2.8: Oxidation states of transition metals (2023)

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    The periodic table provides very useful clues as to the structure and configuration of the electrons in a given atom. Table order is handy for counting, and in most cases the easiest way to solve a problem is to take a standard case and change it. In general, neutral atoms are defined as those that have the same number of electrons and protons; Charge "discharges" and the atoms are stable. However, in bond formation, valence electrons or electrons in the outermost shells of an atom can form bonds to lower the overall energy of the system. In transition metals, the partial loss of these diffuse electrons is called oxidation. please readOxidation Reduction Reactionsif this concept is unfamiliar.


    Filling atomic orbitals requires a certain number of electrons. The s-block consists of elements from groups I and II, the alkali metals and the alkaline earth metals (sodium and calcium belong to this block). Groups XIII through XVIII include the p-block containing the nonmetals, halogens, and noble gases (carbon, nitrogen, oxygen, fluorine, and chlorine are common members). The transition metals are in the d-block between Groups III and XII. If the table below seems strange or the instructions are not clear, see the section aboutAtomorbital.

    Tabla 1:
    Orbital Orbital p d Orbital
    1 orbital, 2 electrons 3 orbits: pX, Pj, Pz; 6 electrons 5 Orbital: dX2-y2, Dz2, Dxy, Dand, Dxz; 10 electrons
    Orbital with the highest energy for a given quantum number n Degenerate with s orbitals of quantum number n+1

    The main thing to rememberelectronic configuration is that the most stable noble gas configuration is idealfor each atom. Linking is one way to approach this setup. In particular, transition metals form softer bonds with anions, cations, and neutral complexes compared to other elements. This is because the d orbital is quite diffuse (the f orbital of the lanthanide and actinide series even more so).

    Electron configuration of the neutral atom

    The periodic table makes it easy to determine which electrons are in which orbitals. As mentioned above, by counting the number of protons (atomic number) you can determine the number of electrons in a neutral atom. Sorting by blocks speeds up this process. If you are unsure about this counting system and the filling of electron orbitals, read the section aboutElectronic configuration.

    For example, if we were interested in the electronic organization ofVanadium(atomic number 23), we would start with hydrogen and work our way down (cfperiodic table).

    1s (H, He), 2s (Li, Be), 2p (B, C, N, O, F, Ne), 3s (Na, Mg), 3p (Al, Si, P, S, Cl, Ar) , 4s (K, Ca), 3d (Sc, Ti, V).

    Reference to the following periodic table confirms this organization. We have 3 elements in the 3D orbital. Therefore we write in the order in which the orbitals were filled.

    1s22s22p63 Sek23p64s23d3Ö[Ar] 4s23d3.

    The neutral atomic configurations of the fourth period transition metals are given in Table 2.

    Table 2:
    South Carolina Von v kr Minnesota Fe Pursue em copper Zink
    [Ar] 4s23d1 [Ar] 4s23d2 [Ar] 4s23d3 [Arkansas]4s23d4 [Ar] 4s23d5 [Ar] 4s23d6 [Ar] 4s23d7 [Ar] 4s23d8 [Arkansas]4s23d9 [Ar] 4s23d10
    [Ar] 4s13d5 [Ar] 4s13d10

    What may seem anomalous is the case exploiting degeneracy.

    Briefly note where the item is located.Chrom(Atomic number 24) is on the periodic table (see below). The electronic configuration of chrome is not

    ***4s2******([Ar] 4s23d4)
    ***3d4X2-y2 z2 xy and xz

    (Video) How To Calculate Oxidation Numbers - Basic Introduction

    but instead it is

    ***4s1******([Ar] 4s13d5)
    ***3d5 X2-y2 z2 xy and xz

    especially due to the degeneracy of the s and d orbitals. It is not a mistake to assume that an electron in the s orbital will shift to take the place of an electron in the d orbital because their associated energies are equal. At least theConstruction principlestates that the lowest energy configuration is the unpaired electrons in the largest possible space. According to Coulomb's law, the electrostatic force is inversely proportional to the distance; this unnecessarily paired s orbital electron can be freed from its excess energy.

    Finally for the previous twoperformance chartsTo be true in nature, the distance between the 4s and 3d orbitals would be neglected. There is a small gap for the transition metals on the right side of the block, but for purposes of the ionization discussion, the order listed is true. The higher energy orbitals are marked above the smaller ones.

