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Chemistry I
Chapter 4 The Periodic Table
Homework Assignments:
Section 1 pgs. 116-122 Answer 1-13.
Section 2 pgs. 123-131 Answer 1-9.
Section 3 pgs. 132-141 Answer 1-13.
Section 4 pgs. 142-147 Answer 1-8.
FCAT Prep pgs. 154,155. Answer 1-4, 7, 8, 10.
Before you read chapter 4 answer the following two questions based on your prior
knowledge! Answer these questions in complete sentences. Do not answer with a single
word or phrase.
1. Define element.
2. What is the relationship between the number of protons and the number of electrons
in a neutral atom?
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Section 1: Patterns in Element Properties pgs. 116-122.
Objectives:
1. Describe the historical development of the periodic table.
2. Describe the organization of the modern periodic table according to the periodic law.
Vocabulary - Define the following.
periodic law--
valence electrons--
group--
period--
Notes:
Patterns in Element Properties
Misconceptions: Many people think that because certain elements have similar chemical
properties, they have similar physical properties. This is not the case. For instance
chlorine is a yellow green gas while bromine is a reddish brown liquid. However ele-
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ments in a group do share certain chemical properties. All the elements in the chlorine
and bromine group (same column) are poisonous and all tend to gain one electron.
History
In 1865 John Newlands arranged the known elements in a table according to their properties and increasing atomic mass. He noted that elements in a row had similar chemical
and physical properties that repeated every eight elements which he called the law of octaves.
In 1869 Dmitri Mendeleev improved upon Newland's work. There were many gaps in his
periodic table. From these gaps Mendeleev predicted the existence of several elements
and their properties. He is credited with the invention of the first true periodic table.
Like Newland he placed the elements in rows by increasing atomic mass.
Henry Moseley in the early 1900s created the first modern periodic table based on increasing atomic number.
Mendeleev's principle of chemical periodicity is today called the periodic law which
states that the physical and chemical properties of the elements are periodic functions of
their atomic numbers.
Organization of the Periodic Table
Vertical columns are called groups (18). Elements in a similar group have similar properties. This is because they have similar electron configurations.
Rows are called periods (7).
Elements in each column have the same number of outer electrons called valence electrons.
Some periodic tables, such as the one on pgs.120-121, show an electron configuration for
each element. Bromine for instance has the short hand electron configuration of
[Ar]3d104s24p5. The largest coefficient in this electron configuration is 4, which indicates
the period or row in which the element is located. As you will recall the largest coefficient is called the principal quantum number.
The column can also be determined by looking at the last lower case letter and its superscript, in bromine's case this is p5. The periodic tables on p. 119,120, and 121 shows that
any p5 is in group #17.
Answer the following questions to test your knowledge of section 1.
1. What do the electron configurations of lithium and sodium have in common?
2. What do the electron configurations of fluorine and chlorine have in common?
3. Mendeleev arranged the elements in the periodic table according to what property?
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4. Write the symbols and atomic numbers for silver, radon, and zinc.
Symbol
Atomic Number
silver =
radon =
zinc =
5. What is another name for a row in the periodic table?
6. What is another name for a column in the periodic table?
7. What is the name given to the outermost electrons in an atom?
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Section 2: pgs. 124-131. Tour of the Periodic Table
Objectives:
1. Locate the different families of the main-group elements on the periodic table.
2. Describe their characteristic properties.
3. Relate their properties to their electron configuration (for example, the group 1 elements are highly reactive metals because they have only one outer electron).
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Vocabulary: Define the following.
main-group element-alkali metal--
alkaline-earth metal--
halogen--
noble gas--
transition metal--
lanthanide--
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actinide--
alloy--
The Periodic Table
Groups also known as families are arranged in 18 vertical columns.
The horizontal rows are called periods.
There are three different forms of labeling columns in Europe and America, of which we
will use two. The older of these two systems uses a Roman numeral with either an A or a
B. The IUPAC system, (The International Union of Pure and Applied Chemistry) labels
columns with the numerals 1 to 18.
The main-group elements also called the representative elements occupy columns 1,2, 1318 and contain 4 groups (groups 1,2,17,18) with additional special names.
Group 1 is called the alkali metals.
Group 2 is called the alkaline earth metals.
Group 17 is called the halogens.
Group 18 is called the noble gases.
Groups 3-13 are called the transition metals
The two displaced row separated from the periodic table at the bottom are called the inner transition metals or the lanthanides and actinides.
Hydrogen is separated from the rest of the elements in the periodic table because of its
unique properties. Though hydrogen by its position in the periodic table may appear to
be a metal it more closely resembles the nonmetal halogens.
Metals, Nonmetals, and Semimetals (Metalloids)
Metals--have luster or shine, are good conductors of heat and electricity, are solids at
room temperature (exception liquid mercury), are malleable, and ductile. Metals make
up most of the elements of earth and are located on the left and center of the periodic table.
Nonmetals--do not have luster, are poor conductors of heat and electricity, are not malleable or ductile, and many are gases at room temperature, though some are solids,
(bromine is an exception and exists as a liquid at room temperature). Nonmetals are located on the right side of the periodic table.
Semimetals (Metalloids)--These elements share properties of metals and nonmetals.
There are only a few metalloids, which will be given to you to mark on your periodic table.
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Electron Configuration and the Periodic Table
The highest energy electrons are in the outermost level. These electrons are the s and p
sublevel electrons and are called valence electrons.
