Chapter 7 Preview Section 1 Arranging the Elements

< Back Next > Preview Main

Chapter 7 The Periodic Table

Preview

Section 1 Arranging the Elements

Section 2 Grouping the Elements

Concept Map


Section 1 Arranging the ElementsChapter 7

Bellringer

Locate the metals on the periodic table. List the names and symbols of five metals that you recognize. Locate the nonmetals on the periodic table. List the names and symbols of five nonmetals that you recognize.

Describe the general positions of the metals and nonmetals on the periodic table. What are the elements that lie between the metals and nonmetals on the periodic table called? Write your responses in your Science Journal.



What You Will Learn

• Elements on the periodic table are arranged in order of increasing number.

• Elements on the periodic table are classified as metals, nonmetals, or metalloids.

• Elements in a horizontal row, or period, are listed in order of increasing atomic number.

• Elements in a vertical column, or group, usually have similar chemical properties.

• The periodic law states that the properties of elements form a pattern according to increasing atomic number.



Discovering a Pattern

• Mendeleev created the first periodic table of the elements in 1869. Periodic describes something that occurs or repeats at regular intervals.

• Mendeleev arranged the elements in order of increasing atomic mass. Elements with similar properties fell into a repeating pattern.

• He used his table to predict that elements with certain properties would be discovered later.



Changing the Arrangement

• Moseley determined the number of protons—the atomic number—in an atom. He then rearranged the periodic table by placing the elements in order of increasing atomic number.

• Horizontally, elements are in order of increasing atomic number. Vertically, elements with similar chemical properties are grouped in columns.


The Periodic TableChapter 7



Periodic Table Overview



The Periodic Table and Classes of Elements

• Elements are classified according to their properties as metals, nonmetals, and metalloids. The zigzag line on the periodic table helps you locate the metals, nonmetals, and metalloids.

• Most elements are metals. Metals are located to the left of the zigzag line. Most metals are shiny, malleable, and conduct electric current.



The Periodic Table and Classes of Elements, continued• Nonmetals are located to the right of the zigzag line.

Many properties of nonmetals are the opposite of the properties of metals.

• Metalloids, also called semimetals, border the zigzag line. Metalloids have some properties of metals and some of nonmetals.



Comparing Metals, Nonmetals, and Metalloids



Decoding the Periodic Table

• Each square on the periodic table includes an element’s name, chemical symbol, atomic number, and atomic mass.

• Each horizontal row of elements (from left to right) is called a period.

• As you move across a period, the physical and chemical properties follow a pattern.



Decoding the Periodic Table, continued

• Each vertical column of elements (from top to bottom) is called a group, or family.

• Elements in the same group often have similar chemical and physical properties.

• All of the elements follow the periodic law.



Decoding the Periodic Table, continued

• The periodic law states that the repeating chemical and physical properties of elements change periodically with the atomic numbers of the elements.

• All atoms of the same element have the same number of protons in the nucleus. Atoms that have the same number of protons but different numbers of neutrons are called isotopes.


Section 2 Grouping the ElementsChapter 7

Bellringer

In your Science Journal, write what you have heard or read about the terms alkali and alkaline. For each instance, describe the context in which these terms were used.



What You Will Learn

• Elements in a group often have similar properties because their atoms have the same number of electrons in their outer energy level.

• Hydrogen is set off by itself in the periodic table because its properties do not match the properties of any one group.

• Metals are in Groups 1-16. Metalloids are in Groups 13-16. Nonmetals are in Groups 14-18. Noble gases are in Group 18.



Group 1: Alkali Metals

• The elements in a group have similar properties because the atoms of the elements have similar numbers of electrons in their outer energy level.

• In order to have a complete set of electrons in their outer level, atoms will often take, give, or share electrons with other atoms. Elements whose atoms undergo such processes are called reactive.



Group 1: Alkali Metals, continued

• Alkali metals are elements in Group 1 of the periodic table.

• Alkali metals are the most reactive metals. Their atoms easily give away the one electron in the outer level of their atoms.

• Alkali metals are so reactive that in nature they are found only combined with other elements.



Group 2: Alkaline-Earth Metals

• Alkaline-earth metals are elements in Group 2. They are less reactive than alkali metals are.

• Atoms of alkaline-earth metals have two electrons in their outer level.

• Group 2 elements and their compounds have many uses.



Groups 3-12: Transition Metals

• Elements of Groups 3-12 are called transition metals.

• Transition metals are less reactive than alkali metals and alkaline-earth metals.

• The lanthanides and actinides make up two rows of transition metals that are placed at the bottom of the table to save space.



Groups 3-12: Transition Metals, continued

• Transition metals have 1 or 2 electrons in the outer level of their atoms. So, the properties of the transition metals vary.

• But because these elements are metals, they share the properties of metals.



Group 13: Boron Group

• The elements in Group 13 have 3 electrons in the outer level of their atoms.

• Elements in Group 13 are reactive.

• Group 13 contains one metalloid and five metals. Aluminum is the most common element in Group 13.



Group 14: Carbon Group

• The elements in Group 14 have 4 electrons in the outer level of their atoms. Their reactivity varies.

• Group 14 contains metals, nonmetals, and metalloids.

• Diamond and soot are both natural forms of the nonmetal carbon.



Group 15: Nitrogen Group

• The elements in Group 15 have 5 electrons in the outer level of their atoms. Their reactivity varies.




Group 16: Oxygen Group

• The elements in Group 16 have 6 electrons in the outer level of their atoms. These elements are reactive.




Group 17: Halogens

• The elements in Group 17 are called halogens. They have 7 electrons in the outer level of their atoms.

• Halogens are very reactive because their atoms need to gain only one electron to have a complete outer level.

• All halogens are nonmetals.



Group 18: Noble Gases

• The elements in Group 18 are called noble gases. Atoms of noble gases have a full set of electrons in their outer level.

• Noble gases are unreactive. These elements were first called inert gases.

• All noble gases are nonmetals.



Hydrogen

• The properties of hydrogen do not match the properties of any single group, so hydrogen is set apart in the table.

• Hydrogen has one electron in the outer level of its atoms. Hydrogen is reactive.

• Hydrogen is the most abundant element in the universe.


Chapter 7 The Periodic Table

Use the terms below to complete the concept map on the next slide.

elementsperiodsmetalselectrons

nonmetalsperiodic tablefamilies

Concept Map



Concept Map

Chapter 7 Preview Section 1 Arranging the Elements

Documents

Transcript of Chapter 7 Preview Section 1 Arranging the Elements