1. Periodic Trends 6.3
Section 6.3-2
Periodic Trends II

2. Some compounds are composed of particles called ions.
6.3-2
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.

3. Trends in Ionization Energy
6.3-2
Trends in Ionization Energy
Trends in Ionization Energy
What are the trends among the elements for first ionization energy, ionic size, and electronegativity?

4. Trends in Ionization Energy
6.3-2
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.

5. Trends in Ionization Energy
6.3-2
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.

6. Trends in Ionization Energy
6.3-2
Trends in Ionization Energy

7. Trends in Ionization Energy
6.3-2
Trends in Ionization Energy
Largest
Smallest

8. Trends in Ionization Energy
6.3-2
Trends in Ionization Energy
largest
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?
smallest

9. Trends in Electronegativity
6.3-2
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 decrease from top to bottom within a group. For representative elements, the values tend to increase from left to right across a period.

10. Trends in Electronegativity
6.3-2
Trends in Electronegativity
Representative Elements in Groups 1A through 7A
Largest
Smallest

11. Summary of Trends What is the underlying cause of periodic trends?
6.3-2
Summary of Trends
Summary of Trends
What is the underlying cause of periodic trends?

12. 6.3-2
Summary of Trends
The trends that exist among these properties can be explained by variations in atomic structure.

13. Nuclear Charge Electronegativity Size of anions Ionic size
6.3-2
Summary of Trends
Nuclear Charge
Electronegativity
Size of anions
Ionic size
Ionization energy
Shielding
Size of cations
Atomic Size
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?

14. 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

15. 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.

16. 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

17. The End ! !