School Science Lessons
2026-02-23
Elements, Actinium to Zirconium
Table 1. Periodic Table
Table 2. Terms applied to the Table of the Elements
Elements, Actinium to Zirconium
Contents
Table 1. Periodic Table
See: Periodic table, An official website of the United States government
Terms applied to the Periodic Table:
Actinides, actinoids: 2.1.0
Alkali metals, Group 1: 1.1.0
Alkaline earth metals, Group 2: 1.2.0
Common or industrial classification of metals: 1.3.0
Base metals: 1.3.1
Coinage metals: 1.3.2
Noble metals: 1.3.3
Precious metals: 1.3.4
Electronegativity: 1.4.0
Groups: 1.5.0
Halogens, Group 17: 12.0
Noble gases: 1.9.0
Introduction to the periodic table: 1.10.1
Patterns in the periodic table: 1.10.2
Periods: 1.11.0
Transition elements: 1.12.0
Transuranic elements have atomic number > 92
Table 1. Periodic table
G = Groups
P1 to P7 = Periods
P6a = Lanthanides
P7a = Actinides
G
|
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
13 |
14 |
15 |
16 |
17 |
18
|
P2
P2
|
03
Li |
04
Be |
. |
. |
. |
. |
. |
. |
. |
. |
. |
. |
05
B |
06
C |
07
N |
08
O |
09
F |
10
Ne |
P3
P3
|
11
Na |
12
Mg |
. |
. |
. |
. |
. |
. |
. |
. |
. |
. |
13
Al |
14
Si |
15
P |
16
S |
17
Cl |
18
Ar |
P4
P4
|
19
K |
20
Ca |
21
Sc |
22
Ti |
23
V |
24
Cr |
25
Mn |
26
Fe |
27
Co |
28
Ni |
29
Cu |
30
Zn |
31
Ga |
32
Ge |
33
As |
34
Se |
35
Br |
36
Kr |
P5
P5
|
37
Rb |
38
Sr |
39
Y |
40
Zr |
41
Nb |
42
Mo |
43
Tc |
44
Ru |
45
Rh |
46
Pd |
47
Ag |
48
Cd |
49
In |
50
Sn |
51
Sb |
52
Te |
53
I |
54
Xe |
P6
P6
|
55
Cs |
56
Ba |
71
Lu
|
72
Hf |
73
Ta |
74
W |
75
Re |
76
Os |
77
Ir |
78
Pt |
79
Au |
80
Hg |
81
Tl |
82
Pb |
83
Bi |
84
Po |
85
At |
86
Rn |
P7
P7
|
87
Fr |
88
Ra |
103
Lw
|
104
Rf |
105
Db |
106
Sg |
107
Bh |
108
Hs |
109
Mt |
110
Ds |
111
Rg |
112
Cn
|
. |
Fl
|
. |
116
Lv
|
. |
. |
P6a
P6a
|
.
|
.
|
57
La
|
58
Ce
|
59
Pr
|
60
Nd
|
61
Pm
|
62
Sm
|
63
Eu
|
64
Gd
|
65
Tb
|
66
Dy
|
67
Ho
|
68
Er
|
69
Tm
|
70
Yb
|
71
Lu
|
.
|
P7a
P7a
|
.
|
.
|
89
Ac
|
90
Th
|
91
Pa
|
92
U
|
93
Np
|
94
Pu
|
95
Am
|
96
Cm
|
97
Bk
|
98
Cf
|
99
Es
|
100
Fm
|
101
Md
|
102
No
|
103
Lr
|
.
|
Group 1, Alkali metals
Alkali metals: Lithium, Li, Sodium, Na, Potassium, K, Rubidium, Rb, Caesium, Cs, Francium, Fr
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.
1.2.0 Group 2, Alkaline earth 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. Mg 2+.
1.3.0 Common or industrial classification of metals
In the common or industrial classification of metals, the following descriptions of metals are not chemically exact terms:
1.3.1 Base metals
Base metals are neither noble nor precious, are not resistant to oxidation, are common and are readily available with many uses,
including Aluminium, Copper, Lead, Nickel, Tin and Zinc.
1.3.2 Coinage metals
Coinage metals are copper, gold and silver, but this description of metals is not a chemically exact term.
