1. Periodic Trends Atomic Size Ionization Energy Electron Affinity
There are several important atomic characteristics that show predictable trends that you should know:
Atomic Size
Ionization Energy
Electron Affinity
Electronegativity

2. Atomic Size
The bonding atomic radius is defined as one-half of the distance between bonded nuclei.

3. Decreasing Atomic Size Across a Period
The effect is that the more positive nucleus (+) has a greater pull on the electron cloud (-)
The increased attraction pulls the cloud in, making atoms smaller as we move from left to right across a period Li Be B
1s22s1
1s22s2
1s22s22p1 Li Be B + + + + + + + + + + + +

4. Relative Size of Atoms
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 350

5. atomic radius atomic number 0.3 Cs Rb 0.25 K 0.2 Na La Li 0.15 Zn Xe
transition
series 4d
transition
series
atomic radius La Li
0.15 Zn Xe Kr
0.1 Cl F
0.05 He H
atomic number

6. Atomic Radii INCREASES INCREASES 1 2 13 14 15 16 17 Li Na K Rb Cs Cl S Li Na K Rb Cs Cl S P Si Al Br Se As Ge Ga I Te Sb Sn In Tl Pb Bi Mg Ca Sr Ba Be F O N C B

7. Ionization Energy
Amount of energy required to remove an electron from the ground state of a gaseous atom or ion.
Given enough energy (in the form of a photon) an electron can leave the atom completely.
The number of protons and electrons is no longer equal
IONS!!!

8. Ionization Energy
Generally, as one goes across a row, it gets harder to remove an electron.
The larger the atom is, the easier its electrons are to remove.
Ionization energy and atomic radius are inversely proportional

9. She’s unhappy and negative.
Ions
Here is a simple way to remember which is the cation and which the anion:
This is Ann Ion.
This is a cat-ion.
She’s unhappy and negative.
Cats are “paw-sitive”

10. Sizes of Ions Cations are smaller than their parent atoms.
The outermost electron is removed and repulsions are reduced.

11. Sizes of Ions Anions are larger than their parent atoms.
Electrons are added and repulsions are increased.

12. Ionization Energies INCREASES DECREASES Period Be Al Si Ti V Cr Mn Fe
Group 1 18
DECREASES 1 2 3 4 5 6 7 Be
900 Al
578 Si
787 Ti
659 V
651 Cr
653 Mn
717 Fe
762 Co
760 Ni
737 Cu
746 Zn
906 Ga
579 Ge Nb
652 Mo
684 Tc
702 Ag
731 Cd
868 In
558 Sn
709 Sb
834 Ta
761 W
770 Re Hg
1007 Tl
589 Pb
716 Bi
703 N
1402 O
1314 F
1681 Cl
1251 C
1086 S
1000 Br
1140 I
1008 Na
496 K
419 Rb
403 Cs
376 Ba
503 Fr -- Ra
509 H
1312 B
801 P
1012 As
947 Se
941 Ru
710 Rh
720 Pd
804 Te
869 Os
839 Ir
878 Pt Au
890 Po
812 At
Actinide series Li
520 Ca
590 Sc
633 Sr
550 Y
600 Zr
640 Hf Mg
738 La
538 Ac
490
Lanthanide series   11 12 13 14 15 16 17 9 Ne
2081 Ar
1521 Kr
1351 Xe
1170 Rn
1038 He
2372 Rf Db Sg Bh Hs Mt Ce
534 Pr
527 Nd
533 Pm
536 Sm
545 Eu
547 Gd
592 Tb
566 Dy
573 Ho
581 Er Tm
597 Yb
603 Lu
523 Th
587 Pa
570 U
598 Np Pu
585 Am Cm Bk
601 Cf
608 Es
619 Fm
627 Md
635 No
642 Lr Ds
Uub
Uut
Uuq
Uup
Uuu
Uuo
Symbol
First Ionization Energy
(kJ/mol)‏ 8 10
Period
Linus Pauling ( ) awarded Nobel Prize in chemistry in for his 1939 text, The Nature of the Chemical Bond,
and also won the Nobel Peace Prize in 1962 for his fight to control nuclear weapons.
The greater the electronegativity of an atom in a molecule, the more strongly it attracts the electrons in a covalent bond.

13. Electron Affinity Electron affinity = “Love” of electrons
Energy change accompanying addition of electron to gaseous atom:
Cl + e−  Cl−

14. Electronegativity
Electronegativity is a measure of an atom’s attraction for another atom’s electrons.
Is directly related to Electron Affinity
scale that ranges from 0 to 4.
Fluorine is the most electronegative!!!!

15. Electron Affinity & Electronegativity
INCREASES
DECREASES 1A 8A H
2.1 B
2.0 P As Se
2.4 Ru
2.2 Rh Pd Te Os Ir Pt Au Po At ` 1 1 2A 3A 4A 5A 6A 7A Li
1.0 Be
1.5 Al Si
1.8 Ti V
1.6 Cr Mn Fe Co Ni Cu
1.9 Zn
1.7 Ga Ge Nb Mo Tc Ag Cd In Sn Sb Ta W Re Hg Tl Pb Bi N
3.0 O
3.5 F
4.0 Cl C
2.5 S Br
2.8 I 2 2 Na
0.9 K
0.8 Rb Cs
0.7 Ba Fr Ra
Below 1.0 Mg
1.2 3 3 3B 4B 5B 6B 7B 1B 2B
Period Ca
1.0 Sc
1.3 4 4 Sr
1.0 Y
1.2 Zr
1.4 5 5
Linus Pauling ( ) awarded Nobel Prize in chemistry in 1954 for his text, The Nature of the Chemical Bond,
and also won the Nobel Peace Prize in for his fight to control nuclear weapons.
The greater the electronegativity of an atom in a molecule, the more strongly it attracts the electrons in a covalent bond. La
1.1  Hf
1.3 6 6 Ac
1.1   7
Electronegativity 
Lanthanides:
Actinides:
Hill, Petrucci, General Chemistry An Integrated Approach 2nd Edition, page 373

16. Periodic Trends Atomic Radii - size
Ionization Energy – energy change when losing an e-
Electron Affinity - energy change when gaining an e-
Electronegativity – ability to attract e when in a compound
Forms
cation!
Forms
anion!

17. Summary of Periodic Trends
Atomic radius decreases
Ionization energy increases
Electron affinity increases
Electronegativity increases
Ionization energy decreases
Electron Affinity decreases
Electronegativity decreases
Atomic radius increases 1A 2A 3A 4A 5A 6A 7A
Ionic size (cations) Ionic size (anions)‏
decreases decreases

18. CHEMISTRY /5/13
“Always remember that you are absolutely unique. Just like everyone else.” – Margaret Mead
DO NOW:
In your notes: Which atom has a larger atomic radius:
AGENDA:
Move seats
Students will be able to remember characteristics of the periodic table by completing a coloring activity
HOMEWORK:
Extra credit: Due before winter break: Bring 1 box of tissue or one hand sanitizer (worth 5 pts extra credit)

19. What ion will be formed when K loses 1 e-?
K1+ (cation)
What ion will be formed when O gains 2 e-?
O2- (anion)
Which ion above is more electronegative?