    Oxidation states of transition metal ions

    When we consider ions, we add or subtract negative charges from an atom. Taking atomic orbitals into account when assigning oxidation numbers helps to see that the transition metals are a special case, but are no exception to this convenient method. An atom that gains an electron to achieve a more stable configuration is given an oxidation number of -1. The loss of an electron is then +1. When a transition metal loses electrons, it tends to lose its s orbital electrons before any of its d orbital electrons. For a more detailed discussion of the form of these compounds seeFormation of coordination complexes.

    example 1

    Write the electron configurations of:

    1. neutral iron,
    2. Iron(II) ions and
    3. pure iron(III).


    Iron's atomic number is 26, so there are 26 protons in the species.

    1. Fe: [Arkansas] 4s2 3d6
    2. Fe2+: [Arkansas] 3d6
    3. Fe3+: [Arkansas] 3d5

    Note that electrons are lost from the s orbitalFirst, then the electrons in the d orbital.

    (Video) Transition Metals Exam Question|A-Level Chemistry Past Paper Walkthrough (AQA)

    example 2

    Determine the most stable configuration between the following pair:

    1. [DKK] 5 p24d6against [Kr] 5s14d7
    2. Agriculture1+against agriculture2+


    1. This describes ruthenium. There is only one5 SekElectronic.
    2. Prata oxidada uma vez ([Kr] 4d10) is more stable than twice-([Kr] 4d9).

    Variable oxidation states

    The following table describes the most common oxidation states of period 3 elements.

    Tabla 3:
    chico # South Carolina Von v kr Minnesota Fe Pursue em copper Zink
    +1 X
    +2 X X X X X X X X X
    +3 X X X X X X X X X X
    +4 X X X X X
    +5 X X X
    +6 X X X
    +7 X

    This diagram contains some concepts that illustrate the stable states for specific elements.

    Example 3

    What Makes Zinc Stable as Zn?2+? What makes scandium stable as Sc?3+?


    (Video) Transition metals as catalysts

    Zinc has the neutral configuration [Ar]4s23d10. Losing 2 electrons does not change the entire d orbital. Neutral scandium is written as [Ar]4s23d1. The loss of 3 electrons brings the configuration to the main state with valency 3p6.

    example 4

    Why iron is almost always Fe2+you managed3+?


    Iron is written as [Ar]4s23d6. Lose 2 electrons from the s orbital (3d6) o 2 s- e 1 d-Orbital (3d5) electron are reasonably stable oxidation states.

    Example 5

    Write manganese oxides in a few different oxidation states. What is possible and/or useful?


    although Mn+2is the most stable ion for manganese, the d orbital can be tricked into removing 0 to 7 electrons. Therefore, manganese compounds range from Mn(0) to Mn(S), Mn(II) as MnO, Mn(II,III) as Mn3Ö4, Mn(IV) als MnO2, or manganese dioxide, Mn(VII) in the permanganate ion MnO4-, etc.

    Effect of oxidation state on physical properties

    The transition metals have high boiling points. d orbitals allow electrons to diffuse and berelocatedinside the solid metal. This increases the attractive forces between atoms and requires more energy to dissociate them and change phase. This attraction reaches a maximum in Group IV for manganese (boiling point 2061°C), which has 5 unpaired electrons. Manganese's potential to form strong and numerous bonds is greater than that of its neighbors. Zinc has a low boiling point (907°C) for the same reason: it doesn't have much attraction between like atoms. Also on the 12thºMercury has a low melting point (-39°C), which makes it a liquid under normal conditions.

    ÖLanthanoid Contractionis a term that describes two different periodic trends. The first is that the Group VI transition metals are separated by 15 additional elements, moving towards the bottom of the table. The lanthanides introduce f orbitals that are very diffuse and do not shield well. Because the extra protons are now more visible to these electrons, the atomic radius of a Group VI transition metal shrinks to the point where the atomic radii are approximately equal to those of Group V transition metals. The second definition explains the general decrease in ionic and atomic radii upon viewing of the transition metals from left to right. This is due to the addition of electrons to the same diffuse f orbital when protons are added. This leads to a greater attraction between protons and neutrons. The term refers to the same idea that f-orbitals do not shield electrons efficiently, but refers to comparisons between elements horizontally and vertically.

