1. Trends & the Periodic Table

2. Trends
Periodic Trends – patterns that can be seen with our current arrangement of the elements (Moseley)
Trends we’ll be looking at:
Atomic Radius
Ionization Energy
3. Electronegativity

3. Atomic Radius
Atomic radius: the radius of the atom. This is an indication of the atom’s volume.
Affected by
1. # of energy
levels
2. Proton Pulling
Power

4. Increasing Atomic Radius

5. Group Trend
                                                                                                                                                                                                                  
Atoms at the bottom of the PT have more energy levels and subatomic particles which make the atomic radius bigger.

6. Period Trend
As you go from left to right, you gain more protons (the atomic number increases)
The more protons you have, the more Proton Pulling Power
Because the nucleus are + and the electrons are – ,the electrons get pulled towards the nucleus.

7. More protons = greater PPP “proton pulling power”
Period Trend
More protons = greater PPP “proton pulling power”

8. Atomic Radius

9. Ionization Energy
= amount energy required to remove a valence electron. Closely related to electronegativity.

10. Increasing Ionization Energy

11. Group Trend
Elements at the bottom of PT have valence e- that are much further away from nucleus
Inner electrons shield the charge felt by the valance e- (Shielding Affect)
attraction much weaker so it’s easier to steal e- away

12. Period Trend
Elements at the right of the PT are so close to achieving the “octet rule”
This requires a lot of energy to take one of their e-

13. Electronegativity An atom’s “desire” to grab another atom’s electrons.
noble gases tend not to form bonds, so don’t have electronegativity values

14. Increasing Electronegativity

15. Group Trend
Elements near the top of the periodic table have few electrons; every electron is a big deal.
They have a stronger desire to acquire more electrons.
Elements near the bottom of the chart have so many electrons that loosing or gaining an electron is not as big a deal.

16. Period Trend
Elements at the right of the PT are so close to achieving the “octet rule”
They have a strong “desire” to achieve the octet.
Elements on the left would rather give electrons away to drop down an energy level.

17. How do you know if an atom gains or loses electrons?
Atoms form ions to get a valence of 8
(or 2 for H)
Metals tend to have 1, 2, or 3 valence electrons
It’s easier to lose them (CATIONS)
Nonmetals tend to have 5, 6, or 7 valence electrons
It’s easier to add some (ANIONS)
Noble gases already have 8 so they don’t form ions very easily

18. Most reactive metal = Fr (the most metallic)
Increased Electronegativity
Increased Ionization Energy
Increasing Atomic Radius
Most Reactive Nonmetal
= F
Increased Electronegativity
Increased Ionization Energy (easier to remove an electron)
Increasing Atomic Radius
Most reactive metal = Fr
(the most metallic)