Nordic Gold, a gold-coloured alloy, often used in coins, is made of 89% copper, 5% aluminium, 5% zinc, and 1% tin.
1.3.3 Noble metals
Noble metals are commonly only Gold and Silver, but also can refer to metallic chemical elements resistant to oxidation or corrosion,
including: Ruthenium, Rhodium, Palladium, Silver, Rhenium, Osmium, Iridium, Platinum, and Gold,
i.e. of the second and third transition series of the Periodic Table.
1.3.4 Precious metals
Precious metals are those usually used in jewellery including Gold, Iridium, Palladium, Platinum, and Silver.
1.4.0 Electronegativity
Electronegativity is based on the IUPAC electronegativity list
Electronegativity is the degree to which an atom attracts electrons.
Ignoring lanthanides and actinides, for two elements in different groups, the element in the higher numbered group has higher electronegativity.
For two elements within the same group, the element with the lower the atomic number has the higher electronegativity.
Hydrogen is less electronegative than polonium and more electronegative than nitrogen, so the formula of water is H2O and the formula of ammonia is NH3 .
List of highest to lowest electronegativity
Group 17, F to At
Group 16, O to Po
H, hydrogen,
Group 15, N to Bi
Group 14, C to Pb
Group 13, B to Tl
Group 12, Zn to Cn
Group 11, Cu to Rg
Group 10, Ni to Ds
Group 9, Co to Mt
Group 8, Fe to Hs
Group 7, Mn to Bh
Group 6, Cr to Sg
Group 5, V to Db
Group 4, Ti to Rf
Group 3, Sc to La
Lanthanides, La to Lu
Actinides, Ac to Lr
Group 2, Be to Ra
Group 1 (excluding H), Li to Fr
Group 18, He to Rn
1.5.0 Groups
Groups are the arrangement of elements in the periodic table.
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 roperties, 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.
1.6.0 Group 17
Halogens, At, Br, Cl, F, I
Group 17 elements are the halogens, F, Cl, Br, I, At.
1.7.0 Heavy elements
IUPAC has approved these new heavy elements, 114 Fl (Flerovium) and 116 Lv (Livermorium) (1 June 2012).
1.9.0 Noble gases
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.
1.10.0 Periodic table
1.10.1 Introduction to the periodic table
The periodic table organizes elements and it can be used to make predictions about the properties of elements.
The periodic table is an orderly way to arrange the properties of the elements.
The periodic table shows each element as a symbol with its atomic number atomic mass (whole number) electron notation and valence.
The groups have group notation numbers, 1 to 18, as approved by the IUPAC (International Union of Pure and Applied Chemistry).
The atomic number is shown above the symbol for each element.
It is equal to the number of protons in the nucleus.
The relative atomic mass is shown below the symbol for each element.
It is the average of the values for the different isotopes of the element.
The relative atomic mass of Carbon, C, is defined as Metallic properties are dominant towards the lower left corner and non-metallic properties
are dominant towards the upper right corner.
Periods and groups for the first 20 elements: group (vertical), period (horizontal).
In the full periodic table, Groups 3 to 12 contain the transition elements including:
| 4th Period: Mn, Fe, Co, Ni, Cu, Zn,
| 5th period: Mo, Ag, Cd, Sn | 6th period Pt, Au, Hg, Bi.
Table 12.19.10
| Group |
1 |
2 |
3 |
4 |
5 |
6 |
17 |
18 |
| 1st period |
H |
. |
.
|
.
|
. |
.
|
.
|
He |
| 2nd period |
Li |
Be |
B |
C |
N |
O |
F |
Ne |
| 3rd period |
Na |
Mg |
Al |
Si |
P |
S |
Cl |
Ar |
| 4th period |
K |
Ca |
.
|
. |
.
|
.
|
.
|
. |
Activity
1.10.2 Patterns in the periodic table
Use A4 size periodic charts for student use or a classroom size 2 000 ×1 500 mm periodic chart to find the following information
and fill in a blank A4 size chart of the periodic table.
Commercial: Periodic table chart, A4 sheet, three colour, pad of 100 sheets
Commercial: Sargent-Welch three colour poster size, laminated chart with metal eyelets, double sided, in protective cardboard tube,
130 cm × 90 cm and 495 mm × 694 mm
1. Periods: The elements have electrons in the same outer shell, i.e. the rows.
2. Groups: The elements have the same number of electrons in their outer shells, i.e. the columns.
A group of elements has similar chemical properties.
