1. The Periodic Table: Trends
Groups Trends
Period Trends

2. Helium
• Symbol: He
• Atomic Number: 2
• Atomic Mass: 4.0026 amu
• Electron Configuration: 1s2
• Number of Electrons/Shells: 2
• Boiling Point: 4.216 K
• Melting Point: 0.95K
• 1st Ionization: 2372.3 E/kJ mol-1
• Atomic Radius: 31

3. Neon
• Symbol: Ne
• Atomic Number: 10
• Atomic Mass: 20.179 amu
• Electron Configuration: [He] 2s2 2p6
• Number of Electrons/Shells: 2, 8
• Boiling Point: 27.1 K
• Melting Point: 24.7 K
• 1st Ionization: 2080.6 E/kJ mol-1
• Atomic Radius: 38

4. Argon
• Symbol: Ar
• Atomic Number: 18
• Atomic Mass: 39.948 amu
• Electron Configuration: [Ne] 3s2 3p6
• Number of Electrons/Shells: 2,8,8
• Boiling Point: 87.29 K
• Melting Point: 83.6 K
• 1st Ionization: 1520.4 E/kJ mol-1
• Atomic Radius: 71

5. Krypton
• Symbol: Kr
• Atomic Number: 36
• Atomic Mass: 83.80 amu
• Electron Configuration: [Ar] 3d10 4s2 4p6
• Number of Electrons/Shells: 2,8,18,8
• Boiling Point: 120.85 K
• Melting Point: 115.8 K
• 1st Ionization: 1350.7 E/kJ mol-1
• Atomic Radius: 88

6. Xenon
• Symbol: Xe
• Atomic Number: 54
• Atomic Mass: 131.29
• Electron Configuration: [Kr] 4d10 5s2 5p6
• Number of Electrons/Shells: 2,8,18,18,8
• Boiling Point: 166.1 K
• Melting Point: 161.7 K
• 1st Ionization: 1170.4 E/kJ mol-1
• Atomic Radius: 108
• Xenon may form a compound with Fluorine and
Oxygen

7. Radon
• Symbol: Ra
• Atomic Number: 86
• Atomic Mass: (222) amu
• Electron Configuration: [Xe] 4f14 5d10 6s2 6p6
• Number of Electrons/Shells: 2,8,18,32,18,8
• Boiling Point: 211.5 K
• Melting Point: 202.2 K
• 1st Ionization: 1037.1 E/kJ mol-1
• Atomic Radius: 120

8. Francium
• Symbol: Fr
• Atomic Number: 87
• Atomic Mass: (223)
• Electron Configuration: [Rn] 7s1
• Number of Electrons/Shells: 2,8,18,32,18,8,1
• Boiling Point: 300 K
• Melting Point: 950 K
• 1st Ionization: 4.0727
• Atomic Radius: 260

9. Radium
• Symbol: Ra
• Atomic Number: 88
• Atomic Mass: 226.025
• Electron Configuration: [Rn] 7s2
• Number of Electrons/Shells: 2,8,18,32,18,8,2
• Boiling Point: 2010 K
• Melting Point: 973 K
• 1st Ionization: 5.2784
• Atomic Radius: 221

10. Actinium
• Symbol: Ac
• Atomic Number: 89
• Atomic Mass: 227.028
• Electron Configuration: [Rn] 6d1 7s2
• Number of Electrons/Shells: 2,8,18,32,18,9,2
• Boiling Point: 3471 K
• Melting Point: 1323 K
• 1st Ionization: 5.17
• Atomic Radius: 215

11. Thorium
• Symbol: Th
• Atomic Number: 90
• Atomic Mass: 232.038
• Electron Configuration: [Rn] 6d1 7s2
• Number of Electrons/Shells: 2,8,18,32,18,10,2
• Boiling Point: 5061 K
• Melting Point: 2115 K
• 1st Ionization: 6.3067
• Atomic Radius: 206

12. Protactinium
• Symbol: Pa
• Atomic Number: 91
• Atomic Mass: 231.036
• Electron Configuration: [Rn] 5f2 6d1 7s2
• Number of Electrons/Shells: 2,8,18,32,20,9,2
• Boiling Point: Unknown
• Melting Point: 1841 K
• 1st Ionization: 5.89
• Atomic Radius: 200

