1. Create an orbital diagram for: Nitrogen Neon
Section 3 Electron Configuration and Periodic Properties
Chapter 5
Bellwork November 29, 2011
Create an orbital diagram for:
Nitrogen
Neon
Write the electron configuration for:
Chlorine
Chromium
Strontium
Barium

2. Section 3 Electron Configuration and Periodic Properties
Chapter 5
Objectives
Define atomic radius, ionization energy, and electronegativity.
Compare periodic trends of 1) atomic radii ) ionization energy 3) electronegativity, and state the reasons for these variations.

3. Section 3 Electron Configuration and Periodic Properties
Chapter 5
Atomic Radii

4. Atomic Radii: THE DEFINITION
Section 3 Electron Configuration and Periodic Properties
Chapter 5
Atomic Radii: THE DEFINITION
The Atomic radius is the distance from the nucleus to the outermost electron.
Don’t need to copy this, Official Definition:
The official definition is half distance between the nuclei of any two atoms when the element is isolated and in its standard state. (e.g. Cl2, Na metal)

5. Section 3 Electron Configuration and Periodic Properties
Chapter 5
Atomic Radii
Of the elements carbon, nitrogen, oxygen, and fluorine which would you expect to have the largest atomic radius?

6. Atomic Radii, left to right
Section 3 Electron Configuration and Periodic Properties
Chapter 5
Atomic Radii, left to right
THE TREND: Atoms tend to be smaller the farther to the right they are found across a period.
Why??
Write the electron configuration for C, N, O, and F
Do the electrons enter higher energy levels?
What happens to the number of protons as you move from Carbon to Fluorine?
What are electrons attracted to?

7. Effective nuclear charge
Section 3 Electron Configuration and Periodic Properties
Chapter 5
Effective nuclear charge
Effective nuclear charge: The net positive charge experienced by an electron in an atom.
As you move left to right across the periodic table the effective nuclear charge increases and therefore the electrons are pulled closer to the nucleus.

8. Atomic Radii, continued
Section 3 Electron Configuration and Periodic Properties
Chapter 5
Atomic Radii, continued
Sample Problem A
Of the elements magnesium (Mg), chlorine (Cl), sodium (Na), and phosphorus (P), which has the largest atomic radius? Which as the shortest?
Create an electron configuration for every element before you answer the question above!!!

9. Atomic Radii, top to bottom
Section 3 Electron Configuration and Periodic Properties
Chapter 5
Atomic Radii, top to bottom
THE TREND: Atoms tend to be larger the farther down in a group they are found.
THE EXPLANATION: The trend to larger atoms down a group is caused by the increasing size of the electron cloud around an atom as the number electron sublevels and energy levels increases.

10. Atomic Radii, continued
Section 3 Electron Configuration and Periodic Properties
Chapter 5
Atomic Radii, continued
Sample Problem B
Of the elements magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba), which has the largest atomic radius? Which as the shortest? Explain your answer in terms of trends of the periodic table.
Create an electron configuration for every element before you answer the question above!!!

11. Bellwork Which element has a larger atomic radius? Fluorine Sulfur
Section 3 Electron Configuration and Periodic Properties
Chapter 5
Bellwork
Which element has a larger atomic radius?
Fluorine
Sulfur
Explain your choice. There are two good reasons

12. Ionization Energy Chapter 5
Section 3 Electron Configuration and Periodic Properties
Chapter 5
Ionization Energy

13. Chapter 5 Ionization Energy
Section 3 Electron Configuration and Periodic Properties
Chapter 5
Ionization Energy
An ion is an atom that has a positive or negative charge.
Sodium (Na), for example, easily loses an electron to form Na+.
Chlorine (Cl) easily gains an electron to form Cl –
IMPORTANT: The loss of an electron results in a positive charge and gaining electrons results in a negative charge.

14. Ionization Energy: THE DEFINITION
Section 3 Electron Configuration and Periodic Properties
Chapter 5
Ionization Energy: THE DEFINITION
Any process that results in the formation of an ion is referred to as ionization.
The energy required to remove one electron from a neutral atom of an element is the ionization energy, IE.

15. Ionization Energy, left to right
Section 3 Electron Configuration and Periodic Properties
Chapter 5
Ionization Energy, left to right
THE TREND: In general, ionization energies of the main-group elements increase across each period.
This increase is caused by increasing effective nuclear charge (ENC).
A higher ENC more strongly attracts electrons in the same energy level making them harder to remove.

16. Section 3 Electron Configuration and Periodic Properties
Chapter 5
Ionization Energy, problem A
Which of the elements below would you expect to have the greatest ionization energy?
Lithium
Carbon
Oxygen
Neon

17. Section 3 Electron Configuration and Periodic Properties
Chapter 5
Ionization Energy, top to bottom
THE TREND: Among the main-group elements, ionization energies generally decrease down the groups.
THE EXPLANATION: As you move down a group valence electrons enter higher energy levels.
Electrons in higher energy levels are easier to remove.

19. Section 3 Electron Configuration and Periodic Properties
Chapter 5
Ionization Energy, problem B
Which of the elements below would you expect to have the greatest ionization energy?
Fluorine
Chlorine
Bromine
Iodine

20. The trend

21. Ionization Energy, continued
Section 3 Electron Configuration and Periodic Properties
Chapter 5
Ionization Energy, continued

22. Electron configuration practice
Section 3 Electron Configuration and Periodic Properties
Chapter 5
Electron configuration practice

23. Create an electron configuration for each of the following:
Section 3 Electron Configuration and Periodic Properties
Chapter 5
Connection to electron configurations
Create an electron configuration for each of the following: Ar
Cl- K+
Ca2+
S2-
Remember that a “-” means electrons have been gained and a “+” means electrons have been lost.

24. Electronegativity Chapter 5
Section 3 Electron Configuration and Periodic Properties
Chapter 5
Electronegativity

25. Electronegativity: THE DEFINITION
Section 3 Electron Configuration and Periodic Properties
Chapter 5
Electronegativity: THE DEFINITION
Student friendly explanation
Electronegativity is a measure of which atom is “more attractive” to electrons IN A BOND.
Noble gases don’t have electronegativities because they don’t generally bond.

26. Chapter 5 Sometimes it’s equal
Section 3 Electron Configuration and Periodic Properties
Chapter 5
Sometimes it’s equal

27. Chapter 5 Sometimes it’s not
Section 3 Electron Configuration and Periodic Properties
Chapter 5
Sometimes it’s not

28. Electronegativity, continued
Section 3 Electron Configuration and Periodic Properties
Chapter 5
Electronegativity, continued
Think
What is the charge of an electron?
What are electrons attracted to?
Therefore electrons are attracted to elements ______
____________________________________________

29. Who’s she (the electron) going to choose
Section 3 Electron Configuration and Periodic Properties
Chapter 5
Who’s she (the electron) going to choose e-

30. Section 3 Electron Configuration and Periodic Properties
Chapter 5
Electronegativity, problem A
Which of the elements below would you expect to have the greatest electronegativity? Which has the lowest?
Lithium
Carbon
Oxygen

31. Section 3 Electron Configuration and Periodic Properties
Chapter 5
Electronegativity, problem B
Which of the elements below would you expect to have the greatest electronegativity? Which has the lowest?
Fluorine
Chlorine
Bromine
Iodine