Bohr’s Atomic Model & Line Spectrum
SK016Unit 2Past Year Examination QuestionsUnit 2: Atomic StructureBohr’s Atomic Model & Line SpectrumJan 991.What conclusion did Bohr draw in his atomic model to explain the line spectrum of hydrogen?2.The Brackett series of the spectral line of atomic hydrogen appears in the infrared region. Thewavelength for the third line in Brackett series is 2166 nm.i. Why the hydrogen atomic spectrum is in the form of lines?ii. Explain how the third line of the Brackett series is formed.iii. Calculate the energy involved to form the third line in the Brackett series. 9.18X10 20 Jun 993.The frequencies for the five lines in the Balmer series of the atomic hydrogen line emissionspectrum are as follows: 4.57, 6.17, 7.31, 7.55 and 7.71 ( x 1014 Hz)i.Copy the following diagram of energy levels and draw arrows to show the transitions ofelectron of hydrogen atom which correspond to the given frequency values.ii. Calculate the wavelength of the third line in the Balmer Series. 434nm n 8n 7n 6n 5n 4n 3n 2n 114
SK016Unit 2Past Year Examination QuestionsJun 004.State two main postulates from Bohr’s Atomic Theory and explain its main inadequacies.State the de Broglie’s postulate and Heisenberg Uncertainty Principle, and give theircorresponding equations.5.Explain the differences between Lyman series and Balmer series in an emission spectrum.Jan 006.Calculate the energy required to promote an electron from the first orbit to the third orbit of ahydrogen atom. 1.94X10-18 7What is meant by ionisation energy of hydrogen? Explain briefly how the ionisation energy ofhydrogen can be obtained from the spectral line of atomic hydrogen. Calculate the ionisationenergy of hydrogen in kJ mol 1. 1312 UPS 018.An electron of a hydrogen atom is excited to the energy level n 5 and drops to a lower levelenergy forming Paschen series.i. State the energy level whereby the electron ‘dropped back’. n 3 ii. Calculate the energy of the electron at the excited level. 8.72x10 20 iii. Calculate the energy emitted as a result of the transition. 1.55x10 19 9.Copy the following energy levels diagram and show the transitions of electrons that account forthe formation of the first, second and third line in the emission spectrum of hydrogen atom.Energyn 5n 4n 3n 2n 1a)Calculate the energy involved when the electron transits from the fourth orbit in order toform Balmer series. 4.09x10 19 b) State whether the energy is absorbed or released for this particular transition. Explain.Aug 0110.Calculate the wavelength of the third line in the Lyman series of hydrogen spectrum. 97.2 nm Determine the ionisation energy for 1 mole of hydrogen. 1312 15
SK016Unit 2Past Year Examination QuestionsAug 0211.One of the lines in the atomic hydrogen line emission spectrum falls in the visible light regionand has a wavelength of 410.2 nm.i. Explain the meaning of line spectrum.ii. Give the name for this spectrum series.iii. Determine the transition of the electron involved.MST Jun 0212.One of the lines in the Balmer series of the atomic hydrogen emission spectrum has awavelength of 486.2 nm.From which energy level does it drop from to give rise to this particular line?MST Jun 0313.a) State de Broglie’s postulates and Heisenberg Uncertainty principle.b) When a hydrogen atom absorbs energy, its electron is promoted to the 5th orbit. A linespectral is formed in the visible region resulting from the transition of the electron to alower energy orbit.Calculate the wavelength and energy of the emitted photon.Sept 0314.Explain the formation of line spectrum in the Balmer series of hydrogen atom.If the emitted photon has a wavelength of 434 nm, determine the transition of the electron thatoccurs.Calculate the energy of the line with the lowest energy in the Balmer series in kJ mol 1. 1.82x102 MST Jul 0415.a) Describe a continuous spectrum and explain how it differs from an atomic spectrum.b) Briefly describe what would occur when an electron in a hydrogen atom falls from anorbital to another with a lower energy.c) If the electron of a hydrogen atom had initially been in its 6th Bohr’s orbit, determine thefrequency of the electromagnetic radiation emitted if it forms a line spectral in thePaschen series.Oct 0416.Explain why an atomic emission spectrum consists of series of lines.MST Jul 0517.An electron of a hydrogen atom is excited to an energy level of n 7 and falls to a lower energylevel to produce Paschen series.i. State the energy level to which the electron falls.ii. Calculate the energy of the electron in the excited state.16
