Doc Brown's Advanced Level Inorganic Chemistry Periodic Table Revision Notes

 Part 2 Electronic Structure, Spectroscopy & Ionisation Energies

Electron Configurations of Elements

Sections 2.3 Electron configurations for elements of atomic number Z = 1 to 56

Part 2.3 uses the rules on assigning electron arrangements, and how the quantum level notation is written out, and using boxes to represent orbitals, is given for elements Z = 1 to 56

2.4 The relationship between electron configuration and the Periodic Table

Part 2.4 uses the electron configurations to show how the Periodic Table arises, i.e. an element's position in the Periodic Table and hence its chemistry, is primarily determined by the arrangement of its outer valency electrons.

2.5 The electron configuration of ions and oxidation states

Part 2.5 shows how to work out the configuration of ions, (positive cations or negative anions formed by the loss or gain of valence electrons), and also, relating electron arrangements to the oxidation states exhibited by selected elements.

GCSE/IGCSE/AS Atomic Structure Notes  *  GCSE/IGCSE Periodic Table notes

INORGANIC Part 2 sub-index: 2.1 The electronic basis of the modern Periodic Table * 2.2 The electronic structure of atoms (including s p d f subshells/orbitals/notation) * 2.3 Electron configurations of elements (Z = 1 to 56) * 2.4 Electron configuration and the Periodic Table * 2.5 Electron configuration of ions and oxidation states * 2.6 Spectroscopy and the hydrogen spectrum * 2.7 Evidence of quantum levels from ionisation energies

Advanced Level Inorganic Chemistry Periodic Table Index * Part 1 Periodic Table history * Part 2 Electron configurations, spectroscopy, hydrogen spectrum, ionisation energies * Part 3 Period 1 survey H to He * Part 4 Period 2 survey Li to Ne * Part 5 Period 3 survey Na to Ar * Part 6 Period 4 survey K to Kr and important trends down a group * Part 7 s-block Groups 1/2 Alkali Metals/Alkaline Earth Metals * Part 8  p-block Groups 3/13 to 0/18 * Part 9 Group 7/17 The Halogens * Part 10 3d block elements & Transition Metal Series * Part 11 Group & Series data & periodicity plots * All 11 Parts have their own sub-indexes near the top of the pages

 2.3 List of the Electronic Configuration of Elements 1 to 56 using the advanced notation

YOU MUST STUDY Parts 2.1 and 2.2 before studying 2.3 - The rules of how to assign electrons in multi-electron atoms to the appropriate quantum levels were explained in section 2.2. The list below quotes the ground state electron configurations i.e. the lowest available state according to the Aufbau principle (previously described).

Electron Box diagrams of the outer electron arrangement and examples of the simple electron notation (e.g. 2.8.1) are also included, with brief comments in the end right hand column e.g. element symbol, group, series etc. The electrons-in-boxes notation for subshells: Boxes are used to represent an individual orbital or set of orbitals in the electrons are shown as arrows. The pairs up/down arrows represent a full orbital with electrons of opposite spin and note how the half-filled boxes/orbitals illustrate Hund's rule of maximum multiplicity.

The energy level filling order up to Z = 56 is 1s 2s 2p 3s 3p 4s 3d 4p (for Z = 1 to 36) 5s 4d 5p 6s 4f/5d? (for Z = 37 to 56)

However, when writing out the electron configuration you must write them out in order of strict principal quantum with the accompanying s, p, d, f notation i.e. the order 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 6s (upto Z = 58)

