1. Periodic Trends The Periodic Law Classification of Elements
Electron Configurations in Groups
Trends in Atomic Size
Trends in Energy

2. Mendeleev’s Periodic Table
Dmitri Mendeleev arranged the elements in his periodic table in order of increasing atomic mass.
The periodic table can be used to predict the properties of undiscovered elements.
Henry Moseley updated Mendeleev’s design by ordering elements by atomic number, rather than atomic mass.

3. The Periodic Law
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?

4. The Periodic Law
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.

5. Metals, Nonmetals, and Metalloids
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?

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

7. Metals, Nonmetals, and Metalloids
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.

8. Metals, Nonmetals, and 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.

9. 1. The modern periodic table has elements arranged in order of
QUESTIONS
1. The modern periodic table has elements arranged in order of
colors.
melting and boiling points.
increasing atomic mass.
increasing atomic number.

10. 2. Mendeleev arranged the elements in his periodic table in order of increasing
atomic number.
number of protons.
number of electrons.
atomic mass

11. 3. Which one of the following is NOT a general property of metals?
ductility
malleability
having a high luster
poor conductor of heat and electricity

12. Squares in the Periodic Table
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?

13. Squares in the Periodic Table
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.

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

15. Electron Configurations in Groups
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.

16. Electron Configurations in Groups
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.
The group number equals the number of electrons in the highest occupied energy level.

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

18. Electron Configurations in Groups
In atoms of the Group 4A elements below, there are four electrons in the highest occupied energy level.

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

20. Transition Elements
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, (also called rare- earth metals) the highest occupied s sublevel and a nearby f sublevel generally contain electrons.

21. Transition Elements Blocks of 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?

22. QUESTIONS
4. Which of the following information about elements is usually NOT included in a periodic table?
color
symbol
atomic number
atomic mass

23. 5. An alkali metal would have in the highest occupied energy level
an s2 electron.
an s1 electron.
p2 electrons.
p6 electrons.

24. 6. Which one of the following is incorrectly labeled?
Ne, noble gas
Cu, transition metal
Ga, transition metal
Cl, halogen

25. Trends in Atomic Size 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.

26. Trends in Atomic Size
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?

27. Ions .
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?

28. Ions .
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?

29. Ions Some compounds are composed of particles called ions.
An ion is an atom or group of atoms that has a positive or negative charge.
A cation is an ion with a positive charge.
An anion is an ion with a negative charge.

30. Trends in Ionization Energy
The energy required to remove an electron from an atom is called ionization energy.
The energy required to remove the first electron from an atom is called the first ionization energy.
The energy required to remove an electron from an ion with a 1+ charge is called the second ionization energy.

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

32. Trends in Ionization Energy
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?

33. Trends in Ionic Size Trends in Ionic Size
During reactions between metals and nonmetals, metal atoms tend to lose electrons, and nonmetal atoms tend to gain electrons. The transfer has a predictable effect on the size of the ions that form.

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

35. Trends in Ionic Size Relative Sizes of Some Atoms and Ions
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?

36. Trends in Ionic Size 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.

37. Trends in Electronegativity
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.

38. Trends in Electronegativity
Representative Elements in Groups 1A through 7A

39. Summary of Trends Nuclear Charge Electronegativity Size of anions
Ionic size
Ionization energy
Shielding
Atomic Size
Size of cations
Decreases
Constant
Increases
Decreases
Increases
Properties that vary within groups and across periods include atomic size, ionic size, ionization energy, electronegativity, nuclear charge, and shielding effect. Interpreting Diagrams Which properties tend to decrease across a period?

40. 7. Which of the following sequences is correct for atomic size?
Questions
7. Which of the following sequences is correct for atomic size?
Mg > Al > S
Li > Na > K
F > N > B
F > Cl > Br

41. 8. Metals tend to gain electrons to form cations.
gain electrons to form anions.
lose electrons to form anions.
lose electrons to form cations.

42. 9. Which of the following is the most electronegative?Cl Se Na I