SK016Unit 2Past Year Examination QuestionsOct 0518.Figure below shows the line spectrum of hydrogen atom in the visible region.redblueindigo violetFrequencyi. Draw the energy levels in a hydrogen atom.ii. Show the electron transitions which produce the above lines.iii. Give the name of this particular series of lines.MST July 0619.i.Calculate the wavelength and frequency of the light that forms the third line of the Brackettseries.ii. Calculate the energy of an electron at its excited state before it drops to produce the secondline of the Balmer series.MST July 0720.(a) Give the difference between a line spectrum and a continuous spectrum.(b) An electron of a hydrogen atom is excited to the energy level n 4 and drops to a lowerenergy level to form a line in the Balmer series.i.Calculate the energy of the electron at the energy level n 4.ii.Determine the wavelength of this transition.Oct 0721. State the success and failure of Bohr s atomic model.Calculate the wavelength for a spectral line produced when an electron falls from n 5 to n 3.Name the series and state the region of electromagnetic spectrum for the line.Quantum Mechanics ModelJan 9922.a.b.c.With suitable examples, explain the meaning of the Pauli exclusion principle, Hund’srule and Aufbau principle.What is the meaning of orbital?Write the electronic configuration for 24Cr. Sketch the shape of the electron occupiedorbital in the outmost shell and describe its set of quantum numbers.Jun 9923.Draw the shapes of py and dxy orbitals. Show the symmetry and the coordinate axes in eachorbital diagram.State the quantum numbers for the 3dxy orbital.17
SK016Unit 2Past Year Examination Questions24.Orbitals of an atom can be recognised through a set of four quantum numbers whichcharacterise the orbitals.i. Name the four quantum numbers mentioned above and state the characters determined byeach quantum number.ii. Write the electronic configuration for 38Sr and give the corresponding values of all thefour quantum numbers for the electrons in the valence shell.Jan 0025.26.Explain why the following sets of quantum numbers are unacceptable in an atom.n 2, l 1, m 1, s 1n 3, l 1, m 2, s 1/2(2M)Given the following sets of quantum numbers for three electrons at the highest energy orbitalsfor an atom J.(3, 2, 0, - 12 ) , (3, 2, 1, 12 ) , (3, 2, 1, 12 )Describe the types of orbitals designated by the above sets of quantum numbers.Name the quantum number that determines the shape of the orbital.Give the electronic configuration and the orbital diagram for atom J. Hence, determine itsvalence shell.If five electrons were taken away from atom J, write the electronic configuration and the orbitaldiagram for the ion formed.State the type of stability for the electronic configuration of this ion.Jun 0027.For a multiple-electron atom, arrange the following orbitals in order of increasing energy:6p , 4d , 4s , 4f , 3p , 3d , 5s(1M)28.Write the electronic configuration in the ground state for Al and Ti .MST 0129.The table below shows the elements P, Q and R with their respective proton numbers.ElementProton numberP16Q25R28i. Give the electronic configuration and draw the orbital diagram for elements P and Q.ii. What is meant by orbital?iii. Draw the shapes of the orbitals that accommodate the valence electrons for elements Pand Q.iv. Compare the size of the atom P, Q and R. Explain.18
SK016Unit 2Past Year Examination Questions30.The table shows the proton numbers for five elements S, T, U, V and W.ElementSTUVWi.ii.iii.iv.Proton number7891113State the group and period for element U and W.Pick a block-p element.Predict the oxidation number for T and W.Arrange the elements S, T, U, V and W in order of increasing atomic radius. Explain.Mac 0131.Give the values of and m for orbitals 3p and 4d.Mac 0232.An element N has proton number 22. Explain how Hund’s rule, Pauli exclusion principle andAufbau principle are used in the placement of electrons into the orbitals for N.Draw the orbital diagrams for the four outermost electrons in element N. Hence, give thequantum number set for all these four electrons.MST Jul 0333.a) Write the electronic configuration for element 27X.b) State the four quantum numbers of the last electron being filled to the orbital accordingto Aufbau principle.MST Jul 0434.On appropriate coordinate axes, sketch out any two orbitals of an electron characterised by theprincipal quantum number of 3 and the azimuthal quantum number of 2.35.(a) Define an orbital. Sketch the shape of the orbital dxy2-y2 and dxy(b) State the electron configuration and orbital notation for chromium. What is the principleused in the arrangement of electron in an orbital. (Ar Cr : 24)(c) Calculate the wavelength and the energy of the third line in the Brackett series of thehydrogen spectrum.(d) State a value for n, l and m1 of an orbital in 4d sub-shell.Oct 0436.Copper is the ninth element in the first row of d-block of the Periodic Table.i. Write the electronic configuration of copper according to the Aufbau principle and theactual configuration as determined by experiments.ii. Give reason(s) for any anomaly.iii. Name another transition element which shows similar anomaly and write the electronicconfiguration showing the anomaly.19
