School Science Lessons
2012-05-02 SPP
Please send comments to: J.Elfick@uq.edu.au
Table 1. Periodic table
See also: Table 2. Table of elements
Order online: Periodic Table of the Elements
Atomic number
Groups
Periods
Lanthanoids (lanthanide series)
Actinoids (actinide series)
Transition metals (transition elements)
Periods |................................................................Groups......................................................................
.
 1.
 2.
 3.
 4.
 5.
 6.
 7.
 8.
 9.
 10
 11
 12
 13
 14
 15
 16
 17
 18
.
 01
 .
 .
 .
 .
 .
 .
 .
 .
 .
 .
 .
 .
 .
 .
 .
 .
 02
1
 H . . . . . . . . . . . . . .
 .
 . He
.
 03
 04
 .
 .
 .
 .
 .
 .
 .
 .
 .
 .
 05
 06
 07
 08
 09
 10
2
 Li Be . . . . . . . . . . B C N O F Ne
.
 11 12 . . . . . . . . . . 13 14 15 16 17 18
3
 		Na Mg . . . . . . . . . . Al Si P S Cl Ar
.
 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36
4
 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
.
 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
5
 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
.
 55 56 57* 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86
6
 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Ti Pb Bi Po At Rn
.
 87 88 89* 104 105 106 107 108 109 110 111 112
 . 114 . 116 . .
7
 Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg Cn
 . . . . . .
.
 .
 58 59 60 61 62 63 64 65 66 67 68 69 70 71 .
 .
 .
6a
 .
 Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu .
 .
 .
.
 .
 90 91 92 93 94 95 96 97 98 99 100 101 102 103 .
 .
 .
7a
 .
 Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lw ......
 ......
 .......
114 and 116, IUPAC has approved these new heavy elements, as yet not named (2011-06-14).
Atomic number is shown in the cell above the symbol for the element.
So oxygen, symbol O, atomic number 8, is in group 16, period 2.
Groups
The periodic table has the elements arranged in groups. Some periodic tables using 1a, 2a to 0, suggest
there are 18 groups. Other versions have only 8 or 9 groups. Elements in the same group in the periodic
table have similar chemical properties: because they have the same number of electrons in their outer
shells. (This is not true if you group the transition elements together in the table.) Groups are shown as
vertical columns numbered 1 to 18, see top row. The newest element is Copernicum, Cn, atomic number
112, discovered in 1996, but not given its symbol, Cn, by IUPAC until 2010.
Group 1 elements include the alkali metals, Li, Na, K, Rb, Cs, Fr. The alkali metals are all soft, shiny
and metallic when cut. They react easily with water, have low melting points and densities, and are good
conductors of electricity. They all have one valence electron that they lose easily to form ions. Hydrogen
is considered separately because it has few of the properties: of the alkali metals.
Group 2 elements are the alkaline earth metals, Be, Mg, Ca, Sr, Ba, Ra. They are harder and have
higher melting points and boiling points than the alkali metals. They easily lose two electrons to form ions,
e.g. Mg2+.
Group 17 elements are the halogens, F, Cl, Br, I, At. Astatine has the longest life of any radioactive
isotope.
Group 18 elements are the noble gases (inert gases or rare gases) He, Ne, Ar, Kr, Xe, Rn-222. They
are colourless, odourless, monatomic gases and they form very few compounds.
Periods are shown as horizontal rows numbered 1 to 7, in italics, see far left
column. The elements in a period have electrons in the same outer shell.
First period: 1 H and 2 He
Second period: 3 Li to 10 Ne
Third period: 11 Na to 18 Ar
Fourth period: 19 K and 20 Ca, and 31 Ga to 36 Kr
Fifth period: 37 Rb and 38 Sr, and 49 In to 54 Xe
Sixth period: 55 Cs and 56 Ba, and 81 Ti to 86 Rn
Seventh period: 87 Fr, 88 Ra, 89 Ac
Periodic variations
From theory of electronic structure it is predicted that elements will display
periodic variations in their chemical and physical properties:
1. the trends across a period or down a group in the periodic table for
properties, e.g. melting or boiling point, reactivity, ionization energy, atomic
radius, metallic character, nature of oxides;
2. the terms used to describe groups and periods of the periodic table; alkali
metals, alkali earth metals, halogens, noble gases, lanthanides and actinides;
3. the relationship between the number of valence electrons for an element,
its position in the periodic table, and its chemical properties;
4. the properties of an element, e.g. combining power, general reactivity, and
relationship to its position in the periodic table;
5. anomalies in the properties of an element.
Lanthanoids (lanthanide series) atomic numbers 58 Ce* to 71 Lu are
shown separately below the main table, period 6a . They are also called rare earth elements.
Actinoids, (actinide series) atomic numbers 90 Th* to 103 Lw, are shown
separately below the main table, period 7a. The lanthanoids and actinoids are metals.
So the lanthanoid uranium, symbol U, atomic number 92, is in group 4, period 7.
Transition metals (transition elements) have atomic numbers as follows:
First transition series: 21 Sc to 30 Zn,
Second transition series: 39 Y to 48 Cd,
Third transition series 57 La to 80 Hg. However, some chemists refer to Zn, Cd
and Hg as metals, not transition metals.