3. Metals: Al and elements below and to left of Al and Sn, Pb (Sb, Bi) Po, but not H.
4. Non-metals: He, C, N, O, F, Ne, P, S, Cl, Ar, Se, Br, Kr, I, Xe, At, and Rn.
5. Metalloids: As, Ge, Si, Te (and Sb, Bi, B).
6. Elements that are gases at room temperature, 27 oC: H2, He, N2, O2, Ne, Cl2, Ar, Kr, Xe and Rn.
The elements that are liquids at room temperature are Hg and Br.
3. Periodic variations
Elements 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 are 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,
Metals usually have a few valences, but Bismuth, Lead and Tin have many valences.
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, e.g. mercury, Hg, is liquid at room temperature.
1.11.0 Periods
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.
Period 1: 1 H and 2 He
Period 2: 3 Li to 10 Ne
Period 3: 11 Na to 18 Ar
Note the important trends in the reactions of the Period 3 compounds from metals on the left to non-metals on the right, e.g. reactions of the oxides and chlorides with water
Period 4: 19 K and 20 Ca, and 31 Ga to 36 Kr
Period 5: 37 Rb and 38 Sr, and 49 In to 54 Xe
Period 6: 55 Cs and 56 Ba, and 81 Ti to 86 Rn
Period 7: 87 Fr, 88 Ra, 89 Ac
Period 6a: 57 La to 71 Lu (Lanthanides)
Period 7a: 89 Ac to 103 Lr Actinides
1.12.0 Transition elements
Groups 3 to 12, periods 4 and 5
Period 4: | Scandium | Titanium | Vanadium
| Chromium | Manganese
| Iron | Cobalt
| Nickel | Copper
| Zinc
Period 5: Yttrium | Zirconium | Niobium
| Molybdenum | Technetium
| Ruthenium | Rhodium
| Palladium | Silver
Transition metals (transition elements) have atomic numbers as follows:
Group 3 to Group 12
First transition series: 21 Sc to 30 Zn,
Second transition series: 39 Y to 48 Cd,
Third transition series 57 La to 80 Hg.
(Some chemists refer to Zn, Cd and Hg as metals, not transition metals.)
The transition elements are good conductors of heat and electricity, hard, strong, shiny, high mp and bp.
Only Hg is liquid at room temperature.
With these properties they are useful a pure substances, because of their relatively low chemical activity, e.g. Fe and Cu.
Transition metals have more than one oxidation states in their compounds, e.g. Cu (I) Cu 2 O, Cu (II) CuO,
most are coloured, most are catalysts and many form complex ions, e.g. [Cu(H 2 O) 6 ] 2+, when copper sulfate dissolves in water.
Table 2. Terms applied to the Table of the Elements:
Contents
Actinides, actinoids: 2.1.0
Atomic mass units, amu: 2.4.0
Atomic number and mass number: 2.2.0
Atomic weight: 2.3.0
Atomic weight elements with no stable isotopes
Elements: 2.5.0
Free element metals: 2.6.0
Heavy metals: 2.7.0
Lanthanides: 2.11.0
Metalloids: 2.8.0
Radiation: 2.9.0
Radioactive carbon dating: 2.10.1
Radioactive elements: 2.10.0
Rare earth elements: 2.11.0
Symbol of an element: 2.12.0
Table of the elements
2.1.0 Actinides, actinoids
Actinoids, rare earth elements, from 89 Ac, to 103 Lr inclusive, are metals shown separately below the main table, in periodP7a.
Actinides can be represented by Ac.
The valence of their cations varies.
They are all radioactive.
They form part of the group of transition metals.
| Actinium
| Thorium
| Protactinium
| Uranium
| Neptunium
| Plutonium
| Americium
| Curium
| Berkelium
| Californium
| Einsteinium
| Fermium
| Mendelevium
| Nobelium
| Lawrencium |
2.2.0 Atomic number and mass number
Atomic number, Z, is the number of protons in the nucleus of an atom of an element.
Mass number, A, atomic mass number, nucleon number, is the total number of protons and neutrons in the nucleus of an atom of an element.
