1. Bell Ringer (you need Periodic Table packet and test review out on desk)
Turn project in to your period’s lab table. :D

2. Week in Chemistry Day Topic Monday Periodic Trends Tuesday
Go over lab notebooks, Periodic Trends posters
Wednesday
Comprehensive quiz Unit 3
Thursday
Test Review
Friday
Unit 3 Test

3. Assignments Passed Back
Isotope Quiz (quiz)

4. Write the orbital notation for Sodium
Shows increasing energy levels and the orbitals on those levels.
“1s”, “2s”, “2p”, etc – these represent energy levels
1 box – represents one orbital (holds two electrons)
Write the orbital notation for Sodium

5. Periodicity

6. Periodic Trends
Because of the established Periodic Law, scientists began to notice tendencies of certain elemental characteristics to increase or decrease along a row or column of the periodic table of elements. These tendencies are called Periodic Trends.

7. Coulomb’s Law

8. 4 factors that cause the trends
1. Nuclear Pull (Z) – the number of protons
Positive protons pull negative electrons
The protons pull on the outer electrons. The more protons, the more pull exerted by the nucleus on the outer electrons.

9. 4 factors that cause the trends
Electron repulsion – size of e- cloud
Electrons are negative and push away from each other
The more electrons in
an atom’s electron
cloud, the more they
are pushed away from
each other (due to having
the same charge), making
a bigger cloud.

10. 4 factors that cause the trends
3. Shielding electrons – all inner e- shield the valence electrons from nuclear pull
Number of energy levels

11. 4 factors that cause the trends
4. Zeff – the “effective” nuclear pull on outer electrons. The nuclear pull taking into account the shielding electrons which are taking most of the force.
Zeff= # protons - # non-valence electrons
Which element has more effective nuclear pull?
Fluorine
Magnesium OR

12. Periodic Trends – Four Corners
In your corner, determine what the periodic trend is going across the PT and down the PT. Then explain WHY the trend occurs using one or more of the four factors.
Answer the provided questions.
Atomic Radius Ionization Energy
Electronegativity Ionic Size

13. Atomic Radius Trend Draw it!
Increases down a column because the valence electrons are in a farther energy level (higher energy)
Decreases across a period because the nuclear pull is increasing and pulling the energy levels in.
Atomic Size DECREASES
Draw it!
Atomic Size INCREAES

14. CORE Concept
Using the four factors that determine periodic trends, explain the sizes of the atoms.

15. Ionization Energy The energy needed to pull an electron from an atom.
The greater the ionization energy, the more difficult it is to remove an electron.

16. Ionization Energy DECREASES
Decreases down a group because there are more shielding electrons, so it takes LESS ENERGY to “steal” an electron.
Increases across a period because the nuclear pull on those electrons is increased with no extra shielding, so it takes MORE ENERGY to get the electrons away.
Ionization Energy INCREASES
Draw it!
Ionization Energy DECREASES

17. Electronegativity DECREASES
The ability of an atom to take an electron from another atom (wanting to gain an electron)
Decreases down a group because there are more
electrons to shield the nucleus (which does the
pulling)
Increases across a period because of increased Z
(nuclear pull)
Electronegativity
INCREASES
Draw it!
Electronegativity DECREASES

18. Trend
What is it?
Trend across a period
Trend down a group
What causes trend?
Atomic Radius
Size of atom
Decrease
Increase
nuclear pull
increased
More energy levels
Ionization Energy
Energy to remove electron
Nuclear pull increased
Less pull more shielding (bigger)
Electronegativity
Wanting to gain an electron
Closer to full outer ring/ nuclear pull

19. Ionic Size Metals lose electrons (form cations)
less e- repulsion, smaller electron cloud, smaller size
Nonmetals gain electrons (form anions)
more e- repulsion, larger electron cloud, larger size

20. Practice
1) Which is the smallest ion? Explain Na+ Cl- P3- 2) Which has the highest electronegativity? Explain. As Sn S 3) In the following pairs, which has the larger atomic radius? Explain. Mg or Ba Cu or Cu2+ S or S2- 4) In the following pairs, which has the higher ionization energy? Explain. Li or Cs Ca or Br

21. Reminders Assignments Due Date Comprehensive Quiz Test Review
Wednesday, 10/1
Test Review
Friday, 10/3
Unit 3 Test

22. Exit Ticket Which element has a smallest ionic radius?
Which element has a largest ionic radius?
Which element requires the least amount of energy to remove a valence electron?