13. Uranium
• Symbol: U
• Atomic Number: 92
• Atomic Mass: 238.029
• Electron Configuration: [Rn] 5f3 6d1 7s2
• Number of Electrons/Shells: 2,8,18,32,21,9,2
• Boiling Point: 4404 K
• Melting Point: 1405.3 K
• 1st Ionization: 6.1941
• Atomic Radius: 196

14. Neptunium
• Symbol: Np
• Atomic Number: 93
• Atomic Mass: 237.048
• Electron Configuration: [Rn] 5f4 6d1 7s2
• Number of Electrons/Shells: 2,8,18,32,22,9,2
• Boiling Point: Unknown
• Melting Point: Unknown
• 1st Ionization: 6.2657
• Atomic Radius: 190

15. Plutonium
• Symbol: Pu
• Atomic Number: 94
• Atomic Mass: (244)
• Electron Configuration: [Rn] 5f6 7s2
• Number of Electrons/Shells: 28,18,32,24,8,2
• Boiling Point: 3505 K
• Melting Point: 912.5 K
• 1st Ionization: 6.0262
• Atomic Radius: 187

16. Americum
• Symbol: Am
• Atomic Number: 95
• Atomic Mass: (243)
• Electron Configuration: [Rn] 5f7 7s2
• Number of Electrons/Shells: 2,8,18,32,25,8,2
• Boiling Point: 2284 K
• Melting Point: 1449 K
• 1st Ionization: 5.9738
• Atomic Radius: 180

17. Curium
• Symbol: Cm
• Atomic Number: 96
• Atomic Mass: (247)
• Electron Configuration: [Rn] 5f7 6d1 7s2
• Number of Electrons/Shells: 2,8,18,32,25,9,2
• Boiling Point: 3383 K
• Melting Point: 1613 K
• 1st Ionization: 5.9915
• Atomic Radius: 169

18. Berkelium
• Symbol: Bk
• Atomic Number: 97
• Atomic Mass: (247)
• Electron Configuration: [Rn] 5f9 7s2
• Number of Electrons/Shells: 2,8,18,32,27,8,2
• Boiling Point: Unknown
• Melting Point: 1323 K
• 1st Ionization: 6.1979
• Atomic Radius: Unknown

19. Californium
• Symbol: Cf
• Atomic Number: 98
• Atomic Mass: (251)
• Electron Configuration: [Rn] 5f10 7s2
• Number of Electrons/Shells: 2,8,18,32,28,8,2
• Boiling Point: Unknown
• Melting Point: 1173 K
• 1st Ionization: 6.2817
• Atomic Radius: Unknown

20. Einsteinium
• Symbol: Es
• Atomic Number: 99
• Atomic Mass: (252)
• Electron Configuration: [Rn] 5f11 7s2
• Number of Electrons/Shells: 2,8,18,32,29,8,2
• Boiling Point: Unknown
• Melting Point: 1133 K
• 1st Ionization: 6.42
• Atomic Radius: Unknown

21. Fermium
• Symbol: Fm
• Atomic Number: 100
• Atomic Mass: (257)
• Electron Configuration: [Rn] 5f12 7s2
• Number of Electrons/Shells: 2,8,18,32,30,8,2
• Boiling Point: Unknown
• Melting Point: 1800 K
• 1st Ionization: 6.5
• Atomic Radius: Unknown

22. Mendelevium
• Symbol: Md
• Atomic Number: 101
• Atomic Mass: (258)
• Electron Configuration: [Rn] 5f13 7s2
• Number of Electrons/Shells: 2,8,18,32,31,8,2
• Boiling Point: Unknown
• Melting Point: 1100 K
• 1st Ionization: 6.58
• Atomic Radius: Unknown

23. Nobelium
• Symbol: No
• Atomic Number: 102
• Atomic Mass: (259)
• Electron Configuration: [Rn] 5f14 7s2
• Number of Electrons/Shells: 2,8,18,32,32,8,2
• Boiling Point: Unknown
• Melting Point: 1100 K
• 1st Ionization: 6.65
• Atomic Radius: Unknown