SK016Unit 2Past Year Examination QuestionsMST Jul 0537.i. Define the terms orbit and orbital.ii. Chromium is an element in d-block of the periodic table. Write the electronicconfiguration of chromium. Explain the anomalous electronic configuration in chromium.iii. Give a set of quantum numbers for an electron in 3p-orbital.Oct 0538.State Aufbau principle and Hund’s rule. Based on the principle and rule above, show how theelectronic configuration of element 26G is built.Draw the dxy and dx2 y2 orbitals in 26G and the possible azimuthal and magnetic quantumnumbers for each of the orbital.MST Jul 0639.i. State the quantum number n , ℓ and m of the 3dx2- y2orbital and draw its shape.ii. Write the electronic configuration of Mn and Mn2 .Oct 0640.Write the electron configuration of iron(II) and iron(III). Determine the values of n , ℓ , m and sfor the electrons in the outermost shell in iron(III).Compare the size of these two ions.MST Jul 0741. The orbitals of the first two principal energy levels of atoms are shown below.XXYXYYZZZACBXXYYZZDEIn an atom of element J, orbitals A, B and E are full of electrons while orbitals C and D are halffull.i. State the charge of J ion. Briefly explain your answer.ii. Write the electronic configuration of J.iii. State the quantum number n, l and m for orbital D.20
SK016Unit 2Past Year Examination QuestionsOct 0742.Name the two transition elements that show anomaly in their electronic configurations.Write the electronic configuration and explain your answer.Oct 0843.i. A hydrogen atom requires a minimum energy of 2.18 x 10 – 18 J atom – 1 to remove an electronfrom its ground state level. Determine whether a blue-violet light with a wavelength of 434.0nm can affect this process.ii. The excited electrons of a group of irradiated hydrogen atoms are randomly scattered to n 1,2, 3, and 4 energy levels. Draw an energy level diagram to show all possible lines producedwhen all these electrons drop to lower levels. Identify the line which has the shortestwavelength.44.The proton number of elements J and K are 13 and 16 respectively. Draw the orbital diagramfor the valence electrons of each element. Suggest the most stable ions for J and K. write theirrespective electronic configurations.MST Jul 0945. a) FIGURE 2 shows the Lyman series of hydrogen emission spectrum.PQRFIGURE 2i) Draw the electronic transition of lines P, Q and R on the energy level diagram of thehydrogen atom.ii) Calculate the energy corresponding to line Q.b) The proton number of element T is 20.i) Write the electronic configuration of element T.ii) Predict the stable oxidation number of element T. Explain.iii) Draw the shape of orbital and give a set of quantum numbers for the valence electron.Oct 0946. Find the number of electrons in a zinc atom withi) orbital quantum number, l, equals to 1ii) magnetic quantum number, m, equals to -1iii) l 3 and m 1iv) s -1/247. Write an electronic configuration for argon and give two oppositely charged ions having the sameelectronic configuration as argon.State how a line spectrum differs from a continuous spectrum. Draw four lines in the visibleregion of the line spectrum of hydrogen and indicate the low and high energy ends.21
SK016Unit 2Past Year Examination QuestionsMST 2010/201148.(a)FIGURE 2 shows the Lyman series of hydrogen emission spectrum.QPRFIGURE 2(i)(ii)Explain why each successive line becomes closer to the previous one until the linesform a continuous.Calculate the frequency of the light that produce line Q[6 marks](b)Element M has 15 protons.Write the electronic configuration of M3Give a set of quantum numbers for an electron in the 3s orbitalState two differences between 2s and 3s orbitals(i)(ii)(iii)[ 4 marks]2010/201149.A line with a wavelength of 486.4 nm was observed in the Balmer series of the emissionspectrum of hydrogen.(i)(ii)(iii)50.Calculate its frequencyDetermine the initial and final values of the energy levels associated with thisemission.State the region of the electromagnetic spectrum in which the line is found.[5 marks]State and explain the appropriate rules used to determine the arrangement ofelectrons in atomic orbitals.The proton number of copper is 29. Write the valence electronic configuration of the copperatom. Give a set of quantum numbers for the valence electron that occupy the s orbital ofcopper.[8 marks]MST 2011/201251.(a)FIGURE 2 shows the Balmer series of hydrogen emission spectrum.ABCDEFIGURE 2(i)(ii)(iii)State the electron transition that produces line B.Explain the formation of line B.Calculate the energy of photon that produces line C with theWavelength of 434 nm.[6 marks]22
