6.1 The Periodic Law How is the modern periodic table organized?

6.1 In the modern periodic table, elements are arranged in order of increasing atomic number. In the modern periodic table, the elements are arranged in order of increasing atomic number. Interpreting Diagrams How many elements are there in the second period?

6.1 The periodic law: When elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties. The properties of the elements within a period change as you move across a period from left to right. The pattern of properties within a period repeats as you move from one period to the next.

Metals, Nonmetals, and Metalloids 6.1 Metals, Metalloids, and Nonmetals One way to classify elements in the periodic table is as metals, nonmetals, and metalloids. Inferring What is the purpose for the black stair-step line?

Metals, Nonmetals, and Metalloids 6.1 Metals, Metalloids, and Nonmetals in the Periodic Table One way to classify elements in the periodic table is as metals, nonmetals, and metalloids. Inferring What is the purpose for the black stair-step line?

Metals, Nonmetals, and Metalloids 6.1 Metals, Metalloids, and Nonmetals in the Periodic Table One way to classify elements in the periodic table is as metals, nonmetals, and metalloids. Inferring What is the purpose for the black stair-step line?

Metals, Nonmetals, and Metalloids 6.1 Metals, Metalloids, and Nonmetals in the Periodic Table One way to classify elements in the periodic table is as metals, nonmetals, and metalloids. Inferring What is the purpose for the black stair-step line?

Metals, Nonmetals, and Metalloids 6.1 Metals Metals are good conductors of heat and electric current. 80% of elements are metals. Metals have a high luster, are ductile, and are malleable.

Metals, Nonmetals, and Metalloids 6.1 Nonmetals In general, nonmetals are poor conductors of heat and electric current. Most nonmetals are gases at room temperature. A few nonmetals are solids, such as sulfur and phosphorus. One nonmetal, bromine, is a dark-red liquid.

Metals, Nonmetals, and Metalloids 6.1 Metalloids A metalloid generally has properties that are similar to those of metals and nonmetals. The behavior of a metalloid can be controlled by changing conditions.

Squares in the Periodic Table 6.2 The periodic table displays the symbols and names of the elements, along with information about the structure of their atoms. This is the element square for sodium from the periodic table. Interpreting Diagrams What does the data in the square tell you about the structure of sodium atoms?

Squares in the Periodic Table 6.2 The background colors in the squares are used to distinguish groups of elements. The Group 1A elements are called alkali metals. The Group 2A elements are called alkaline earth metals. The nonmetals of Group 7A are called halogens.

Squares in the Periodic Table 6.2 In this periodic table, the colors of the boxes are used to classify representative elements and transition elements.

6.2 Elements can be sorted into noble gases, representative elements, transition metals, or inner transition metals based on their electron configurations.

Electron Configurations in Groups 6.2 The Noble Gases The noble gases are the elements in Group 8A of the periodic table. The electron configurations for the first four noble gases in Group 8A are listed below.

6.2 The Representative Elements Elements in groups 1A through 7A are often referred to as representative elements because they display a wide range of physical and chemical properties. The s and p sublevels of the highest occupied energy level are not filled.

Electron Configurations in Groups 6.2 In atoms of the Group 1A elements below, there is only one electron in the highest occupied energy level.

Electron Configurations in Groups 6.2 In atoms of the Group 4A (or 14) elements below, there are four electrons in the highest occupied energy level.

6.2 Transition Elements There are two types of transition elements— --transition metals and --inner transition metals. They are classified based on their electron configurations.

6.2 In atoms of a transition metal, the highest occupied s sublevel and a nearby d sublevel contain electrons. In atoms of an inner transition metal, the highest occupied s sublevel and a nearby f sublevel generally contain electrons.

6.2 Blocks of Elements Transition Elements This diagram classifies elements into blocks according to sublevels that are filled or filling with electrons. Interpreting Diagrams In the highest occupied energy level of a halogen atom, how many electrons are in the p sublevel?

Periodic Trends in Atomic Properties Ionization Energy Electron Affinity Atomic size Copyright©2000 by Houghton Mifflin Company. All rights reserved.

