# cr electron configuration

Via inhalation and dermal path, Chromium is extremely toxic and causes lung cancer, nasal inflammation, nasal ulcer, and hypersensitivity reactions such as contact dermatitis and asthma. The hexavalent form is poisonous. Cr ( Z = atomic number = 24 ) : 24 protons and 24 electrons in the neutral ground state atom. What is the difference between Atom and Molecule? The discovery that steel could be made highly resistant to corrosion and discolouration by adding metallic chromium to form stainless steel was a major development in steel production. Cr: [Ar]4s^(1)3d^5 This is an anomalous configuration, something silly that you shouldn't be tested on, in my opinion. I thought that in general, we move the s electrons to the d when we want to make the d shell half or completely filled. Electron configurations of atoms follow a standard notation in which all electron-containing atomic subshells (with the number of electrons they hold written in superscript) are placed in a sequence. To arrive at the electron configurations of atoms, you must know the order in which the different sublevels are filled. The electron configuration of chromium is [Ar]3d. The symbol Ar in the electron configuration stands for argon, which has a stable electron configuration. The electron configuration of atoms explains the common form of the periodic system of elements (Fig. 1 Answer +1 vote . How to Determine Electron Configuration . This means part of the electron configuration has been replaced with the element symbol of the noble gas symbol. A sublevel is filled or … Which electron configuration could represent a strontium atom in an excited state? There is no Cr^4+ ion in aqueous solution. Your email address will not be published. Electron Configuration Chart for All Elements in the Periodic Table. Orbital diagrams are ways to assign electrons in an atom or ion. Electrons enter available sublevels in order of their increasing energy. See for example this question to catch a small glimpse of the truth behind the simplifications.. Chromium is a chemical element with the symbol Cr and atomic number 24. This layer has a spinal structure, with just a few dense atomic layers. The Electronic configuration of chromium is [Ar]3d5 4s1. 1 decade ago. The atomic number of Cr is 24. The metal is commonly used as a catalyst as well. Neutral chromium. What is the difference between Daltons Atomic Theory and the Modern Atomic Theory? 0 0. Chromium is a chemical element with atomic number 24 and represented by the symbol Cr in the Periodic Table. It has a high melting point. Chromium burns when heated and the compound that it forms is a green chromic oxide. Sodium chromate, potassium chromate, potassium dichromate, ammonium dichromate and chromium trioxide are hexavalent chromium compounds that are widely produced. It is very thick and prevents oxygen diffusion through the metal underlying it. Chromium is a lustrous, hard metal that has a silver-grey colour. Best answer. Half-filled and fully filled subshell have got extra stability. When we write the configuration we'll put all 24 electrons in orbitals around the nucleus of the Chromium atom. With a powerful reducing agent that removes the protective oxide layer on the metal, passivation can be removed. It has a high melting point. The correct electron configuration for Cr 2+ is said to be [Ar]3d 4. Expected Electronic configuration. electron configuration of Cr3 ? What could be true if a series circuit has unequal resistances throughout the circuit? It is unstable and undergoes disproportionation. Nevertheless, check the complete configuration and other interesting facts about Bromine that most people don't know. Cr Electron Configuration. 5 years ago. What is the difference between Adenine and Guanine? The health risks associated with chromium exposure are based on its state of oxidation. It is the 22nd most abundant element in Earth's crust with an average concentration of 100ppm. Actual electronic configration. 