SK016Unit 2Past Year Examination Questions(b)The following sets of quantum numbers represent the 3 outermost electrons ofelement Y at ground state.(i)(ii)(iii)n 3 ℓ 0m 0 s 1/2n 3 ℓ 0m 0 s -1/2n 3 ℓ 1m 0s 1/2What is the maximum number of orbitals that exits in the shell n 3?Write the electronic configuration of element Y.Draw the shapes of orbitals for the valence electrons.[4 marks]2011/201252.(a)FIGURE 1 shows the Lyman series of the hydrogen line spectrum.10.97 10.6610.5210.279.748.22wave number (μm-1)FIGURE 1Describe the formation of the line emission spectrum of hydrogen atom in theLyman series. Calculate the ionization energy (kJmol-1) of the hydrogen atomusing FIGURE 1. Name two species that exhibit similar line spectrum as thatof hydrogen atom.[10 marks](b)For each of the following elements:Sodium, Magnesium, Alumunium and SiliconGive the formula, the type of bonding present and the acid base character ofits oxides. For those oxide(s) that exhibit amphoteric behaviour, write anappropriate chemical equation to illustrate the properties.[10 marks]2012/201353.(a)Describe the formation of emission spectrum for hydrogen atom. Showand label the first three series of electron transitions between energylevels.23
SK016Unit 2Past Year Examination QuestionsAn electron in a hydrogen atom is transferred from n 5 to n 3.Calculate the energy of the photon emitted and the wavelength of thespectral line produced.[8 marks](b)An element Q has proton number of 8. Draw the orbital diagram of theelement. Explain the two rules applied in arranging the electrons in theorbitals.[5 marks]MST 2012/201354.(a)FIGURE 1 shows the first four lines in the Brackett series of hydrogenemission spectrum.(i)State the region of the electromagnetic spectrum in which the series isfound.(ii)Which line corresponds to the shortest wavelength? Calculate thewavelength of the radiation that produces the line.[5 marks](b)E is an element with proton number of 21.(i)Write the electronic configuration of E.(ii)Draw the shapes of orbitals occupied by the valence electrons.(iii)Give the sets of quantum numbers for the electrons that occupy thefourth shell.[5 marks]MST 2013/201455.(a)In the hydrogen atom, an electron transition from a higher to a lower energylevel emits a photon with a wavelength of 1282 nm in Paschen series.(i)(ii)Determine the energy level of the exited state for this transition.State the radiation region for this transition.[5 marks]24
SK016Unit 2Past Year Examination Questions(b)Give the set of quantum numbers for the highest energy electron in atom X:(4, 1, 0, 1/2)(i)(ii)(iii)Write the electronic configuration of X.What is the most stable ion of X? Write its electronic configuration.Draw the shapes of orbitals occupied by the electrons with the highestprinciple quantum number in X.[5 marks]2013/201456.Bohr used the information from a line spectrum of a hydrogen atom toexplain the electronic structure of a one-electron system. A blue line in thespectrum of hydrogen atom was observed as a result of a transition ofelectron from the fourth to the second shells of an atom. What is meant bya line spectrum?. Calculate the wavelength and energy for this blue line.State two of Bohr’s postulates.[8 marks]MST 2014/201557.(a)Calculate the ionisation energy of hydrogen atom in KJ mol-1[4 mark](b)(c)State Heisenberg’s uncertainty principle.Give one Bohr’s postulate that is contradictory to the above principle.[2 mark]Two orbital diagrams for the electronic configurations shown below are notallowed. State the principle that are not obeyed and explain.(i)(ii)(i)2s2p(ii)[4 marks]2014/201558.The ion of atom X has 8 outermost electrons and 10 inner electrons with a charge of 1. Discuss all the rule(s) and principle(s) used to fill the electrons in the orbital ofatom X. Explain the change in the radius of atom X as it changes from a neutral atomto be negatively charged ion.Atom X, Y and Z are in periods n, n 1 and n 2, respectively. These atoms are alsoin the same group. Discuss the trend in electronegativity exhibited by these atoms.[20 marks]25
