Anonymous asked in 科學化學 · 1 decade ago

兩問題共40點~ 無機化學 翻譯與解釋名詞問題?



2.inductive effects

3.steric effects

4.strength of oxyacide

5.what is superacide(定義&為什麼會存在)

6.立體障礙 absorption law

8.term symbol

9.spin-orbit coupling

10.selection rules for absorption spectra

11.tanable-sugano diagrams

12.charge transfer spectra

再開另一題目 也是關於無機化學 也是20點

Update 2:

打錯了 是oxyacid




Update 3:




1 Answer

  • sky
    Lv 4
    1 decade ago
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    An adduct is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all components The resultant is considered a distinct molecular species.Adducts often form between Lewis acids and Lewis bases.A good example would be the formation of adducts between the Lewis acid borane and the oxygen atom in the Lewis bases, tetrahydrofuran (THF) or diethyl ether: BH3•THF, BH3•OEt2.


    請參考: 1.Miessler and Tarr , inorganic chemistry , 3 ed ,P192


    2.inductive effect :the electron donating or withdrawing effect that is transmitted through σ-bonds.The electron cloud in a σ-bond between two unlike atoms is not uniform and is slightly displaced towards the more electronegative of the two atoms.

    If the electronegative atom is then joined to a chain of atoms, usually carbon, the positive charge is relayed to the other atoms in the chain. This is the electron-withdrawing inductive effect, also known as the -I effect.例如鹼性強度:PH3>PF3, 後者P上的孤對電子的電子密度因F原子的強電負度而降低,造成鹼性下降

    Some groups, such as the alkyl group are less electron-withdrawing than hydrogen and are therefore considered as electron-releasing. This is electron releasing character is indicated by the +I effect.例如鹼性強度:NMe3>NHMe2>NH2Me>NH3, alkyl group具有推電子能力,越多造成N上電子密度越強越鹼

    請參考: 1.Miessler and Tarr , inorganic chemistry , 3 ed ,P196


    2009-04-21 09:58:06 補充:

    3. steric effects: If atoms are brought too close together, there is an associated cost in energy due to overlapping electron clouds

    無機化學的常見例子為F(front) strain 及 Back (B) strain

    請參考: 1.Miessler and Tarr , inorganic chemistry , 3 ed ,P199-200


    2009-04-21 10:07:21 補充:

    建議多翻幾本書吧,您問的問題教材都有, 可以先翻課本後面的index來找較快,課本不外乎1.Miessler and Tarr , inorganic chemistry

    2.Atkins, inorganic chemistry

    3.Huheey, inorganic chemistry

    4.Douglas, inorganic chemistry


    2009-04-25 08:14:38 補充:

    F(front) strain: the bulky groups interfere directly with the approach of an acid and a base to each other. ex: Et3N+Me3N

    路以士酸及鹼各自的alkyl group之間產生的立體阻礙防止二者形成adduct

    2009-04-25 08:14:54 補充:

    Back (B) strain: the bulky groups interfere each other when VSEPR effects force them to bend away from the other molecule forming the adduct.

    ex:Me3N+BF3/BMe3/B(t-Bu)3即當adduct形成後,N上的alkyl group之間產生的立體crowding

    2009-04-25 08:40:38 補充:


    The larger the number of nonhydrogenated oxygens, the stronger the acids because nonhydrogenated oxygens is highly electronegative (-I effect) ,after deprotonization, and the larger the number of these oxygens to share the hegative charge

    2009-04-25 08:41:23 補充:

    the more stable and weaker the conjugate base and the stronger the hydrogenated acid.ex:HClO4>HClO3>HClO2>HClO


    or Pka=8-5n , n:nonhydrogenated oxygen atoms

    2009-04-25 18:56:17 補充:

    請參考: 1.Miessler and Tarr , inorganic chemistry , 3 ed ,P196-197

    2009-04-25 19:11:42 補充:

    5.A superacid is an acid with an acidity greater than that of 100% sulfuric acid, which has a Hammett acidity function (H0) of −12. Commercially available superacids include trifluoromethanesulfonic acid (CF3SO3H), also known as triflic acid, and fluorosulfuric acid (FSO3H)

    2009-04-25 19:12:25 補充:

    both of which are about a thousand times stronger (i.e. have more negative H0 values) than sulfuric acid. The strongest superacids are prepared by the combination of two components, a strong Lewis acid and a strong Brønsted acid.