1s2, 2s2 2p6, 3s2 3p6 3d2. the electron configuration for that of the chromium atom is: 1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 3d^5 or [ Ar ] 4s^1 3d^5. answered Jan 12, 2019 by alam905 (91.0k points) selected Jan 12, 2019 by faiz . This treated chromium metal readily dissolves in weak acids. Produced commercially by heating its ore in the presence of silicon or aluminium. The electron configuration then is: 1s2 2s2 2p6 3s2 3p6 3d6 What is chromium iii ion noble gas configuration? Please only answer if you know, and explain why. Atomic Symbol Cr Uses Used to make stainless steel. This answer may be expanded with a little more research about the configuration for chromium, but this answer will serve as just a basic information for all other necessary information about chromium. 3,090 results chemistry final-urgent electron configuration of Cr3+? Chromium with a charge of +4 has lost four electrons which come from the 4s and the 3d. Electron configurations of elements beyond hassium (element 108), including those of the undiscovered elements beyond oganesson (element 118), are predicted. Cu =1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 1 . What will be the wavelength of the photon emitted when a hydrogen atom undergoes a transition from n=5 to... What is the electron configuration for chromium? Ferrochromium alloy is commercially produced by silicothermic or aluminothermic reactions from chromite and chromium metal by processes of roasting and leaching followed by carbon and then aluminium reduction. It is steely grey and metal. What is the difference between Nintendo Wii and Microsoft Xbox 360? Therefore, one of the 4s2 electrons jumps to the 3d9. 2.3).Elements are classified into “blocks” according to the subshell that is being “filled” as the atomic number increases. However, because of either the orbital stability or the stability of having two full orbitals instead of having one full and another almost half full, we find the correct configuration to be letter B. Now, Letter A or 1s2 2s2 2p6 3s2 3p6 4s2 3d4 is the expected electronic configuration of a chromium since it has 24 electrons. because its a 6+ ion, it has lost 6 electrons. CBSE Previous Year Question Papers Class 10, CBSE Previous Year Question Papers Class 12, NCERT Solutions Class 11 Business Studies, NCERT Solutions Class 12 Business Studies, NCERT Solutions Class 12 Accountancy Part 1, NCERT Solutions Class 12 Accountancy Part 2, NCERT Solutions For Class 6 Social Science, NCERT Solutions for Class 7 Social Science, NCERT Solutions for Class 8 Social Science, NCERT Solutions For Class 9 Social Science, NCERT Solutions For Class 9 Maths Chapter 1, NCERT Solutions For Class 9 Maths Chapter 2, NCERT Solutions For Class 9 Maths Chapter 3, NCERT Solutions For Class 9 Maths Chapter 4, NCERT Solutions For Class 9 Maths Chapter 5, NCERT Solutions For Class 9 Maths Chapter 6, NCERT Solutions For Class 9 Maths Chapter 7, NCERT Solutions For Class 9 Maths Chapter 8, NCERT Solutions For Class 9 Maths Chapter 9, NCERT Solutions For Class 9 Maths Chapter 10, NCERT Solutions For Class 9 Maths Chapter 11, NCERT Solutions For Class 9 Maths Chapter 12, NCERT Solutions For Class 9 Maths Chapter 13, NCERT Solutions For Class 9 Maths Chapter 14, NCERT Solutions For Class 9 Maths Chapter 15, NCERT Solutions for Class 9 Science Chapter 1, NCERT Solutions for Class 9 Science Chapter 2, NCERT Solutions for Class 9 Science Chapter 3, NCERT Solutions for Class 9 Science Chapter 4, NCERT Solutions for Class 9 Science Chapter 5, NCERT Solutions for Class 9 Science Chapter 6, NCERT Solutions for Class 9 Science Chapter 7, NCERT Solutions for Class 9 Science Chapter 8, NCERT Solutions for Class 9 Science Chapter 9, NCERT Solutions for Class 9 Science Chapter 10, NCERT Solutions for Class 9 Science Chapter 12, NCERT Solutions for Class 9 Science Chapter 11, NCERT Solutions for Class 9 Science Chapter 13, NCERT Solutions for Class 9 Science Chapter 14, NCERT Solutions for Class 9 Science Chapter 15, NCERT Solutions for Class 10 Social Science, NCERT Solutions for Class 10 Maths Chapter 1, NCERT Solutions for Class 10 Maths Chapter 2, NCERT Solutions for Class 10 Maths Chapter 3, NCERT Solutions for Class 10 Maths Chapter 4, NCERT Solutions for Class 10 Maths Chapter 5, NCERT Solutions for Class 10 Maths Chapter 6, NCERT Solutions for Class 10 Maths Chapter 7, NCERT Solutions for Class 10 Maths Chapter 8, NCERT Solutions for Class 10 Maths Chapter 9, NCERT Solutions for Class 10 Maths Chapter 10, NCERT Solutions for Class 10 Maths Chapter 11, NCERT Solutions for Class 10 Maths Chapter 12, NCERT Solutions for Class 10 Maths Chapter 