Atomic number is shown in the left subscript position and mass number is shown in the left superscript position.
See diagram 2.2.0: Carbon-12, Uranium-238, Oxygen-16
2.3.0 Atomic weight
Atomic weight, relative atomic mass (r.a.m.), of an element, is the ratio of the average atomic mass of an atom of an element, including the common isotopes,
to 1/12 the mass of an atom of carbon-12, the unified atomic mass unit.
Awt, Elements with no stable isotopes
Chlorine is 75% chlorine-35 and 25% chlorine-37, r.a.m. = 35.4527, so atomic weight is usually quoted as 35.5.
For atomic weight values listed for elements with no stable isotopes. See IUPAC Periodic Table of the Elements, 2011-01-21.
2.4.0 Atomic mass units, amu
Atomic mass units (u) are used to state the mass of an individual particle, e.g. 1 atom of oxygen has a mass of 16.00 u.
The atomic mass unit is 1/12 of the mass of 12 C. Mass of 1 amu = 1.66 × 10 −27 kg.
2.5.0 Elements
Elements, chemical elements, are substances that cannot be separated into simpler substances.
All matter consists of single elements or combinations of elements.
The periodic table includes 92 naturally occurring elements and 8 or more radioactive elements synthesized by nuclear reactions.
2.6.0 Free element metals
Free element metals are found in free elemental form, e.g. Gold | Copper.
2.7.0 Heavy metals
3.10.0 Poisons and First Aid (Table)
Heavy metals, a metal of relatively high density, specific gravity > 5, metal of high relative atomic weight, especially if poisonous.
The term "heavy metals" has been used in legislation related to chemical hazards and the safe use of chemicals with the legal regulations
in specifying a list of heavy metals to which they apply.
Heavy metals, defined as elements commonly used in industry and generically toxic to animals and to aerobic and anaerobic processes,
may include As, Cd, Cr, Cu, Pb, Hg, Ni, Se, Zn.
| Copper
| Lead
| Mercury
| Zinc | are called "heavy metals", if they cause pollution.
The term "heavy metal" is not exact.
For example, although Aluminium and Beryllium are toxic, they are not called heavy metals.
2.8.0 Metalloids
Metalloids have properties between metals and non-metals.
The metalloids are as follows:
| Boron
| Silicon
| Germanium
| Arsenic
| Antimony
| Tellurium |
Also some chemists include:
| Polonium
| and | Astatine. |
2.9.0 Radiation
Radiation, ionizing radiation, Geiger counter
See diagram 2.9: Geiger counter
Alpha particles have two protons and two neutrons, Helium nucleus.
Beta particles are electrons.
Gamma rays and X-rays are pure photons.
A Geiger counter is used to detect alpha particles, beta particles and gamma rays.
A radionuclide (radioisotope, isotope), emits radioactivity, gamma rays and may be used in nuclear medicine.
The five types of ionizing radiation
1. Alpha radiation
Alpha radiation, α radiation + alpha particle
Uranium -238 --> thorium-234
238 U 92 --> 234 Th 90 + 4 He 2 + energy
An alpha particle can be shown as 4 He 2 or 4 α 2.
uranium-238 -->; thorium-234 + alpha particle + gamma rays (gamma photon)
Uranium, symbol U, atomic number 92, is in group 6, period P7a of the Periodic Table.
Alpha radiation travels a very short distance through air, cannot penetrate skin or clothing,
but it can be harmful if alpha-emitting materials inhaled, swallowed, or absorbed through open wounds.
Transuranic elements, have atomic number >; 92
2. Beta radiation
Beta radiation, β radiation
Carbon-14 --> nitrogen-14 + beta particle + antineutrino
14 C 6 --> 14 N 7 + 0 β -1 + electron antineutrino ( ̅νe) + energy
Some useful Beta emitters:
Phosphorous-32,
Tritium (H-3),
Carbon-14,
Strontium-90, and Lead-210.
3. Gamma radiation
Gamma radiation, γ radiation
Iodine-131 --> xenon 131 + gamma ray + beta particle
131 I5 3 --> 131 Xe 54 + 0 β -1 + 0 γ 0
The three most useful gamma radionuclides are:
Cobalt-60, Cesium-137, Technetium-99m.