    2009-04-25 19:25:47 補充:


    Steric hindrance or steric resistance occurs when the size of groups within a molecule prevents chemical reactions that are observed in related smaller molecules. Although steric hindrance is sometimes a problem, it can also be a very useful tool,

    2009-04-25 19:26:06 補充:

    and is often exploited by chemists to change the reactivity pattern of a molecule by stopping unwanted side-reactions (steric protection). Steric hindrance between adjacent groups can also restrict torsional bond angles.

    簡單講Steric hindrance立體(障礙)效應為steric effects的一種

    2009-04-25 19:53:18 補充:

    7.The Beer-Lambert law (or Beer's law) is the linear relationship between absorbance and concentration of an absorbing species. When working in concentration units of molarity, the Beer-Lambert law is written as:

    A = epsilon * b * c

    2009-04-25 19:57:33 補充:

    where epsilon is the wavelength-dependent molar absorptivity coefficient with units of L M -1 cm -1,where A is the measured absorbance(with no units a dimensionless quantity ), b is the path length(with units of cm ), and c is the analyte concentration(with units of mol L-1 ).

    2009-04-25 19:59:50 補充:

    ex: A=1, 90% absorption, 10% transmittance

    A=2, 99% absorption, 1% transmittance

    2009-04-25 20:20:07 補充:

    8.term symbol有描述多電子原子其角動量子數的Term symbol及分子光譜的Molecular term symbol

    term symbol:In quantum mechanics, the term symbol is an abbreviated description of the angular momentum quantum numbers in a multi-electron atom. It is related with the energy level of a given electron configuration.

    2009-04-25 20:21:25 補充:

    Molecular term symbol:In molecular physics, the molecular term symbol is a shorthand expression of the group representation and angular momenta that characterize the state of a molecule

    2009-04-25 21:03:30 補充:

    9.spin-orbit coupling自旋-軌域偶合:

    由於電子在軌域上的運動造成電子自旋磁偶矩的交互作用。spin-orbital coupling 的一個結果是混合了不同多樣性的 zero-order state。將造成fine structure,稱為 spin-orbit coupling,in the discussion of multielectron atoms, the spin and orbital angular momenta have been treated separately.

    2009-04-25 21:06:31 補充:

    the spin and orbital angular momenta couple with each other, known as spin-orbit coupling.In multielectron atoms, the S and L quantum numbers combine into the total angular momentum quantum number J. The quantum number J may have the following values

    J = L + S , L + S - l , L + S - 2 ,..., I L - S I

    2009-04-25 21:27:25 補充:

    10.selection rules for absorption spectra:The relative intensities of absorption bands are governed by a series of selection rules.On the basis of the symmetry and spin multiplicity of ground and excited electronicstates, two of these rules may be stated :

    2009-04-25 21:34:23 補充:

    transition between states of the different parity(Laporte selection rule) and same spin multiplicities are allowed(Spin selection rule)

    g-g transition are forbidden ex:d-d are forbidden

    g-u ransition are allowed ex:d-p are forbidden

    4A2→4T1 are spin allowed

    4A2→2T2 are spin forbidden

    2009-04-26 10:43:47 補充:

    11.Tanabe-Sugano diagrams are used to predict absorptions in the UV and visible electromagnetic spectrum of coordination compounds.A Tanabe-Sugano diagram is a graph which plots the energy of different spectroscopic terms (on the y-axis) against the size of the ligand field (on the x-axis).