    (Video) 2.8 Nomenclature Part 1

    Manganese: a case study

    Manganese is widely studied as an important reducing agent in chemical analysis. It is also being studied in biochemistry for catalysis as well as in alloying enrichment. Manganese is required in small amounts in plants; higher doses begin to react with enzymes and inhibit some cellular functions. Because of manganese's flexibility to adopt many oxidation states, it is a good example to describe general trends and concepts behind electron configurations.

    The electron configurations of unpaired electrons are said to beparamagneticand react to the proximity of magnets. Fully paired electrons arediamagneticand do not feel this influence. Manganese in particular has both paramagnetic and diamagnetic orientations depending on its oxidation state.

    Minnesota2Ö3is manganese(III) oxide with manganese in the +3 state. 4 unpaired electrons means this complex isparamagnetic.

    3d4 X2-y2 z2 xy and xz

    MnO2is manganese(IV) oxide with the manganese in the +4 state. 3 unpaired electrons means this complex isless paramagneticmake mn3+.

    3d3 X2-y2 z2 xy and xz

    KMnO4is potassium permanganate with the manganese in the +7 state. There are no electrons in the 4s and 3d orbitals. 3p orbitals have no unpaired electrons, so this is complexdiamagnetic.

    3d0 X2-y2 z2 xy and xz


    The oxidation states of transition metals follow the general rules for most other ions, except that the d orbital degenerates to the higher quantum number s orbital. Transition metals achieve stability by rearranging and oxidizing their electrons or donating electrons to other atoms and ions. These resulting cations participate in theFormation of coordination complexesor synthesis of other compounds.


    1. Oxtoby D, Gillis HP, Campion, A.Basics of modern chemistry, 6ºeditionThomson Brooks/Cole, Belmont. 2008; 313-318.
    2. Audi A, Sherwood, P.Valence band X-ray photoelectron spectroscopic studies of manganese and its oxides interpreted by group and band structure calculations; search. interface analysis; 2002; 33; 274-282.
    3. Reaney S., Kwik-Uribe C., Smith D.Oxidation state of manganese and its effect on toxicity.Chemical Res. Toxicol.; 2002; fifteen; 1119-1126.
    4. Manual CDN, 88ºSkt Issue 1, Pr. 1 Electron Configuration and Ionization Energy of Neutral Atoms in the Ground State; 13-14.
    5. Manual CDN, 88ºSkt Edition 4, Pr. 1 Melting, boiling, triple and limit point temperatures of the elements; 133-134.
    (Video) How to Find the Number of Valence Electrons for Transition Metals


    • Margaux Kreitmann (UCD)


    What are the oxidation states of transition metal? ›

    Oxidation State of Transition Elements
    ElementOuter Electronic ConfigurationOxidation States
    Fe3d64s2+2, +3, +4, +5, +6
    Co3d74s2+2, +3, +4
    Ni3d84s2+2, +3., +4
    Cu3d104s1+1, +2
    6 more rows

    Why is the +2 oxidation state so common for transition metals? ›

    Answer and Explanation: As transition metal exhibits s, p, d, and f subshell. These orbitals have a very large volume and they exhibit less tendency to donate electrons. Therefore, the most transition metals lose two electrons present in an orbital and attain a +2-oxidation state.

    Which transition metal shows 3 oxidation states? ›

    Gd shows only +3 oxidation state.

    Which element has oxidation states of +2 and +3? ›

    The (II) and (III) are the oxidation states of the iron in the two compounds: +2 and +3 respectively. That tells you that they contain Fe2+ and Fe3+ ions.

    Why iron is stable at 3 oxidation state than 2? ›

    So iron is more stable in +3 oxidation state due to the fact that of half filled electronic configuration and Manganese is more stable in +2 oxidation state. Therefore, from the above fact we see that Manganese is more stable in + 2 oxidation state than in + 3 and Iron is more stable in + 3 than in + 2. Note: 1.

    Why +2 oxidation state is more stable? ›

    Due to the inert pair effect lead (Pb) has the most stable oxidation state. As we move down the group, the stability of lower oxidation state increases. Hence in Pb group, as we move down the stability of +2 state goes on becoming more than +4 state due to inert pair effect. Q.

    What is the highest oxidation state of transition metals? ›

    A transition metal exhibits highest oxidation state in oxides and fluorides.