Atomic number Z and the element name and symbol	Electron configuration s, p, d & f notation with electron number superscripts (plus some simplified electron arrangements)	Box diagram of outer electron orbitals representing the superscripted electrons beyond the inner noble gas core [He/Ne/Ar/Kr], the latter are not involved in chemical bonding/reactions.	Symbol, group/series/block and Comments
1 Hydrogen, H	1s1	1s	H, no Gp really, a bit unique!
2 Helium, He	1s2 = [He]	1s very stable	He, Gp 0/18 Noble Gas,
3 Lithium, Li	1s22s1 (simple notation: 2.1)	[He]2s2p	Li, s-block, Gp1 Alkali Metal,
4 Beryllium, Be	1s22s2 (2.2)	[He]2s2p	Be, s-block, Gp2 Alkaline Earth Metal,
5 Boron, B	1s22s22p1 (2.3)	[He]2s2p	B, p-block, Gp3/13
6 Carbon, C	1s22s22p2 (2.4)	[He]2s2p	C, p-block, Gp4/14,
7 Nitrogen, N	1s22s22p3 (2.5)	[He]2s2p	N, p-block, Gp5/15,
8 Oxygen, O	1s22s22p4 (2.6)	[He]2s2p	O, p-block, Gp6/16,
9 Fluorine, F	1s22s22p5 (2.7)	[He]2s2p	F, p-block, Gp7/17 Halogen,
10 Neon, Ne	1s22s22p6 = [Ne] (2.8)	[He]2s2p very stable	Ne, p-block, Gp 0/18 Noble Gas,
11 Sodium, Na	1s22s22p63s1 (2.8.1)	[Ne]3s3p	Na, Gp1 Alkali Metal,
12 Magnesium, Mg	1s22s22p63s2 (2.8.2)	[Ne]3s3p	Mg, s-block, Gp2 Alkaline Earth Metal,
13 Aluminium, Al	1s22s22p63s23p1 (2.8.3)	[Ne]3s3p	Al, p-block, Gp3/13,
14 Silicon, Si	1s22s22p63s23p2 (2.8.4)	[Ne]3s3p	Si, p-block, Gp4/14,
15 Phosphorus, P	1s22s22p63s23p3 (2.8.5)	[Ne]3s3p	P, p-block, Gp5/15,
16 Sulphur, S	1s22s22p63s23p4 (2.8.6)	[Ne]3s3p	S, p-block, Gp6/16,
17 Chlorine, Cl	1s22s22p63s23p5 (2.8.7)	[Ne]3s3p	Cl, p-block, Gp7/17 Halogen,
18 Argon, Ar	1s22s22p63s23p6 = [Ar] (2.8.8)	[Ne]3s3p very stable	Ar, p-block, Gp 0/18 Noble Gas,
19 Potassium, K	1s22s22p63s23p64s1 (2.8.8.1)	[Ar]3d4s4p	K, s-block, Gp1 Alkali Metal,
20 Calcium, Ca	1s22s22p63s23p64s2 (2.8.8.1)	[Ar]3d4s4p	Ca, s-block, Gp2 Alkaline Earth Metal,
21 Scandium, Sc	1s22s22p63s23p63d14s2	[Ar]3d4s4p	Sc, 3d block, not true Transition Metal
22 Titanium, Ti	1s22s22p63s23p63d24s2	[Ar]3d4s4p	Ti, 3d block, a true Transition Metal
23 Vanadium, V	1s22s22p63s23p63d34s2	[Ar]3d4s4p	V, 3d block, a true Transition Metal
24 Chromium, Cr	1s22s22p63s23p63d54s1	[Ar]3d4s4p	Cr, 3d block, a true Transition Metal
25 Manganese, Mn	1s22s22p63s23p63d54s2	[Ar]3d4s4p	Mn, 3d block, a true Transition Metal
26 Iron, Fe	1s22s22p63s23p63d64s2	[Ar]3d4s4p	Fe, 3d block, a true Transition Metal
27 Cobalt, Co	1s22s22p63s23p63d74s2	[Ar]3d4s4p	Co, 3d block, a true Transition Metal
28 Nickel, Ni	1s22s22p63s23p63d84s2	[Ar]3d4s4p	Ni, 3d block, a true Transition Metal
29 Copper, Cu	1s22s22p63s23p63d104s1	[Ar]3d4s4p	Cu, 3d block, a true Transition Metal
30 Zinc, Zn	1s22s22p63s23p63d104s2	[Ar]3d4s4p	Zn, 3d block, not true Transition Metal
31 Gallium, Ga	[Ar]3d104s24p1	[Ar]3d4s4p	Ga, p-block, Gp3/13,
32 Germanium, Ge	[Ar]3d104s24p2	[Ar]3d4s4p	Ge, p-block, Gp4/14,
33 Arsenic, As	[Ar]3d104s24p3	[Ar]3d4s4p	As, p-block, Gp5/15,
34 Selenium, Se	[Ar]3d104s24p4	[Ar]3d4s4p	Se, p-block, Gp6/16,
35 Bromine, Br	[Ar]3d104s24p5	[Ar]3d4s4p	Br, p-block, Gp7/17 Halogen,
36 Krypton, Kr	[Ar]3d104s24p6 = [Kr] (2.8.18.8)	[Ar]3d4s4p v. stable	Kr, p-block, Gp 0/18 Noble Gas,
37 Rubidium, Rb	[Kr]5s1	[Kr]5s	Rb, s-block, Gp1 Alkali Metal,
38 Strontium, Sr	[Kr]5s2	[Kr]5s	Sr, s-block, Gp2 Alkaline Earth Metal,
39 Yttrium, Y	[Kr]4d15s2	[Kr]4d5s	Y, 4d block, not true Transition Metal
40 Zirconium, Zr	[Kr]4d25s2	[Kr]4d5s	Zr, 4d block, a true Transition Metal
41 Niobium, Nb	[Kr]4d45s1	[Kr]4d5s	Nb, 4d block, a true Transition Metal
42 Molybdenum, Mo	[Kr]4d55s1	[Kr]4d5s	Mo, 4d block, a true Transition Metal
43 Technetium, Tc	[Kr]4d55s2	[Kr]4d5s	Tc, 4d block, a true Transition Metal
44 Ruthenium, Ru	[Kr]4d75s1	[Kr]4d5s	Ru, 4d block, a true Transition Metal
45 Rhodium, Rh	[Kr]4d85s1	[Kr]4d5s	Rh, 4d block, a true Transition Metal
46 Palladium, Pd	[Kr]4d10	[Kr]4d5s	Pd, 4d block, a true Transition Metal
47 Silver, Ag	[Kr]4d105s1	[Kr]4d5s5p	Ag, 4d block, a true Transition Metal
48 Cadmium, Cd	[Kr]4d105s2	[Kr]4d5s5p	Cd, 4d block, not true Transition Metal
49 Indium, In	[Kr]4d105s25p1	[Kr]4d5s5p	In, p-block, Gp3/13,
50 Tin, Sn	[Kr]4d105s25p2	[Kr]4d5s5p	Sn, p-block, Gp4/14,
51 Antimony, Sb	[Kr]4d105s25p3	[Kr]4d5s5p	Sb, p-block, Gp5/14,
52 Tellurium, Te	[Kr]4d105s25p4	[Kr]4d5s5p	Te, p-block, Gp6/16,
53 Iodine, I	[Kr]4d105s25p5	[Kr]4d5s5p	I, p-block, Gp7/17 Halogen,
54 Xenon, Xe	[Kr]4d105s25p6 = [Xe]	[Kr]4d5s5p v. stable	Xe, p-block, Gp 0/18 Noble Gas,
55 Caesium, Cs	[Xe]6s1	[Xe]6s	Cs, s-block, Gp1 Alkali Metal,
56 Barium, Ba	[Xe]6s2	[Xe]6s	Ba, s-block, Gp2 Alkaline Earth Metal,
57 Lanthanum, La	[Xe]5d16s2	[Xe]5d6s	La, start of 5d-bock and Lanthanide Series
58 Cerium, Ce	[Xe]4f26s2 not 4f15d16s2	things get a bit less systematic in the f blocks	Ce, 1st of f-block in the Lanthanides Metals
**************************	****************************************	**********************************************************	***************************************************

