Download Chapter 5 The Periodic Table Section 1 Organizing the Elements

Chapter 5 The Periodic Table
CHAPTER OUTLINE
Section 1 Organizing the Elements
Key Idea questions
> How did Mendeleev arrange the elements in his periodic table?
> How are elements arranged in the modern periodic table?
Recognizing a Pattern
> How did Mendeleev arrange the elements in his periodic table?
> In his periodic table, Mendeleev arranged elements in rows by
increasing atomic mass.
• Mendeleev was able to predict new elements.
– Mendeleev left spaces in his table to make the pattern fit.
– He used the spaces to successfully predict the existence and
properties of elements not yet discovered.
• A few elements did not fit the pattern.
Changing the Arrangement
> How are elements arranged in the modern periodic table?
> The modern periodic table organizes elements by atomic number.
When the elements are arranged in this way, elements that have similar
properties appear at regular intervals.
• As scientists learned more about the structure of the atom, they
improved Mendeleev’s table.
• Arranging the table by atomic number (number of protons) rather
than by atomic mass fixed the discrepancies in Mendeleev’s table.
• periodic law: the law that states that the repeating chemical and
physical properties of elements change periodically with the atomic
numbers of the elements
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Super Summary Chapter Outline p. 1
Chapter 5 The Periodic Table
• Elements become less metallic across each period.
– period: a horizontal row of elements in the periodic table
• Elements in a group have similar properties.
– group: a vertical column of elements in the periodic table;
elements in a group share chemical properties
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Super Summary Chapter Outline p. 2
Chapter 5 The Periodic Table
Section 2 Exploring the Periodic Table
Key Idea questions
> Why do elements within a group of the periodic table have similar
chemical properties?
> What happens to an atom that gains or loses electrons?
> What are the three main categories of elements?
The Role of Electrons
> Why do elements within a group of the periodic table have similar
chemical properties?
> The periodic trends in the periodic table are the result of electron
arrangement.
• Valence electrons account for similar properties.
• An element’s location in the periodic table is related to electron
arrangement.
–
Example: Lithium and sodium, in Group 1, each have one valence
electron.
Ion Formation
> What happens to an atom that gains or loses electrons?
> If an atom gains or loses electrons, it no longer has an equal number of
electrons and protons. Because the charges do not cancel completely,
the atom has a net electric charge.
• Group 1 elements form positive ions.
–
The single valence electron is easily removed.
• Group 17 elements form negative ions.
–
The addition of one valence electron fills the outer energy level.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
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Chapter 5 The Periodic Table
How Are Elements Classified?
> What are the three main categories of elements?
> All elements are either metals, nonmetals, or semiconductors.
• Elements in each category have similar properties.
– metal: an element that is shiny and that conducts heat and
electricity well
– nonmetal: an element conducts heat and electricity poorly
– semiconductor (or metalloid): an element or compound that
conducts electric current better than an insulator does but not as
well as a conductor does
Copyright © by Holt, Rinehart and Winston. All rights reserved.
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Chapter 5 The Periodic Table
Section 3 Families of Elements
Key Idea questions
> What does each element family have in common?
> What are the families of metals?
> What are some of the families of nonmetals?
> What are semiconductors?
Classifying Elements Further
> What does each element family have in common?
> In general, the elements in a family have the same number of valence
electrons.
Metals
> What are the families of metals?
> Families of metals include the alkali metals, the alkaline-earth metals,
and the transition metals.
– alkali metal: one of the elements of Group 1 of the periodic table
– alkaline-earth metal: one of the elements of Group 2 of the
periodic table
– transition metal: one of the metals that can use the inner shell
before using the outer shell to bond
• The alkali metals are very reactive.
• Alkaline-earth metals form compounds that are found in limestone
and in the human body.
• Transition metals are in the middle of the periodic table.
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Chapter 5 The Periodic Table
Nonmetals
> What are some of the families of nonmetals?
> Families of nonmetals include the noble gases and the halogens.
– noble gas: one of the elements of Group 18 of the periodic table
– halogen: one of the elements of Group 17 of the periodic table
• The noble gases are relatively inert.
• The halogens combine easily with metals to form salts.
• Nonmetals and their compounds are plentiful on Earth.
Semiconductors
> What are semiconductors?
> As their name suggests, semiconductors are able to conduct heat and
electricity under certain conditions.
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