1. Periodic Trends 6.3

2. Warm Up What information can you find on the periodic table? 3.2
Units and Quantities
Warm Up
What information can you find on the periodic table?

3. Squares in the Periodic Table
6.2
Squares in the Periodic Table
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?

4. Squares in the Periodic Table
6.2
Squares in the Periodic Table

5. Electron Configurations in Groups
6.2
Electron Configurations in Groups
The Representative Elements
Elements in groups 1A through 7A: representative elements
The group number equals the number of electrons in the highest occupied energy level.

6. Blocks of Elements 6.2 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?

7. 6.3
Trends in Atomic Size
Trends in Atomic Size
What are the trends among the elements for atomic size?

8. 6.3
Trends in Atomic Size
Trends in Atomic Size
What are the trends among the elements for atomic size?

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

10. 6.3
Trends in Atomic Size
This graph plots atomic radius versus atomic number for 55 elements. INTERPRETING GRAPHS a. Analyzing Data Which alkali metal has an atomic radius of 238 pm? b. Drawing Conclusions Based on the data for alkali metals and noble gases, how does atomic size change within a group? c. Predicting Is an atom of barium, atomic number 56, smaller or larger than an atom of cesium (Cs)?

11. 6.3
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?

12. 6.3
Ions
Ions
How do ions form?

13. 6.3
Ions
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?

14. 6.3
Ions
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?

15. A cation is an ion with a positive charge.
6.3
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.

16. Trends in Ionization Energy
6.3
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.

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

18. Trends in first ionization energy
6.3
Trends in first ionization energy
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?

20. 6.3
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.

21. 6.3
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.

22. Relative Sizes of Some Atoms and Ions
6.3
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?

23. Trends in Electronegativity
6.3
Trends in Electronegativity
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 increase from bottom to top within a group. For representative elements, the values tend to increase from left to right across a period.

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

25. Shielding Effect The more energy levels between the nucleus and valence electrons shield the attractive force between the protons and electrons. This is why the atom expands in size.

26. Reactivity Reactivity for metals increases as you move down and to the left (Fr). For non-metals reactivity increases as you move up and to the right (F).

27. Summary of Trends What is the underlying cause of periodic trends? 6.3

28. 6.3
Summary of Trends
The trends that exist among these properties can be explained by variations in atomic structure.

29. Section Assessment
6.3

30. 1. Which of the following sequences is correct for atomic size?
6.3 Section Quiz
1. Which of the following sequences is correct for atomic size?
Mg > Al > S
Li > Na > K
F > N > B
F > Cl > Br

31. gain electrons to form cations. gain electrons to form anions.
6.3 Section Quiz
2. Metals tend to
gain electrons to form cations.
gain electrons to form anions.
lose electrons to form anions.
lose electrons to form cations.

32. 3. Which of the following is the most electronegative?
6.3 Section Quiz
3. Which of the following is the most electronegative? Cl Se Na I

33. END OF SHOW