 2.4 Electron configuration and the Periodic Table

Not all the elements are shown but the position of s, p, d and f blocks are shown and explained after the table

• Note on Group numbers: Using 0 to denote the Group number of Noble Gases is very historic now since compounds of xenon known exhibiting a valency of 8.

  • Because of the horizontal series of elements e.g. like the Sc to Zn block (10 elements), Groups 3 to 0 can also be numbered as Groups 13 to 18 to fit in with the actual number of vertical columns of elements.

  • This can make things confusing, but there it is, classification is still in progress!

  • The atomic/proton number, decides which element an atom is and the outer electron structure decides which group/block/series the element belongs to and ultimately its chemistry.

  • The s p d f blocks are shown in the Periodic Table above.

• The most stable electron configurations

  • When the outer s and p quantum levels (and any completely filled inner orbital quantum levels eg 3d or 4f) you get a particularly stable element with minimal chemical reactivity ie you get a Noble Gas element [simple electron notation in ()]

    • Z = 2, helium, 1s² = [He] (2)

    • Z = 10, neon, 1s²2s²2p⁶ = [Ne] (2.8)

    • Z = 18, argon, 1s²2s²2p⁶3s²3p⁶ = [Ar] (2.8.8)

    • Z = 36, krypton, [Ar]3d¹⁰4s²4p⁶ = [Kr] (2.8.18.8)

    • Z = 54, xenon, [Kr]4d¹⁰5s²5p⁶ = [Xe]

    • Z = 86, radon, [Xe]5d¹⁰6s²6p⁶ =[Rn]

• What is the electronic basis of Groups of elements? - their 'electronic classification'

  • For groups 1 to 2, and 'old' 3 to 0/'new' notation 13 to 18 (except He), all the elements in the same vertical column have the same outer electron configuration and therefore will be expected to have a very similar chemistry.

