1. 1.5 – Atomic Trends

2. The periodic table in its early early early early days

7. Period: horizontal row on the periodic table (left  right)

8. Family or Group: vertical column on the periodic table (up & down)
elements in a column share similar properties

9. The Families on the Periodic Table

10. Hydrogen

11. Alkali Metals

12. Alkaline Earth Metals

13. Transition Metals

14. Halogens

15. Noble Gases

17. Want your bad romance

18. 1.5 – Atomic Trends: Atomic Radii
Crude approximation – remember the location of electrons are described as a probability. You can’t physically measure this distance.
Want to know this so we can predict behaviours, such as reactivity.

19. + + + + + decreases e- e- e- e- e- the #p increases
Across a period, the atomic radius _________________ the number of protons increases
force of attraction from protons increases  electrons move closer
the #p increases
force of attraction from protons increases
electrons move closer  smaller radii
I have cookies + + + + e- e- e- e- e- +

20. increases Down a group, the atomic radius __________________
the number of electrons also increases
increasing electron-electron repulsion
inner electrons shields outer electrons from the pull of the nucleus
electrons occupy orbitals that are increasingly further away from the nucleus (gain in shells)

21. more shells = bigger size #e- also increases,
Down a group, the atomic radius ________________
# of shells increases
more shells = bigger size
#e- also increases,
creates electron-electron repulsion
creates electron shielding

22. Electron-electron repulsion
Excuse me, but you’re like, totally in my bubble
Oh dude, personal space + + + + e- e- e- e- e- +

23. Electron Shielding + + + + e- e- e- e- e- +

24. Electron Shielding + + + + e- e- e- e- e- +

26. Which is bigger? Ca Co

27. Which is bigger? Mg Al

28. Which is bigger? Ba Ca

29. Which is bigger? Li Ba

30. Add electrons to create an anion? ________________
# of e- > # of p
ratio of p:e- goes down
every e- effectively feels less attractive power from nucleus
increases

32. Remove electrons to create a cation? ________________
# of p > # of e-
ratio of p:e- goes up
every e- effectively feels more attractive power from nucleus
decreases

34. Consider this: Which has a larger effect on atomic radii, a change in the number of protons, or a change in the number of electrons? Change in #e-

35. Example: Consider the following pairs of atoms
Example: Consider the following pairs of atoms. Which atom has the larger atomic radius?
O or O2-?
2 e- are added in O2-
effect of positive charge from the nucleus distributed among 2 additional e- in O2-
increased electron-electron repulsion in O2-
O2- is larger

36. Example: Consider the following pairs of atoms
Example: Consider the following pairs of atoms. Which atom has the larger atomic radius?
 Ca and Ca2+
2 e- are lost in Ca2+
nucleus has 2 less electrons to pull in Ca2+  remaining electrons feel stronger pull
decreased electron-electron repulsion in Ca2+
Ca is larger

37. Which is the biggest? Na Mo Ra

38. Which is the biggest? Na
Na+

39. Which is the biggest? Cr
Cr3+

40. Which is the smallest? Cr
Cr3+
Cr2+

41. Which is the smallest? F F-

42. Arrange the following in order of increasing atomic radii.
Na, Mg, K, F
F < Mg < Na < K

43. Arrange the following in order of increasing atomic radii.
Br < Cu < K < Rb
K, Cu, Br, Rb

44. Arrange the following in order of increasing atomic radii.
Ca2+ < P < Na < P3-
Na, Ca2+, P, P3-

45. 1.6 – Atomic Trends: Electronegativity
Electronegativity: an atom’s ability to attract electrons towards itself
moving across a period: increases
#p increases
Atomic radii decreases: distance from nucleus to valence e- of another atom decreases
moving down a group: decreases
atomic radii increases: distance from nucleus to valence e- of another atom increases

46. What Can You Say About Reactivity?

48. Apply Knowledge: Use what you have learned to explain the reactivity trend of the alkali metals. The reaction occurs when the metal atom donates its valence electrons to water.
The atomic radii increases going down a family, and electronegativity decreases. This means that valence electrons are held less and less tightly as we go down a group, making it easier for metals to lose them in a reaction. The easier and quicker metals lose their valence electrons, the stronger and faster the reaction.

49. Example: Circle the most reactive element in each list.
Li Na K
Zn Cs K
N F Br

50. Example: Circle the most reactive element in each list.
Li Na K
Zn Cs K
N F Br

51. Example: Circle the most reactive element in each list.
Li Na K
Zn Cs K
N F Br

52. Example: Circle the element that is more metallic in each list.
Cr K Ti
Nb Ta V
Ca Mg Be

53. Example: Circle the element that is more metallic in each list.
Cr K Ti
Nb Ta V
Ca Mg Be

54. Example: Circle the element that is more metallic in each list.
Cr K Ti
Nb Ta V
Ca Mg Be