*****It is the valence electrons that give an element its chemical properties.
****The periodic table is arranged in such a way so that the elements in a group have
similar properties because they have valence electrons in a similar configuration.
The s,p,d, and f block Elements
The s and p block elements are called the main-group or representative elements. These
are columns 1,2 13-18.
The s-block Elements (columns 1,2)
The s-block elements are hydrogen and helium and Group IA (column 1) and IIA elements (column 2). The s-block elements can hold only a maximum of 2 electrons.
The p-block Elements (columns 13-18)
The p-block elements are those elements found in Group IIIA (columns 13-18) to Group
VIIIA. The p-block elements can hold only a maximum of 6 electrons.
The d-block Elements (columns 3-12)
The d-block elements are located in the middle of the periodic table. These are the
Group B elements. The d-block elements can hold only a maximum of 10 electrons.
The f-block Elements
The f-block elements are the 28 elements found in the 2 rows separated from the bottom
of the periodic table. The f-block elements can hold a maximum of 14 electrons.
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The s and p elements are called the main-group or representative elements.
The d elements are called the transition metals.
The f elements are called the inner transition elements or the lanthanides and actinides.
Answer the following in your notes here.
Describe the properties of:
Group 1 Alkali metals--
Group 2 Alkaline metals--
Groups 3-12 Transition metals--
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Group 17 Halogens--
Group 18 Noble Gases--
Lanthanides--
Actinides--
Answer the following questions.
1. What is malleability?
2. What is ductility?
3. What groups make up the main group elements?
4. How are alkali metals stored?
5. If an element is found in nature in its pure state, what can you infer about its chemi
cal reactivity?
6. What sublevel (s, p, d, or, f) is filled in by the transition metals?
7. What sublevel is filled by lanthanides?
8. What is the most reactive metal group?
9. What gives an element its chemical properties?
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Section 3 pgs. 132-141. Trends in the Periodic Table
Objectives:
1. Describe periodic trends in ionization energy, and relate them to the atomic structures of the elements.
2. Describe periodic trends in atomic radius, and relate them to the atomic structures of
the elements.
3. Describe periodic trends in electronegativity, and relate them to the atomic structures
of the elements.
4. Describe periodic trends in ionic size, electron affinity, melting and boiling points,
and relate them to the atomic structures of the elements.
Vocabulary Define the following:
trend--
ionization energy--
electron shielding--
bond radius--
electronegativity--
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Notes:
Ionization Energy -- The energy required to remove an electron.
Decreases as you move down a group due to electron shielding.
Increases as you move across a period.
Atomic Radius-- Since the volume of an atom depends on the position of its outer electrons which have no definite border the atomic radius is difficult to measure. The radius
therefore depends on bond radius, which is the distance between the nuclei of two
bonded atoms divided by two. Atomic radius:
Increases as you move down a group.
Decreases as you move across a period.
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Electronegativity-- This is a scale to show how strongly an atom attracts electrons when
bonded to another atom. Electronegativity:
Decreases as you move down a group.
Increases as you move across a period.
Ionic Radius The size of an ion. Ionic radius follows the same trend as atomic radius.
Electron Affinity The energy change that occurs when an atom is not bonded and gains
an electron. This is similar to electronegativity and follows the same trends.
Melting and boiling points are not consistent and across a period, they may increase,
then decrease, then repeat this pattern. This is why we are not discussing them to any
extent in this chapter.
Answer the following questions.
1. What is meant by periodic trend?
2. Which of the trends mentioned in this section generally and steadily increase as you
go from left to right and bottom to top on the periodic table except for noble gases?
3. Which has the greater electronegativity, oxygen or nitrogen?
4. With the exception of the noble gases, why is an element with a high ionization energy
likely to have high electron affinity?
5. Which element is the most reactive alkali metal?
6. Which element is the most reactive halogen?
Section 4 pgs. 142-147. Where Did the Elements Come From?
Objectives:
1. Describe how the naturally occurring elements form.
2. Explain how a transmutation changes one element into another.
3. Describe how particle accelerators are used to create synthetic elements.
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Vocabulary: Define the following.
nuclear reaction--
superheavy element--
transmutation--
Natural Elements
Most of the elements were formed in the big bang. After the big bang temperatures were
so high that matter could not exist. It was only after the universe expanded and cooled,
that electrons, protons, and neutrons were formed.
Most of the matter of the universe is hydrogen. As gravity pulled regions of hydrogen
together, the pressure caused temperatures to increased allowing nuclear reactions to
occur. Nuclear fusion reactions change hydrogen to helium.
As temperatures increase helium atoms could begin to fuse producing heavier elements.
Eventually very dense stars could produce elements as large as iron.
Some of these massive stars eventually became supernovas. In the intense heat of the
supernova, elements heavier than iron formed and all were thrust out into space.
Over time some of these gases and heavier elements coalesced into our solar system.
Transmutations
Transmutations occur when one element changes into another. This does not happen in
ordinary chemical reactions.
There are 93 naturally occurring elements. It has become possible to make other elements in high tech labs using particle accelerators such as cyclotrons and synchrotrons.
As the name suggests these types of equipment accelerate particles to high speeds and
then have them collide with stationary particles. In the collisions new elements or synthetic elements are formed.
Synthetic elements larger than uranium and are also called superheavy elements.
Answer the following questions.
1. What is the big bang?
2. Why isn’t fusion an energy source on earth?
3. What is the heaviest element formed during normal fusion (not supernova) in stars?
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4. Why is so little known about the properties of superheavy elements?