1. Periodic Trends
HW 8-10 and 8-11

2. Which atom is biggest? Which is smallest?
Compare: Li, #3, Ne, #10, Na, #11
What particles make up atoms? How many does each element have?
Predict which element you think would be biggest and which would be smallest.
Video link atomic radius

3. 3 10 11 4 10 12 3 10 11 7 Li 3 20 Ne 10 23 Na 11 p: n: e-: p: n: e-:

4. Size of an atom is determined by size of electron cloud

5. Li Ne Na
71 pm
152 pm
186 pm

6. Why is Ne smaller than Li?+3
Li +++

7. Why is Ne smaller than Li?+3
+10
Li +++ Ne

8. Why is Ne smaller than Li?+3
+10
Li +++ Ne
INCREASING THE NUMBER OF PROTONS INCREASES THE ATTRACTION FOR THE VALENCE ELECTRONS OF THE SAME ENERGY LEVEL

9. Atomic Radius

10. Why is Na bigger than Ne?
Na: 1s22s22p6 3s1
Ne: 1s22s22p6

11. Why is Na bigger than Ne? SODIUM HAS AN EXTRA ENERGY LEVEL
Na: 1s22s22p6 3s1
Ne: 1s22s22p6
SODIUM’S VALENCE ELECTRON IS IN LEVEL 3; Ne’s VALENCE ELECTRONS ARE IN LEVEL 2
SODIUM HAS AN EXTRA ENERGY LEVEL

12. K Na Li Li Ar Ne

13. In the periodic table, vertical columns are called groups or families…

14. … while the horizontal rows are called periods.

15. HW 8-11 Li: [He]2s1 Na: [Ne]3s1 K: [Ar]4s1
As we move down a family, an extra energy level is added. The higher the energy level of the valence electrons, the farther the average distance from the nucleus and the larger the atom.

16. Atomic Radius (AR) Make a QUICK sketch of this picture in the box.
Atomic Radius Animation

17. Atomic Radius
Across a period, atomic radius decreases. Reason: More protons pull on electrons which are in orbitals with similar energies.

18. Atomic Radius
Down a group, atomic radius increases. Reason: Elements have electrons in higher energy orbitals, which are farther from the nucleus.

19. Rank the following from largest AR to smallest.
1) Na, K, Rb Answer: Rb > K > Na Reason: Down a family, radius ↑ 2) Na, Si, S Answer: Na > Si > S Reason: Across a period radius ↓

20. Rank the following from largest AR to smallest.
3) N, P, As Answer: As > P > N Reason: Down a family, radius ↑ 4) N, O, F Answer: N > O > F Reason: Across a period radius ↓