    2009-04-26 10:45:08 補充:

    The units used for each are given in terms of the Racah parameter B (E/B for the y axis and Δ/B for the x-axis, where Δ is the ligand field splitting energy).This choice of unit means that the diagram takes account of electron-electron repulsion effects, which an Orgel diagram cannot.

    2009-04-26 10:49:14 補充:

    It is used to predict the energy of any absorption bands predicted but not observed in the UV/visible spectra of transition metal complexes from the energies of those that can be seen, and can also be used to predict the size of the ligand field to cause high-spin to low-spin transitions.

    2009-04-26 10:59:33 補充:




    4. Miessler and Tarr , inorganic chemistry , 3 ed ,P393-398

    2009-04-26 12:02:58 補充:

    12.charge transfer spectra

    A charge-transfer complex (or CT complex, electron-donor-acceptor-complex) is a chemical association of two or more molecules, or of different parts of one very large molecule, in which the attraction between the molecules (or parts) is created

    2009-04-26 12:04:56 補充:

    by an electronic transition into an excited electronic state, such that a fraction of electronic charge is transferred between the molecules.The resulting electrostatic attraction provides a stabilizing force for the molecular complex.

    2009-04-26 12:05:24 補充:

    The nature of the attraction in a charge-transfer complex is not a stable chemical bond and is much weaker than covalent forces, rather it is better characterized as a weak electron resonance.

    2009-04-26 12:05:59 補充:

    As a result, the excitation energy of this resonance occurs very frequently in the visible region of the electro-magnetic spectrum. This produces the usually intense colors characteristic for these complexes. These optical absorption bands are often referred to as charge-transfer bands, or CT bands.

    2009-04-26 12:10:44 補充:

    CT absorptions bands are highly intense and lie in the UV or visible portion of spectrum. The molar absorptivities, ε, of CT complexes are about 50000L mol-1 cm-1, that are three orders of magnitude higher than typical ε of 20 or lower, for d-d transitions (transition from t2g to eg).

    2009-04-26 12:12:23 補充:

    This is because the CT transitions are not spin or Laporte forbidden as d-d transitions.

    The charge-transfer bands in transition metal complexes result from movement of electrons between molecular orbitals (MO) predominantly metal in character and those that are predominantly ligand in character.

    2009-04-26 12:13:33 補充:

    If the electron moves from the MO with ligand like character to the metal like one, the complex is called ligand-to-metal charge-transfer (LMCT) complex.

    2009-04-26 12:13:54 補充:

    If the electron moves from the MO with metal like character to the ligand-like one, the complex is called a metal-to-ligand charge-transfer (MLCT) complex.Thus, a MLCT results in oxidation of the metal center whereas a LMCT results in the reduction of the metal center.

    2009-04-26 12:24:49 補充:

    CTTM(charge transfer to metal)

    LMCT(ligand to metal charge transfer)造成中心金屬的還原: ligand 為σ donor

    ex:MnO4-,CrO4-,IrBr6 2-,IrBr6 3-

    CTTL(charge transfer to ligand)

    MLCT(metal to ligand charge transfer)造成中心金屬的氧化: ligand 為 π acceptor(empty π* orbitals) such as CO,CN-,SCN-,S2CNR2-

    Source(s): , 請參考: 1.Miessler and Tarr , inorganic chemistry , 3 ed ,P203-204 2.,,, 1. 2. 3.Miessler and Tarr , inorganic chemistry , 3 ed ,P381, 1.3Miessler and Tarr , inorganic chemistry , 3 ed ,P382-389 2.term symbol請參考: 3.Molecular term symbol 請參考: 1.Miessler and Tarr , inorganic chemistry , 3 ed ,P387-388 2. 請參考: 1.Miessler and Tarr , inorganic chemistry , 3 ed ,P390, 1.Miessler and Tarr , inorganic chemistry , 3 ed ,P407-408 2.
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