SK016Unit 2Past Year Examination QuestionsMST 2015/201659.(a)(b)(c)An electron of a hydrogen atom undergoes a transition to produce a line in thePachen series with a wavelength of 1094 nm.(i)(ii)State the region of the electromagnetic spectrum for the above wavelength.Determine the energy level of the excited state for this transition. State thetransition involved to form the emission.[ 4 marks](i)(ii)Define orbital.Write the electronic configuration of the valence electrons for arsenic,As(iii)Give a set of quantum numbers of one valence electron in the s orbital in(b)(ii)[ 4 marks]Draw and label one of the three-dimensional shapes of d orbitals whereelectron occupied the space that lie on the axes.[ 2 marks]2015/201660.Calculate the first three wavelenghts of the possible transitions of an electron in thePaschen series for a hydrogen atom. Show these wavelengths in a sketch of the linespectrum for this emission series. Explain how these transitions occurred.[10 marks]2016/201761.State the difference between the ground state and excited state of an electron in anatom.An electron of a hydrogen atom is excited to n 6 and falls to a lower energy levelforming the Paschen series. Calculate in kJ mol-1, the energy of the electron at theexcited level and the energy emitted as the result of the transition.Determine the shortest wavelength in nanometers (nm) in the Paschen series for thehydrogen atom.[10 marks]2017/201862.Sketch the energy level diagram to show the electronic transitions which give rise to the firstfive lines in the Lyman series of the hydrogen atom. Explain how a hydrogen line spectrum isobtained. Draw the resulting line spectrum.[10 marks]26
Bohr’s Atomic Model & Line Spectrum Jan 99 1. What conclusion did Bohr draw in his atomic model to explain the line spectrum of hydrogen? 2. The Brackett series of the spectral line of atomic hydrogen appears in the infrared region. The wavelength for the third line in Brackett series is 2166 nm. i.
NUCLEAR PHYSICS - REVIEW . Atomic structure. . Bohr's atomic model is an updated version of Rutherford's model. The main difference between the two is that Bohr's model is based of Bohr’s Model – atomic energy levels theories and lessons from quantum
The Bohr model can be applied quite successfully to such hydrogen-like ions as singly ionized helium and doubly ionized lithium. Bohr Model The first application of the quantum theory of atomic structure was made in 1913 by Niels Bohr. Bohr developed a model of the hydrogen atom, which allowed him to explain why the observed .
1 \usepackage{bohr} The main command, \bohr, creates the models: \bohr[hnum of shellsi]{hnum of electronsi}{hatom namei} The main command. The mandatory arguments take the number of electrons to be printed and the atom symbol that is printed in the center. This is described best by an example: 1 \bohr{3}{Li} Li There is not much more to it.
by Bohr. The Bohr model works well for explaining the line spectra for the hydrogen atom, which contains only a single electron, but the model represented by Eq. (5) fails when applied to multi-electron atoms. In this lab you will use spectroscopy to evaluate the Bohr model for the hydrogen atom, and to exami
Sep 05, 2014 · How does the Bohr model improve upon the Rutherford model? The Rutherford model could not explain why elements that have been heated to higher and higher temperatures give off different colors of light. The Bohr model explains how the energy levels of electrons in an atom change when the atom emits light. 5.1 Revising the Atomic Model
Bohr showed that he was a better than average physicists by suggesting multiple improvements to the experiments being done in Rutherford's lab. Eventually Bohr was even able to suggest an answer to the problem with Rutherford's Planetary model. Bohr was able to take two ideas and put them together to come up with his model. 1.
Ancient atomic theory for the universe - Democritus & Epicurus (after 400 bC) Dalton atomic model (billiard ball model, 1803) Thomson atomic model . (Rutherford-Bohr model, 1913) Modern quantum mechanics (Heisenberg et al, 1927) TODAY. Timeline of Atomic Models 2 Democritus (460 b.C. - 370 b.C.): "Matter could not be divided into .
language of instruction was a common problem identified by many. Based on this issue a research investigation with the aim of raising teacher awareness of the strategies and techniques that could be used to support the language development of young learners was conducted. The Research Investigation . In 2010, a research project funded by a grant from the Jeff Thompson Award, was conducted to .
