1. Periodic Trends

2. Metals, Nonmetals, Metalloids

3. Metals, Nonmetals, Metalloids
There is a zig-zag or staircase line that divides the table.
Metals are on the left of the line, in blue.
Nonmetals are on the right of the line, in orange.

4. Metals, Nonmetals, Metalloids
Elements that border the stair case, shown in purple are the metalloids or semi-metals.
Aluminum & Polonium are more metallic than not.

5. 10/10 The Periodic Law “add to your TOC”
When arranged by increasing atomic number, the chemical elements display a regular and repeating pattern of chemical and physical properties.

6. The Periodic Law
Atoms with similar properties appear in groups or families (vertical columns) on the periodic table.
They are similar because they all have the same number of valence (outer shell) electrons, which governs their chemical behavior.

7. Periodic Trends
There are several important atomic characteristics that show predictable trends that you should know.
The first and most important is atomic radius.
Radius is the distance from the center of the nucleus to the “edge” of the electron cloud.

8. Atomic Radius
The trend for atomic radius in a vertical column is to go from smaller at the top to larger at the bottom of the family.
Why?
With each step down the family, we add an entirely new energy level

9. Atomic Radius The trend across a horizontal period is less obvious.
What happens to atomic structure as we step from left to right?
Each step adds a proton and an electron (and 1 or 2 neutrons).
Electrons are added to existing energy levels
The nucleus is more positive and the electron cloud is more negative.

10. Atomic Radius
The increased attraction pulls the cloud in, this is called Effective nuclear charge.
The closer an electron is to the nucleus, the more pull it feels from the nucleus.
As effective nuclear charge increases, the electron cloud is pulled in tighter.
As you move across the periods the atomic radius actually decreases.

11. The Periodic Table and Atomic Radius

12. Atomic Radius
On your help sheet, draw black arrows like this:

13. Example: Which is larger: a lithium atom or a fluorine atom?

14. Example: Which is larger: an arsenic atom or a sulfur atom?

15. Ionization Energy
The energy required to remove a valence electron from an atom is ionization energy.
The smaller the atom is, the harder its electrons are to remove.
Ionization energy and atomic radius are inversely proportional or opposites

16. Ionization Energy (Potential)
Draw red arrows on your help sheet like this:

17. Example: Which has a higher ionization energy: a
lithium atom or a fluorine atom?
A fluorine atom

18. Example:
Which has a higher ionization energy: an arsenic atom or a sulfur atom?
A sulfur atom

19. Electronegativity
Electronegativity is a measure of an atom’s attraction for another atom’s valence electrons.
Generally, metals are electron givers and have low electronegativities.
Nonmetals are are electron takers and have high electronegativities.
What about the noble gases?

20. Electronegativity
Draw green arrows on your help sheet like this:

21. Example: Which has a higher electronegativity: a
beryllium atom or a oxygen atom?
A oxygen atom

22. Example:
Which has a higher electronegativity: a neon atom or a chlorine atom?
A chlorine atom

23. Need out worksheet from Tuesday
We will go over it

24. Quiz on Friday over periodic trends
10/12 PERIODIC TRENDS PRACTICE QUESTIONS:
Define atomic radius:
Arrange the following elements in order of decreasing atomic size:
a) sulfur, chlorine, aluminum, and sodium.
b) carbon, germanium, lead, silicon
c) cesium, lead, bismuth, barium
3. Define electronegativity:
4. In each of the following pairs, which element is the most electronegative?
a) chlorine, fluorine
b) carbon, nitrogen
c) magnesium, neon
d) arsenic, calcium

25. 5. Define ionization energy:  
6. Arrange the following elements in order of increasing ionization energy:
a) Be, Mg, Sr
b) Bi, Cs, Ba
c) Na, Al, S
7. Answer the questions below for the elements:
B Al Ga In
a) Lowest electronegativity?
b) Highest ionization energy?
c) Largest atomic radius?
d) Which are non-metals?
e) List them in order from small to large.
f) Would they gain or lose electrons to achieve octet?

26. Check your work:
Atomic radius is the distance from the center of the nucleus to the “edge” of the electron cloud
a. Na, Al, S, Cl
b. Pb, Ge, Si, C
c. Cs, Ba, Pb, Bi
3. Electronegativity is a measure of an atom’s attraction for another atom’s valence electrons.
4. a. F
b. N
c. Ne
d. As

27. 5. Ionization energy is the energy required to remove a valence electron from an atom is ionization energy.
6. a. Sr, Mg, Be
b. Cs, Ba, Bi
c. Na, Al, S
7. a. In
b. B
c. In
d. B (since to right of line, is a metalloid but can be a non- metal)
e. B, Al, Ga, In
f. lose 3 valence e- to achieve octet in outer orbital since they are all in the 3rd “tall column”

29. Overall Reactivity
This ties all the previous trends together in one package.
However, we must treat metals and nonmetals separately.
The most reactive metals are the largest since they are the best electron givers.
The most reactive nonmetals are the smallest ones, the best electron takers.

30. Overall Reactivity
Your help sheet will look like this:

31. The Octet Rule
The “goal” of most atoms (except H, Li and Be) is to have an octet or group of 8 electrons in their valence energy level.
They may accomplish this by either giving electrons away or taking them.
Atoms that have gained or lost electrons are called ions.

32. Ions
When an atom gains an electron, it becomes negatively charged (more electrons than protons ) and is called an anion.
Metal atoms lose electrons. They become positively charged cations.

33. Positive ions = Cations
Positive ions are always smaller than the neutral atom. Loss of outer shell electrons.

34. Negative Ions = Anions
Negative ions are always larger than the neutral atom. Gaining electrons.