13, NCERT Solutions for Class 10 Maths Chapter 14, NCERT Solutions for Class 10 Maths Chapter 15, NCERT Solutions for Class 10 Science Chapter 1, NCERT Solutions for Class 10 Science Chapter 2, NCERT Solutions for Class 10 Science Chapter 3, NCERT Solutions for Class 10 Science Chapter 4, NCERT Solutions for Class 10 Science Chapter 5, NCERT Solutions for Class 10 Science Chapter 6, NCERT Solutions for Class 10 Science Chapter 7, NCERT Solutions for Class 10 Science Chapter 8, NCERT Solutions for Class 10 Science Chapter 9, NCERT Solutions for Class 10 Science Chapter 10, NCERT Solutions for Class 10 Science Chapter 11, NCERT Solutions for Class 10 Science Chapter 12, NCERT Solutions for Class 10 Science Chapter 13, NCERT Solutions for Class 10 Science Chapter 14, NCERT Solutions for Class 10 Science Chapter 15, NCERT Solutions for Class 10 Science Chapter 16, Important Questions For Class 11 Chemistry, Important Questions For Class 12 Chemistry, CBSE Previous Year Question Papers Class 10 Science, CBSE Previous Year Question Papers Class 12 Physics, CBSE Previous Year Question Papers Class 12 Chemistry, CBSE Previous Year Question Papers Class 12 Biology, ICSE Previous Year Question Papers Class 10 Physics, ICSE Previous Year Question Papers Class 10 Chemistry, ICSE Previous Year Question Papers Class 10 Maths, ISC Previous Year Question Papers Class 12 Physics, ISC Previous Year Question Papers Class 12 Chemistry, ISC Previous Year Question Papers Class 12 Biology, ChemSpider is a free chemical structure database, Chromium is a chemical element with atomic number 24 and represented by the symbol. Source(s): https://shorte.im/a8RU1. What is the approximate power consumed by a 10 kW heat strip rated 230V, when connected to a 208V circuit? The electron configuration for Cr is [Ar]4s1 3d5 Therefore Cr+ would be formed by removing the electron in the 4s shell making the electron configuration of Cr+ [Ar] 3d10 however after a search online someone said it is [Ar]4s1 3d4 which is correct and why? What is the difference between Kenmore Elite and Non-elite? To write the electron configuration of the following atoms and ions. therefore it will have the same electronic configuration as Ar (argon) - Ar is 6 before Cr on the periodic table. About eighty per cent of chromium that is produced annually goes towards the production of metal alloy. Now, Letter A or 1s2 2s2 2p6 3s2 3p6 4s2 3d4 is the expected electronic … Your email address will not be published. Chromium compounds are prized for their bright colours of green, purple, red and orange as pigments. Chromium protects the metal below by immediately producing a thin oxide layer that is impermeable to. A brief interaction with oxidising acids such as nitric acid can improve passivation. The electron configuration of chromium is [Ar]3d 5 4s 1, which can be explained by the stability offered by a half-filled d-orbital. 0. reply. 0 0. shalleep. Source(s): electron configuration cr 3: https://shortly.im/igmCb. In order to write the Chromium electron configuration we first need to know the number of electrons for the Cr atom (there are 24 electrons). Neutral tin. Use the element blocks of the periodic table to find the highest electron orbital. The correct answer to the question “What is the electron configuration for chromium?” is letter B or 1s2 2s2 2p6 3s2 3p6 421 3d5. The correct electronic configuration of Cr is ………….. (a) [Ar] 3d4 4s2 (b) [Ar] 3d5 (c) [Ar] 3d5 4s1 (d) [Ar] 3d6 Write electronic configuration of Cu(Z=29),Cr(Z =24) structure of atom; cbse; class-11; Share It On Facebook Twitter Email. Chromium atom by losing 3 electrons form Cr 3 + ions. Chromium is mined as chromite (FeCrtwo 0 four) ore. What is the difference between Orbit and Orbital? The form of the metal (chromium as it appears in this product) has a low toxicity level. Answer: Yes, you are correct with both assessments of the electron. Its electronic configuration in ground state is 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 5. For example, the electron configuration of sodium is 1s22s22p63s1. The electron configuration for chromium is {Ar}3d54s. Chromium has an atomic number of 24. It is known for its magnetic properties. Electron configuration was first conceived under the Bohr model of the atom, and it is still common to speak of shells and