24. Lawrencium
• Symbol: Lr
• Atomic Number: 103
• Atomic Mass: (262)
• Electron Configuration: [Rn] 5f14 7s2 7p1
• Number of Electrons/Shells: 2,8,18,32,32,8,3
• Boiling Point: Unknown
• Melting Point: 1900 K
• 1st Ionization: 4.9
• Atomic Radius: Unknown

25. Rutherfordium
• Symbol: Rf
• Atomic Number: 104
• Atomic Mass: (261)
• Electron Configuration: [Rn] 5f14 6d2 7s2
• Number of Electrons/Shells: 2,8,18,32,32,10,2
• Boiling Point: Unknown
• Melting Point: Unknown
• 1st Ionization: Unknown
• Atomic Radius: Unknown

26. Dubnium
• Symbol: Db
• Atomic Number: 105
• Atomic Mass: (262)
• Electron Configuration: [Rn] 5f14 6d3 7s2
• Number of Electrons/Shells: 2,8,18,32,32,11,2
• Boiling Point: Unknown
• Melting Point: Unknown
• 1st Ionization: Unknown
• Atomic Radius: Unknown

27. Seaborgium
• Symbol: Sg
• Atomic Number: 106
• Atomic Mass: (263)
• Electron Configuration: [Rn] 5f14 6d4 7s2
• Number of Electrons/Shells: 2,8,18,32,32,12,2
• Boiling Point: Unknown
• Melting Point: Unknown
• 1st Ionization: Unknown
• Atomic Radius: Unknown

28. Bohrium
• Symbol: Bh
• Atomic Number: 107
• Atomic Mass: (262)
• Electron Configuration: [Rn] 5f14 6d5 7s2
• Number of Electrons/Shells: 2,8,18,32,32,13,2
• Boiling Point: Unknown
• Melting Point: Unknown
• 1st Ionization: Unknown
• Atomic Radius: Unknown

29. Hassium
• Symbol: Hs
• Atomic Number: 108
• Atomic Mass: (265)
• Electron Configuration: [Rn] 5f14 6d6 7s2
• Number of Electrons/Shells: 2,8,18,32,32,14,2
• Boiling Point: Unknown
• Melting Point: Unknown
• 1st Ionization: Unknown
• Atomic Radius: Unknown

30. Meiternium
• Symbol: My
• Atomic Number: 109
• Atomic Mass: (266)
• Electron Configuration: [Rn] 5f14 6d7 7s2
• Number of Electrons/Shells: 2,8,18,32,32,15,2
• Boiling Point: Unknown
• Melting Point: Unknown
• 1st Ionization: Unknown
• Atomic Radius: Unknown

31. Group 18 Trends
• Atomic mass, boiling point and atomic radii INCREASE down a group in the periodic table.
• The first ionization energy, DECREASES down a group in the periodic table.
• The noble gases have the largest ionization energies which reflects their chemical inertness.
• As you go down group 18, atomic radius and inter-atomic forces INCREASES resulting in
an INCREASED melting point, boiling point, enthalpy of vaporization and solubility.
• Group 18's INCREASE in density is correlated to the INCREASE in atomic mass.
• Because noble gases’ outer shell is full, they are extremely stable, not tending to form
chemical bonds and have a low tendency to gain or lose electrons.
• Noble gas atoms, like other atoms in other groups, INCREASE steadily in atomic radius from
one period to the next due to the INCREASING number of electrons.
• The size of the atom is positively correlated to several properties of noble gases. The
ionization potential DECREASES with an INCREASING radius, because the valence electrons in
the larger noble gases are further away from the nucleus, so they are not being held as
tightly together by the atom.
• The attractive force INCREASES with the size of the atom as a result of an INCREASE in
polarizability and thus a DECREASE in ionization potential.
• Overall, noble gases have weak interatomic forces, and therefore very low boiling and
melting points compared to other group elements.
• Electron affinity DECREASES from top to bottom within a group. This is caused by the
increase in atomic radius.

32. Period 7 Trends
• s you move across a period, electron affinity increases.
• As you move across a period, first ionization energy increases.
• Cations (positive ions) are smaller than their respective atoms.
• Anions (negative ions) are larger than their respective atoms.
• As you move across a period, atomic radius decreases.