6.3 Trends in Atomic Size The atomic radius is one half of the distance between the nuclei of two atoms of the same element when the atoms are joined. This diagram lists the atomic radii of seven nonmetals. An atomic radius is half the distance between the nuclei of two atoms of the same element when the atoms are joined.

Trends in Atomic Size 6.3 Group and Periodic Trends in Atomic Size In general, atomic size increases from top to bottom within a group and decreases from left to right across a period.

Figure 7.35 Atomic Radii for Selected Atoms Copyright©2000 by Houghton Mifflin Company. All rights reserved.

Trends in Atomic Size 6.3 The size of atoms tends to decrease from left to right across a period and increase from top to bottom within a group. Predicting If a halogen and an alkali metal are in the same period, which one will have the larger radius?

Ions 6.3 Ions How do ions form?

Ions 6.3 Positive and negative ions form when electrons are transferred between atoms. When a sodium atom loses an electron, it becomes a positively charged ion. When a chlorine atom gains an electron, it becomes a negatively charged ion. Interpreting Diagrams What happens to the protons and neutrons during these changes?

Ions 6.3 Positive and negative ions form when electrons are transferred between atoms. When a sodium atom loses an electron, it becomes a positively charged ion. When a chlorine atom gains an electron, it becomes a negatively charged ion. Interpreting Diagrams What happens to the protons and neutrons during these changes?

Trends in Ionization Energy 6.3 Trends in Ionization Energy

Trends in Ionization Energy 6.3 The energy required to remove the first electron from an atom is called the first ionization energy.

Trends in Ionization Energy 6.3 First ionization energy tends to decrease from top to bottom within a group and increase from left to right across a period.

Trends in Ionization Energy 6.3

Trends in Ionization Energy 6.3

Trends in Ionization Energy 6.3 First ionization energy tends to increase from left to right across a period and decrease from top to bottom within a group. Predicting Which element would have the larger first ionization energy—an alkali metal in period 2 or an alkali metal in period 4?

6.3 Cations are always smaller than the atoms from which they form. Trends in Ionic Size 6.3 Cations are always smaller than the atoms from which they form. Anions are always larger than the atoms from which they form.

6.3 Relative Sizes of Some Atoms and Ions Trends in Ionic Size This diagram compares the relative sizes of atoms and ions for selected alkali metals and halogens. The data are given in picometers. Comparing and Contrasting What happens to the radius when an atom forms a cation? When an atom forms an anion?

6.3 Trends in Ionic Size Size generally increases The ionic radii for cations and anions decrease from left to right across periods and increase from top to bottom within groups.

6.3 Electronegativity is the ability of an atom of an element to attract electrons when the atom is in a compound. In general, electronegativity values decrease from top to bottom within a group. For representative elements, the values tend to increase from left to right across a period.

Trends in Electronegativity 6.3 Trends in Electronegativity Representative Elements in Groups 1A through 7A

Copyright©2000 by Houghton Mifflin Company. All rights reserved. Electron Affinity The energy change associated with the addition of an electron to a gaseous atom. X(g) + e  X(g) If addition of an electron is exothermic, then EA is negative. Copyright©2000 by Houghton Mifflin Company. All rights reserved.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. EA generally becomes more negative from L  R across a period. EA becomes more positive as you go down a group. There are numerous EXCEPTIONS! Copyright©2000 by Houghton Mifflin Company. All rights reserved.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. Figure 7.33 The Electronic Affinity Values for Atoms Among the First 20 Elements that Form Stable, Isolated X- Ions Copyright©2000 by Houghton Mifflin Company. All rights reserved.

Information Contained in the Periodic Table Grps. of Representative elements exhibit similar chemical properties that change in a regular way. Each group has the same valence electron configuration. Copyright©2000 by Houghton Mifflin Company. All rights reserved.

Copyright©2000 by Houghton Mifflin Company. All rights reserved. It is the number and type of valence electrons that primarily determine an atoms chemistry. Copyright©2000 by Houghton Mifflin Company. All rights reserved.

Figure 7.36 Special Names for Groups in the Periodic Table Copyright©2000 by Houghton Mifflin Company. All rights reserved.