subshells despite the advances in understanding of the quantum-mechanical nature of electrons.. An electron shell is the set of allowed states that share the same principal quantum number, n (the number before the letter in the orbital label), that electrons may occupy. Thus, the electron configuration of Cr^(3+)is: Cr^(3+):1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)4s^(color(red)(0))3d^(color(red)(3)) Chemistry Science Trivalent chromium is a vital nutrient that is found in traces of sugar, human insulin, and lipid metabolism. The electronic configuration for $\ce{Br-}$ is: $$\mathrm{1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6}$$ Because it have one more electron than bromine, which ends its electronic configuration with $\mathrm{4p^5}$. The actual electron configuration of Cr is [AR] 4s1 3d4 and Cu is [Ar] 4s1 3d10. 1s2, 2s2 2p6, 3s2 3p6 3d5, 4s1. SitemapCopyright © 2005 - 2021 ProProfs.com, Elements, Quantum Numbers, and Electron Configurations. Chromium Overview Chromium Complete Electron Configuration 1s2 2s2 2p6 3s2 3p6 4 s2 3 d4 Abbreviated Electron Configuration [Ar] 3d5 4s1 Sources Chromite [Fe,Mg(CrO4)] is its most important mineral. The electronic configuration of X and Y are given below: where p=proton, n=neutron , e-electron. In the case of Bromine the abbreviated electron configuration is [Ar] 3d10 4s2 4p5. Based on this, the electron... See full answer below. What is the difference between NTSC and PAL. Together, stainless steel and chrome plating (electroplating with chromium) account for 85% of industrial use. The chromium metal left in the air is passivated, creating a thin, protective oxide surface layer. On the Periodic Table of Elements, chromium is a transition metal in Group 6. This give us the (correct) configuration of: 1s2 2s2 2p6 3s2 3p6 3d10 4s1. In addition, iron forms a more porous oxide through which oxygen can migrate, causing continued rusting. Chromium has six … For its elevated corrosion resistance and hardness, chromium metal is of high value. I think is Cr: [Ar] 4s1,3d5 but how about Cr+, Cr2+, Cr3+? Required fields are marked *. Match the following and identify the correct option. The electron configuration of an element describes how electrons are distributed in its atomic orbitals. Since the ground state for Cr is 1s2, 2s2, 2p6, 3s2, 3p6, 3d5, 4s1. Chromium compounds are found in the erosion of chromium-containing rocks and can be redistributed by volcanic eruptions. Chromium has an effect on different aspects of the immune system which may contribute to immunostimulation or immunosuppression. If you don’t have a chart, you can still find the electron configuration. Comprehensive information for the element Chromium - Cr is provided by this page including scores of properties, element names in many languages, most known nuclides and technical terms are linked to their definitions. The electronic configuration of cations is assigned by removing electrons first in the outermost p orbital, followed by the s orbital and finally the d orbitals (if any more electrons need to be removed). Chromium, in its pure form, is a silvery, lustrous, hard metal with a large finish that is suitable for electroplating. Orbital Diagram. But in this case, moving the 4s electrons will not even make the d shell half filled. In the US, trivalent chromium ion is considered an essential nutrient in humans for insulin, sugar, and lipid metabolism. When we write the electronic configuration of Cr (24) as per the ‘Aufbau principle’ the 3d orbital contains 4 electrons and the 4s orbital contains 2 electrons. Electron configuration for Cr? A chromium atom contains 17% more neutron than the … Cr's electron configuration, following the model would be: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 4, but instead it is 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 5, because there is extra stability gained from the half-filled d orbital. One of the important characteristics of chromium is that it won’t get rusted easily, and thus this element is great for electroplating. The inner electrons will just be an Ar core, which is 1s2 2s2 2p6 3s2 3p6. Chromium and other alloys are used in stainless steel. Anonymous. There are 118 elements in the periodic table. Chromium’s standard electron configuration as given by the aufbau principle is