    What transition metal has a 3+ charge? ›

    Transition Metal Ions
    Table 7.5.1: Common Transition Metal Ions
    copper (I), Cu+cadmium, Cd2+chromium (III), Cr3+
    gold (I), Au+chromium (II), Cr2+cobalt (III), Co3+
    mercury (I), Hg2+2cobalt (II), Co2+gold (III), Au3+
    9 more rows
    Sep 20, 2022

    Which has only +3 oxidation state? ›

    Scandium (Sc) just displays a +3-oxidation state in these series.

    Which of the following is only 3 oxidation states? ›

    Thus, we can say that Ac is only compound which shows only +3 oxidation state.

    Is 2+ to 3+ oxidation or reduction? ›

    In this example, Fe2+ is oxidized and Ce4+ is reduced. The charge of Fe went from +2 to +3, that is, it lost an electron. This process is called oxidation. Oxidation: The loss of an electron by a substance.

    Which of the following lanthanide +2 and +3 oxidation states are most common? ›

    But the most stable oxidation state of Lanthanides is +3.

    How do you determine oxidation states? ›

    The oxidation number of each atom can be calculated by subtracting the sum of lone pairs and electrons it gains from bonds from the number of valence electrons. Bonds between atoms of the same element (homonuclear bonds) are always divided equally.

    Why manganese is more stable in +2 state than +3 state? ›

    It is known that half-filled and fully-filled orbitals are more stable. Therefore, Mn in (+2) state has a stable d5 configuration. This is the reason Mn2+ shows resistance to oxidation to Mn3+.

    Which is more stable Fe2+ or Fe3+ and why? ›

    Fe3+ ion is more stable than Fe2+ ion. This is explained on the basis of the electronic configuration of the two ions Fe3+ on whit all the five 3d orbitals half filled, is more symmetrical than Fe2+ on in which four 3d orbitals are half filled and one is filled. Therefore, Fe3+ on is more stable than Fe2+ ion.

    Why is +3 oxidation state the most stable? ›

    - It means that one electron is present in each orbital due to which it is more stable than the d5 configuration. - That's why the oxidation state of +3 is the most stable oxidation state than the +4, +2 and +6 oxidation states.

    How does the stability +2oxidation state compare? ›

    The relative stability of the +2 oxidation state increases on moving from top to bottom. This is because on moving from top to bottom, it becomes more and more difficult to remove the third electron from the d-orbital.

    Which metal has most stable +2 oxidation state? ›

    Pb has most stable +2 oxidation state due to inert pair effect.

    Why does 2 oxidation state decrease down the group? ›

    On moving down the group, the size of the atom increases and the electronegativity decreases. Thus, the tendency to accept two more electrons as to attain octet in outermost shell decreases, i.e. the tendency to show −2 oxidation state decreases.

    Which transition elements show highest oxidation state of 8? ›

    Reason: Osmium is a 5d-block element.

    How do you know which oxidation state is the highest? ›

    The highest oxidation state of an element is determined using the periodic table by the group in which it is located. Metals in all compounds have a positive oxidation state. In compounds with non-metals, hydrogen has an oxidation state of +1, and an oxidation state of -1 with metals.

    What is the most stable oxidation state of TL? ›

    Thallium exhibits stable oxidation state + 1, than + 3 due to inert pair effect.

    What transition metals have a 2+ charge? ›

    Many of the transition metals (orange) can have more than one charge. The notable exceptions are zinc (always +2), silver (always +1) and cadmium (always +2).

    Do transition metals have a +2 charge? ›

    Because most transition metals have two valence electrons, the charge of 2+ is a very common one for their ions.

    Are transition metals group 2 or 3? ›

    The transition elements or transition metals occupy the short columns in the center of the periodic table, between Group 2A and Group 3A.

    What are the 4 oxidation states? ›

    Cerium is well known to exhibit +4 oxidation state because after loosing 4 electrons it attains stable noble gas configuration. Q.

    Which has the most stable +3 oxidation state? ›

    Al is the most stable element in +3 oxidation state.

    Why does +3 oxidation state becomes less? ›

    Solution : The stability of +3 oxidation state of group 13 elements decreases down the group due to the inert pair effect on ns2 electrons. This is because of the poor shielding effect of electron in d and f orbitals.