    • This gives the electronic basis for Mendeleev's brilliant conception of the periodic table, ie laying out all the elements in order of 'atomic weight' and lining them up to give vertical columns of chemically and physically similar elements.

  • For the d blocks of Groups 3 to 12, using the 'new' group number notation, the vertical 'group' connection of similar outer electron configuration is consistent except for V/Nb, Fe/Ru, Co/Rh, Ni/Pd where the 3d/4s and 4d/5s pairs of levels are of very similar energy and small differences in outer electron configuration occur.

    • Never-the-less these pairs of elements show strong similarities as part of the justification for denoting the Transition Metals plus Groups 4 to 0 as Groups 3 to 18.

• What is the electronic basis for the 'series of elements'? - their 'electronic classification'

  • The '1st Transition Metals Series' from Sc to Zn, and other 'horizontal blocks' are sometimes called a 'series' but they are better described as the '3d block' or '3d series of elements' (and, 4d block, 4f block - filling of 4f sub-shell etc.), but a horizontal row of elements, unlike the vertical columns of the eight vertical groups.

    • Why is 'block' better than 'series'?

      • The reference to the electronic structure is very important, the word series is a bit vague!

      • Technically, scandium (Sc, Z = 21) and zinc (Zn, Z = 30), are NOT true transition metals BUT they are true 3d block elements!

        • See Detailed Advanced Level Transition Metal Notes

• What is the overall electronic basis for blocks of elements across the whole of the periodic table?

  • The s-block consists of Groups 1 and 2 where the only outer electrons are in an s sub-energy level orbital (no outer p electrons, 2 per period).

  • The p-block corresponds to Groups 3 to 0 (old notation) or Groups 13 to 18 (new notation) where the three p sub-energy level orbitals are being filled (6 per period).

  • Starting with period 4, where the first of the d sub-shells is low enough in energy to be filled, there are ten elements 'inserted' between groups 2 and 3, the so-called d blocks of ten elements (the 1st block, the 3d block Sc-Zn is on Period 4).

    • Therefore Sc to Zn form the head elements of Groups 3 to 12 using the 'new' group number notation.

    • Similarly on period 5 there is a 4d block where the 4d sub-shell level is filled.

    • So 10 d block elements per period are now permitted\under the quantum number rules.

  • Starting with cerium (Z=58, period 6), see in full table below, there is a further insertion of fourteen elements where the seven f-orbital sub-shell is being filled after the first of the d-block metals and similarly with thorium (Z=90) in period 7 and these are known as the f blocks (14 per period where permitted).

• The full Periodic Table is shown below without the electron configurations, but including the new/old group number notation.

• Notes:

  1. The Noble Gases have been referred to as Group 0 because they were believed not to form compounds with other elements.

     • However, since 1961, many compounds of xenon have been prepared including xenon(VIII) oxide, XeO₄, thus attaining the expected maximum possible oxidation state, so Group 18 seems most appropriate to use these days for advanced level courses.

  2. The d block elements are sometimes referred in terms of vertical columns as Groups 3 to 12, and the subsequent p-block group columns as Groups 13 to 18.

     • Whether this will become standard at pre-university level, I don't know? but I think its a bit confusing for school level chemistry below pre-university courses like UK GCSE or US grades 6-10.

• The s p d f blocks are shown in the Periodic Table above.

 2.5 Electronic configuration of ions and oxidation states

• The electron configuration of ions:

  • Beware in quoting the configurations for simple ions where, although the order of removal is basically the reverse of the order for filling the energy levels, there is one important exception you should know.

    • p electrons are remove before the s electrons for the same principal quantum number.

    • For d/transition blocks/series the 4s electrons are 'removed' before the 3d electrons and similarly the 5s electrons are 'removed' before the 4d electrons.

  • Positive ions are formed by electron loss and the order of removal is the reverse of the order the full electron configuration is written out e.g.

    • sodium atom Na = 1s²2s²2p⁶3s¹ , sodium ion Na⁺ = 1s²2s²2p⁶ = [Ne]

    • calcium atom is Ca = 1s²2s²2p⁶3s²3p⁶4s², calcium ion Ca²⁺ = 1s²2s²2p⁶3s²3p⁶ = [Ar]

    • iron atom Fe =  [Ar]3d⁶4s², iron(II) ion Fe²⁺ = [Ar]3d⁶, iron(III) ion Fe³⁺ = [Ar]3d⁵

    • germanium atom Ge = [Ar]3d¹⁰4s²4p², germanium(II) ion Ge²⁺ = [Ar]3d¹⁰4s², germanium(IV) ion Ge⁴⁺ = [Ar]3d¹⁰

  • Negative ions are formed by electron gain and the filling order rule is continued e.g.