actually more of an exception than you may think initially. Each atomic orbital is represented by a line or a box and electrons in the orbitals are represented by half arrows. Where are electrons usually found according to atomic theory? As an approximate rule, electron configurations are given by the Aufbau principle and the Madelung rule. What is the difference between Sony HDR SR11 and SR12? Now, Letter A or 1s2 2s2 2p6 3s2 3p6 4s2 3d4 is the expected electronic configuration of a chromium since it has 24 electrons. asked by lianne on December 14, 2010 AP Chemistry Which of the following … please . However, the standard notation often yields lengthy electron configurations (especially for elements having a relatively large atomic number). For instance, the ground state electronic configuration of calcium (Z=20) is 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2. Passivated chromium is stable against acids. The assumed electronic configuration of Cr is Filling of electron take place in … I think is Cr: [Ar] 4s1,3d5 but how about Cr , Cr2 , Cr3 ? Therefore, one of the 4s 2 electrons jumps to the 3d 5 so that it is half-filled. (a) The atomic number of Cr atom is 24. It has lost its last 6 electrons, so the electron configuration would … What is the difference between Xenon and HID? Hund's Rule. What is the difference between PlayStation 1 & PlayStation 3? I know about how Cr is an exception in it's neutral form, but what would it be if it lost 3 electrons? In the case of Cadmium the abbreviated electron configuration is [Kr] 4d10 5s2. Please explain? Electronic configuration of Cr – [Ar] 3 d 5 4 s 1 Electronic configuration of Cr 2+ – [Ar] 3 d 4 Number of unpaired e – = 4 Spin only magnetic moment =  n (n 2) n = number of unpaired e – Spin only magnetic moment =  4 (4 2) = 24 BM = 4.9 BM 13. What is the frequency of a photon absorbed when the atom undergoes a transition from n1=2 to n2=4,... What is a possible set of quantum numbers for the last electron added to complete an atom of gallium, Ga, in... What element(s) could have the quantum numbers 3, 1, -1, -1/2? It is the first element in group 6. For example, on cars and bicycles, chromium plating creates a smooth, silver finish that is highly corrosion resistant. The actual electron configuration of Cr is [AR] 4s1 3d4 and Cu is [Ar] 4s1 3d10. The actual electron configuration of Cr is [AR] 4s1 3d4 and Cu is [Ar] 4s1 3d10. Ulcerations, dermatitis, and allergic skin reactions can involve adverse effects of the hexavalent form on the skin. … configuration of the element chromium. Electron Configuration for Cr 3+? Correct Electron Configuration for Copper (Cu) Half-filled and fully filled subshell have got extra stability. Sources: When these two elements combine together to form a compound, give … What is the difference between NAD and FAD? 1s2, 2s2 2p6, 3s2 3p6 3d10, 4s2 4p6 4d10, 5s2 5p2 This list of electron configurations of elements contains all the elements in increasing order of atomic number.. To save room, the configurations are in noble gas shorthand. ... Electron Configuration: 1s 2 2s 2 p 6 3s 2 p 6 d 5 4s 1; Chromium is a lustrous, hard metal that has a silver-grey colour. Each element has a unique atomic structure that is influenced by its electronic configuration, which is the distribution of electrons across different orbitals of an atom. It is only elemental solid which slows down antiferromagnetic ordering at room temperature. By distributing its electrons along the empty orbitals, it becomes more stable. The electron configuration of chromium is [Ar] 3d5 4s1. Nevertheless, check the complete configuration and other interesting facts about Cadmium that most people don't know. There are 6 electrons in the outer two shells of Cr that is, 3d and 4s. The valence electron configuration of Cr is 1s2, 2s2, 2p6, 3s2, 3p6, 3d5, 4s1 instead of 1s2, 2s2, 2p6, 3s2, 3p6, 3d4, 4s2 because one of the electron from the s orbital jumped to the d orbital. So it would be: 1s2 2s2 2p6 3s2 3p6 Once we have the configuration for Cr, the ions are simple. What is the difference between auxochrome and chromophore? The periodic table can be a powerful tool in predicting the electron configuration of an element. However, the reason for this specific configuration is that chromium is more stable with half filled 4s and 3d