The document discusses several atomic properties including atomic radius, ionic radius, ionization energy, electronegativity, nuclear charge, and shielding effect. It provides trends within the periodic table, noting that atomic radius increases down a group and decreases left to right across a period. Ionic radius also decreases left to right within a period and increases down a group. Ionization energy increases left to right within a period and decreases down a group. Electronegativity increases left to right within a period and decreases down a group. The document also examines nuclear charge and shielding effect.

1. Atomic Radius – distance from
nucleus of an atom to the outermost
electron. Measured in picometers

2. Atomic Radius Trend
• Group Trend – As you go down a
column, atomic radius increases
• Periodic Trend – As you go across a
period (L to R), atomic radius
decreases

4. Atomic radius vs. atomic number (Period)Atomic radius vs. atomic number (Period)
Ca
K
H He
Li
B
Be
C N O F
Ne
Na
Mg
Al Si P S Cl
Ar
0
50
100
150
200
250
0 2 4 6 8 10 12 14 16 18 20
Element
AtomicRadius(pm)

7. Ionic Radius
Ionic radius, rion, is the radius of an
atom's ion.

8. Ionic Radius in a Period
• Ionic Radius tends to decrease in size across
the Periodic Table

10. Ionic Radius in a Group
• Ionic Radius tends to increase down a Group

11. Summary Diagram

12. • Which of the following is the smallest in
size?
• 1) N3-
• 2) O2-
• 3) F-
• 4) Na+
Question 1

13. Question 2
The correct order of radii is:
•a) N < Be < B
•b) F-
< O2-
< N3-
•c) Na < Li < K
•d) Fe3+
< Fe2+
< Fe4+

14. Question 3
The correct order of ionic radii is:
•a) Ti4+
< Mn7+
•b) 37
Cl-
< 35
Cl-
•c) K+
> Cl-
•d) P3+
> P5+

15. Ionization Energy
• The ionization energy (IE) is qualitatively
defined as the amount of energy required to
remove the most loosely bound electron of
an isolated gaseous atom to form a cation.

16. IE in a Period
Ionization generally increases
across a period.

17. IE in a Group
IE generally
goes down in
a Group

18. Summary Diagram

19. Questions

20. Electronegativity
• Electronegativity is a measure of the
tendency of an atom to attract a bonding
pair of electrons.

21. EN in Period tends to increase

22. EN in a Group tends to decrease

23. Summary Diagram

24. Questions
1. Which of the pairs are more
Electronegative:
B or C
Mg or Ca
K or Sc

25. Nuclear Charge
• The effective nuclear charge is the net
positive charge experienced by valence
electrons.

26. Shielding Effect
• Shielding
effect can be
defined as a
reduction in the
effective nuclear
charge on the
electron cloud
• is due to inner
electrons shielding
valence electrons
from the nucleus

27. Nuclear Charge within Group
and Period

28. Questions
• Which elements have a higher nuclear
charge?
– Cr, Ni
– Rb, Sr
– Si, Ge

29. Shielding in a Group or Period

30. Questions
• Which elements experience a larger
shielding affect?
– Ti, V
– Mg, Al
– Cl, Br