    • chlorine Cl = [Ne]3s²3p⁵, chloride ion Cl^- = [Ne]3s²3p⁶ = [Ar]

    • oxygen: O = [He]2s²2p⁴, oxide ion O^2- = [He]2s²2p⁶ = [Ne]

    • phosphorus: P = [Ne]3s²3p³, phosphide ion P^3- = [Ne]3s²3p³ = [Ar]

    • Note the maximum negative oxidation state is governed by the number of electrons needed to complete a noble gas structure in the covalent or ionic bonding situation.

• Oxidation state and electronic structure: For more details see also the notes on oxidation state and redox reactions.

  • The maximum oxidation state is often, but not always, limited by an inner full noble gas structure with or without a full d/f sub-shell.

  • The maximum oxidation state from Group 1 Alkali Metals (+1) to Group 0 Noble Gases (+8) is numerically equal to the number of outer electrons, i.e. those beyond an inner noble gas core or inner noble gas plus a full d/f sub-shell e.g.

    • Group 1, outer electron configuration s¹, eg sodium is +1 in sodium chloride NaCl

    • Group 2, outer electron configuration s², eg magnesium is +2 in magnesium oxide MgO

    • Group 3 (13), outer electron configuration s²p¹, eg aluminium is +3 in aluminium fluoride AlF₃

    • Group 4 (14), outer electron configuration s²p², eg silicon is +4 in silicon dioxide SiO₂

    • Group 5 (15), outer electron configuration s²p³, eg phosphorus is +5 in the phosphate(V) ion PO₄^3-

    • Group 6 (16), outer electron configuration s²p⁴, eg sulphur is +6 in sulphur trioxide SO₃

    • Group 7 (17), outer electron configuration s²p⁵, eg chlorine is +7 in the chlorate(VII) ion ClO₄^-

    • Group 0 (18), outer electron configuration s²p⁶ (except He), eg xenon is +8 in xenon tetraoxide (tetroxide), xenon(VIII) oxide XeO₄

      • The maximum oxidation state pattern for the d blocks is a bit more complicated and the trend goes through a maximum e.g.

      • maximum oxidation states for the 3d block and transition Metal Series:

      • Sc (+3), Ti (+4), V (+5), Cr (+6), Mn (+7), Fe (+3, maybe +6?), Co (+3), Ni (+3), Cu (+3), Zn (+2)

SPECTROSCOPY, the HYDROGEN SPECTRUM and IONISATION ENERGY PATTERNS are on a separate page now

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keywords-notation: 1s1 1s2 1s22s1 1s22s2 1s22s22p1 1s22s22p2 1s22s22p3 1s22s22p4 1s22s22p5 1s22s22p6 1s22s22p63s1 1s22s22p63s2 1s22s22p63s23p1 1s22s22p63s23p2 1s22s22p63s23p3 1s22s22p63s23p4 1s22s22p63s23p5 1s22s22p63s23p6 1s22s22p63s23p64s1 1s22s22p63s23p64s2 1s22s22p63s23p63d14s2 1s22s22p63s23p63d24s2 1s22s22p63s23p63d34s2 1s22s22p63s23p63d54s1 1s22s22p63s23p63d54s2 1s22s22p63s23p63d64s2 1s22s22p63s23p63d74s2 1s22s22p63s23p63d84s2 1s22s22p63s23p63d104s1 1s22s22p63s23p63d104s2 [Ar]3d104s24p1 [Ar]3d104s24p2 [Ar]3d104s24p3 [Ar]3d104s24p4 [Ar]3d104s24p5 [Ar]3d104s24p6 [Kr]5s1 [Kr]5s2 [Kr]4d15s2 [Kr]4d25s2 [Kr]4d45s1 [Kr]4d55s1 [Kr]4d55s2 [Kr]4d75s1 [Kr]4d85s1 [Kr]4d10 [Kr]4d105s1 [Kr]4d105s2 [Kr]4d105s25p1 [Kr]4d105s25p2 [Kr]4d105s25p3 [Kr]4d105s25p4 [Kr]4d105s25p5 [Kr]4d105s25p6 [Xe]6s1 [Xe]6s2 [Xe]5d16s2 [Xe]4f26s2  

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