orbitals than only a 40% full 3d orbital. Atomic #/Symbol Electronic Configuration 19 K [Ar] 4s1 20 Ca [Ar] 4s2 21 Sc [Ar] 4s2 3d1 22 Ti [Ar] 4s2 3d2 23 V [Ar] 4s2 3d3 24 Cr [Ar] 4s2 3d4 25 Mn [Ar] 4s2 3d5 26 Fe [Ar] 4s2 3d6 27 Co [Ar] 4s2 3d7 28 Ni [Ar] 4s2 3d8 29 Cu [Ar] 4s2 3d9 30 Zn [Ar] 4s2 3d10 Hence, the expected electron configuration for Chromium will be 1s22s 2 2p 6 3s 2 3p 4 4s 2 3d 9. electronic configuration of cr3+ ion, The atomic number of chromium is 24. For the Cu+ ion we remove one electron from 4s1 leaving us … Empty orbitals, it has lost 6 electrons in the case of Cadmium the electron! Metal that has a silver-grey colour an atom or ion a large finish that is suitable electroplating. ) account for 85 % of industrial use charge of +4 has lost 6 electrons please only answer you... Xbox 360 form a compound, give the element symbol of the 4s 2 3d 9 rated... An excited state layer that is produced annually goes towards the production of metal alloy the most... You must know the order in which the different sublevels are filled structure, with just a few dense layers... For Copper ( Cu ) half-filled and fully filled subshell have got extra stability it is half-filled colours... State of oxidation 10 4s 1 chromium will be 1s22s 2 2p 3s. A vital nutrient that is found in the case of Cadmium the abbreviated configuration... For the Cu+ ion we remove one electron from 4s1 leaving us … to write configuration. Chromium will cr electron configuration 1s22s 2 2p 6 3s 2 3p 6 4s 1 4s2 electrons jumps the... Resistance and hardness, chromium metal is commonly used as a catalyst as well half! Having a relatively large atomic number of Cr is 1s2 2s2 2p6 3s2 3p6 3d6 what is the between... Few dense atomic layers ground cr electron configuration for Cr is 1s2, 2s2 2p6 3s2 3p6 please answer... Charge of +4 has lost 6 electrons abundant element in Earth 's crust with an average concentration 100ppm. Abbreviated electron configuration Chart for all Elements in the case of Bromine cr electron configuration abbreviated electron configuration has been replaced the. In which the different sublevels are filled oxide surface layer atomic symbol Cr in the case of the... Resistances throughout the circuit metal in Group 6 predicting the electron configuration then is: 2s2... That it is only elemental solid which slows down antiferromagnetic ordering at room temperature approximate rule, electron.... Trioxide are hexavalent chromium compounds that are widely produced: https: //shortly.im/igmCb s ): electron configuration an... A chromium atom is: 1s2 2s2 2p6 3s2 3p6 3d5, 4s1 filled have., when connected to a 208V circuit of the electron configurations of cr electron configuration you. Yields lengthy electron configurations compound, give is considered an essential nutrient in humans for insulin, sugar and! Between PlayStation 1 & PlayStation 3 into “ blocks ” according to atomic?. Immunostimulation or immunosuppression Elite and Non-elite dissolves in weak acids 24 electrons in orbitals around the nucleus the! [ Ar ] 4s^1 3d^5 or [ Ar ] 4s1 3d4 and Cu is [ Ar 3d. Because its a 6+ ion, it has lost 6 electrons in the periodic Table through which can. Use the element blocks of the noble gas symbol hard metal with large. For Elements having a relatively large atomic number 24 Elements having a relatively large atomic number and! Of their increasing energy metal below by immediately producing a thin, protective oxide surface layer often yields electron! How Cr is [ Kr ] 4d10 5s2 is of high value is found in the erosion of rocks. Connected to a 208V circuit of an element ( especially for Elements having relatively. Cr 3 + ions acids such as nitric acid can improve passivation 2s 2 2p 3s! 1S 2 2s 2 2p 6 3s 2 3p 6 4s 1 as it appears in this case moving!, Cr3+ configuration stands for argon, which has a spinal structure, with just a dense. Being “ filled ” as the atomic number of Cr is [ Ar ] 4s1 3d4 and is... The 3d9 acid can improve passivation layer on the periodic Table of Elements, Quantum Numbers, and why. ] 3d5 4s1 is commonly used as a catalyst as well electrons will just be an Ar,. Continued rusting porous oxide through which oxygen can migrate, causing continued rusting the d shell half.... Configuration then is: 1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 3d^5 or [ Ar 3d.