4. X- rays
See27.23
5. Ultraviolet rays
Ultraviolet radiation (UV):
See 27.24
Ionizing radiation only wavelengths < 200 nm (called Vacuum UV or VUV), occurs in the atmosphere
Absorbed dose of ionizing radiation = energy absorbed / mass of tissue = J / kg, Grays (Gy)
Dose equivalent = absorbed dose × quality factor, Sieverts (Sv).
Quality factor is the comparative ionizing effect of radiation
Quality factors:
Alpha particles 20,
Neutrons >10 k3V 10 (only from nuclear reactions or neutron bombs),
Beta particles 1, Gamma rays 1, X-rays 1.
Background radiation comes from:
Space radiation, e.g. cosmic rays at high altitude, terrestrial radiation,
Rocks,
Radon-220, ingested thorium, potassium-40, manufactured radiation, coal power stations, medical treatment, e.g. X-rays.
2.10.0 Radioactive element, stable isotope, half life
By Todd Helmenstine
| Technetium Tc-91, 4.21 x 106 years |
Promethium Pm-145, 17.4 years |
Polonium Po-209, 102 years |
Astatine At-210, 8.1 hours |
Radon Rn-222, 3.82 days |
Francium Fr-223, 22 minutes |
Radium Ra-226, 1600 years |
Actinium Ac-227, 21.77 years |
Thorium Th-229, 7.54 x 104 years |
Protactinium Pa-231, 3.28 x 104 years |
Uranium U-236, 2.34 x 107 years |
Neptunium Np-237, 2.14 x 106 years |
Plutonium Pu-244, 8.00 x 107 years |
Americium Am-243, 7370 years |
Curium Cm-247, 1.56 x 107 years |
Berkelium Bk-247, 1380 years |
Californium Cf-251, 898 years |
Einsteinium Es-252, 471.7 days |
Fermium Fm-257, 100.5 days |
Mendelevium Md-258, 51.5 days |
Nobelium No-259, 58 minutes |
Lawrencium Lr-262, 4 hours |
Rutherfordium Rf-265, 13 hours |
Dubnium Db-268, 32 hours |
Seaborgium Sg-271, 2.4 minutes |
Bohrium Bh-267, 17 seconds |
Hassium Hs-269, 9.7 seconds |
Meitnerium Mt-276, 0.72 seconds |
Darmstadtium Ds-281, 11.1 seconds |
Roentgenium Rg-281, 26 seconds |
Copernicium Cn-285, 29 seconds |
Ununtrium Uut-284, 0.48 seconds |
Flerovium Fl-289, 2.65 seconds |
Ununpentium Uup-289, 87 milliseconds |
Livermorium Lv-293, 61 milliseconds |
2.10.1 Radioactive carbon dating
The radioactive isotope of carbon 14 C has half-life 5700 years.
The most abundant carbon isotope is 12 C and ratio of 12 C / 14 C in the environment is constant enough in the environment
and so in the tissues of living organisms.
At the death of an organism, the amount of 14 C decays exponentially, so the age of a fossil organism can be estimated by
comparing its 12 C / 14 C ratio with the current value.
No carbon dating can be done for after 1950, because of contamination of the atmosphere by nuclear explosions.
2.11.0 Rare earth elements, Lanthanides
#P6aH">Lanthanides rare earth elements (rare earth metals), atomic numbers 57 La * to 71 Lu, are 15 metals shown separately below in the Periodic table, period P6a.
They are all named after where they were originally found in Sweden.
The "rare earths" are not "rare"!
If Lanthanides are represented by Ln, they all form trivalent cations Ln 3+.
| Lanthanum
| Cerium
| Praseodymium
| Neodymium
| Promethium
| Samarium
| Europium
| Gadolinium
| Terbium
| Dysprosium
| Holmium
| Erbium
| Thulium
| Ytterbium
| Lutetium |
The IUPAC adds Scandium, Sc, and Yttrium, Y, to the list of rare earth elements,
because they have similar chemical properties and are often found in the same ores as the lanthanides.
| Scandium
| Yttrium |
2.12.0 Symbol of an element
Symbol of an element, e.g. H for Hydrogen.
Atomic symbols, chemical formula notation, e.g. Ac, were mainly invented by the Swedish chemist Jacob Berzelius, (1779-1848).