z, on the periodic table for the atom?

Step 3.

On Your Own: Exercise 2.1

1. How many protons are in an atom of zinc?

2. How many protons are in an atom of argon?

Electron Number

Another particle in the atom is the electron. Electrons have an approximate mass of 0.00054 amu. In comparison to the proton, the electron mass is so small it does not change the mass of the atom. A hydrogen atom with 1 proton and 1 electron would amount to 1 amu + 0.00054 amu = 1 amu. Thus, electrons do not account for much of the mass. The actual mass listed in tables of a hydrogen atom is 1.007825 amu. This is because there is more than one type of hydrogen atom and the mass on the periodic table is an average of them. This will be explained in detail in the section on isotopes.

A proton has a charge of +1 and an electron has a charge of –1. Atoms do not normally carry a charge, so the number of electrons and protons they contain must be equal. For instance, the copper atom has atomic number 29, so it has 29 protons. This means it also has 29 electrons: 29 + (–29) = 0. If the atom is an ion (i.e., it carries a charge), the number of protons and electrons are not equal. If the ion has a positive charge (called a cation), it has fewer electrons than protons. The sum of protons and electrons will equal the charge: proton # + (–electron #) = charge. If the electron number is given the value x, then we can write an equation:

p + (–x) = charge

For example, Mg²+ (magnesium) has atomic number 12 and therefore has 12 protons. Since the charge is +2, then 12 + (–x) = +2. The number of electrons must be 10: 12 + (–10) = +2. The number of electrons in a negatively charged ion (called an anion) must be greater than the atomic number. For O²–, oxygen, the atomic number is 8, so it has 8 protons. Because the charge is –2, 12 + (–x) = –2. The number of electrons must therefore be 10: 8 + (–10) = –2.

By tradition, when writing a number like minus 2 (–2) as a charge of an ion after a symbol, we write 2– as a superscript. The way to write sulfur with a –2 charge is S²–.

Questions to Ask Yourself

Step 1. What is the atomic number of the atom?

Step 2. How many protons are present?

Step 3. What is the charge of the atom or ion?

Step 4. What is the formula to solve for the number of electrons?

Step 5. How many electrons are present?

Problems

a. How many electrons are in an atom of calcium?

b. How many electrons are in the cation Ca²+?

c. How many electrons are in the anion P³–?

Solutions

a. 20

Step 1. Find the atomic number of the atom. 20

Step 2. Determine how many protons are present. 20

Step 3. Identify the charge of the atom or ion. 0

Step 4. Use the formula to solve for the number of electrons. 20 + (–x) = 0

Step 5. There are 20 electrons present.

b. 18

Step 1. Find the atomic number of the atom. 20

Step 2. Determine how many protons are present. 20

Step 3. Identify the charge of the atom or ion. 2+

Step 4. Use the formula to solve for the number of electrons. 20 + (–x) = +2

Step 5. There are 18 electrons present.

c. 18

Step 1. Find the atomic number of the atom. 15

Step 2. Determine how many protons are present. 15

Step 3. Identify the charge of the atom or ion. –3

Step 4. Use the formula to solve for the number of electrons. 15 + (–x) = –3

Step 5. There are 18 electrons present.

Guided Practice in Determining Electron Numbers

1. How many electrons are in an atom of potassium?

Step 1.

Step 2.

Step 3.

Step 4. What is the formula to solve for the number of electrons?

Step 5.

2. How many electrons are in the ion sulfide, S²- ?

Step 1.

Step 2.

Step 3.

Step 4. What is the formula to solve for the number of electrons?

Step 5.

3. How many electrons are in the cation Cr⁶+?

Step 1.

Step 2.

Step 3.

Step 4. What is the formula to solve for the number of electrons?

Step 5.

4. How many electrons are in an atom of krypton?

Step 1.

Step 2.

Step 3.

Step 4. What is the formula to solve for the number of electrons?

Step 5.

5. How many electrons are in the anion carbide, C⁴–?

Step 1.

Step 2.

Step 3.

Step 4. What is the formula to solve for the number of electrons?

Step 5.

On Your Own: Exercise 2.2

1. How many electrons are in the anion iodide, I–?

2. How many electrons are in the cation Mn⁷+?

3. How many electrons are in an atom of tungsten?

4. How many electrons are in the anion oxide, O²-?

5. How many