    What does an oxidation state of +3 mean? ›

    The iron ion Fe3+, for example, has an oxidation number of +3 because it can acquire three electrons to form a chemical bond, while the oxygen ion O2 has an oxidation number of −2 because it can donate two electrons.

    Which of the ion is stable in 3 oxidation state? ›

    The +3 oxidation state of lanthanum (Z=57), gadolinium (Z=64) and lutetium (Z=71) are especially stable.

    Can carbon have a +3 oxidation state? ›

    Elements can usually have a wide range oxidation states. However certain states are more common than others. Carbon has been observed to have oxidation states of 0, ±1, ±2, ±3, and ±4.

    What does a +2 oxidation state mean? ›

    If the oxidation number is positive, the atom loses electrons; if the oxidation number is negative, the atom acquires electrons. Calcium has a charge of +2, indicating that it has lost two electrons. The -2 charge of oxygen indicates that it has gained two electrons.

    What does +2 oxidation number mean? ›

    Calcium has a +2 charge, which means it lost two electrons. Oxygen has a -2 charge, which means it gained two electrons. If an atom loses electrons, its oxidation number is positive, so we can say that this atom undergoes oxidation.

    Why is +3 oxidation state highly oxidising? ›

    whereas the +3 oxidation state is highly oxidising in character. The compounds in +1 oxidation state, as expected from energy considerations, are more ionic than those in +3 oxidation state. In trivalent state, the number of electrons.

    What is the most common oxidation state of lanthanides +2 +4 +3 +6? ›

    +3 is the most common oxidation state shown by lanthanides and actinides.

    In which lanthanoid +2 oxidation state is most stable? ›

    Electronic configuration of Europium is 4f76s2. Hence the +2 state is most stable for Eu. As this leads to a half filled electronic shell, this state would be stable.

    Why +3 is most common oxidation state of Lanthanoids? ›

    Ans. Lanthanides have a stable and common oxidation state of +3. The outermost two electrons of 6s electrons and one electron from 4f electrons are removed to achieve this. It is tough to remove additional electrons from the 4f subshell due to the significant energy difference between 4f and 6s.

    What does a higher oxidation state mean? ›

    The value of the highest oxidation state is always positive. The more the positive value of the oxidation state, it means the elements have had more electrons removed for forming a stable form. Losing electrons is indicated by the positive value of the oxidation state.

    What is an example of oxidation states? ›

    For example oxidation state of elemental atoms such as sodium, magnesium, iron is zero. Similarly, the net oxidation state of neutral molecules such as oxygen, chlorine, water, ammonia, methane, potassium permanganate is zero. The oxidation state of atoms in homo-polar molecules is zero.

    Which transition metal has the most oxidation states? ›

    (i) Mn shows the highest oxidation state of +7 with oxygen but with fluorine it shows the highest oxidation state of +4. (ii) Zirconium and Hafnium exhibit similar properties.

    How do you find the oxidation state of a transition metal complex? ›

    To determine the oxidation state of the metal, we set the overall charge equal to the sum of the ligands and the metal: +1 = −2 + x, so the oxidation state (x) is equal to 3+.

    How do you determine the highest oxidation state of a transition metal? ›

    The formula for determining oxidation states would be (with the exception of copper and chromium): Highest Oxidation State for a Transition metal = Number of Unpaired d-electrons + Two s-orbital electrons.

    Which is the strongest oxidation state? ›

    Fluorine is the strongest oxidizing agent because it is the strongest oxidant among all the elements. When it reacts with gold and ice then it shows strong oxidizing properties even at - 100 ° C .

    What is the highest oxidation state? ›

    The highest known oxidation state is +9 in the tetroxoiridium (IX).

    Which transition element shows 7 oxidation states? ›

    Mn atom in the permanganate ion shows +7 oxidation state. The oxygen in it shows -2 oxidation state.

    How do transition elements show oxidation states? ›

    They show variable oxidation state because transition metals have (n-1)d orbitals empty that are closer to the outermost ns orbital in energy levels. These orbitals are never fully filled. So, they can always accommodate more electrons in (n-1)d orbitals.

    How do you find the highest and lowest oxidation state? ›

    General rules of the oxidation state of an element

    However, a decrease in the oxidation state of an atom is known as reduction. Hence, the elements that gain electrons have the lowest oxidation state. The elements which lose electrons are known to have the highest oxidation state.


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