Bohr's Study of Spectra and Hydrogen Spectrum
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Questions and Answers

Match the following elements with their corresponding flame colors:

Lithium = Crimson Potassium = Lilac Barium = Green Sodium = Yellow

Match the following terms related to Bohr's theory with their definitions:

Quantum of energy = Fixed amount of energy an electron can have Orbits = Fixed paths of electrons around the nucleus Ground state = Lowest energy state of an atom Energy levels = Represented by the letter ‘n’

Match the following tools with their uses in spectroscopy:

Spectrometer = Measures wavelengths of light Spectroscope = Views spectra Hydrogen Gas Discharge Tube = Produces emission spectrum Prism = Breaks white light into a spectrum

Match the following statements about emission spectra:

<p>Each element = Has its own unique emission spectrum Emission spectrum = Consists of narrow colored lines Spectra measurement = Uses a spectrometer Bohr's insight = Informed the arrangement of electrons</p> Signup and view all the answers

Match the following elements with their flame test colors:

<p>Barium = Green Lithium = Crimson Sodium = Yellow Potassium = Lilac</p> Signup and view all the answers

Match the following colors with their corresponding salts during flame tests:

<p>Crimson = Lithium Lilac = Potassium Green = Barium Blue green = Copper</p> Signup and view all the answers

Match the following energy levels with their values:

<p>n = 1 = Lowest energy level n = 2 = First excited state n = 3 = Second excited state n = 4 = Third excited state</p> Signup and view all the answers

Match the following scientists with their contributions:

<p>Niels Bohr = Energy levels in the hydrogen atom Werner Heisenberg = Uncertainty principle J.J. Thomson = Plum pudding model Robert Millikan = Charge of the electron</p> Signup and view all the answers

Match the following types of spectra with their descriptions:

<p>Continuous spectrum = Array of colors from white light Emission spectrum = Narrow bands of light from specific elements Absorption spectrum = Dark lines indicating absorbed wavelengths Line spectrum = Characteristic of individual elements</p> Signup and view all the answers

Match the following atomic terms with their definitions:

<p>Energy level = Fixed energy of an electron in an atom Atomic orbital = Region in space for finding an electron Electron configuration = Distribution of electrons in atomic orbitals Ionization energy = Energy required to remove an electron</p> Signup and view all the answers

Match the following concepts from Bohr's theory with their significance:

<p>Energy quantization = Electrons can only exist in certain energies Electron orbits = Fixed paths determine allowed energies Emission spectroscopy = Identification of elements based on light Flame tests = Identification based on flame color</p> Signup and view all the answers

Match the following electron configurations with their corresponding elements:

<p>Silicon = 1s2 2s2 2p6 3s2 3p2 Iron = 1s2 2s2 2p6 3s2 3p6 4s2 3d6 Oxygen = 1s2 2s2 2p4 Carbon = 1s2 2s2 2p2</p> Signup and view all the answers

Match the following concepts with their meanings:

<p>Plum pudding model = Mass of positively-charged material with electrons Heisenberg's Uncertainty principle = Position and velocity of an electron cannot be known simultaneously Millikan's oil drop experiment = To measure the charge on an electron Atomic orbital = High probability region for finding electrons</p> Signup and view all the answers

Match the following terms with their definitions:

<p>Ground State = Lowest available energy level of electrons Excited State = Higher energy levels than those in the ground state Photon = Particle of light emitted when an electron falls Energy Level = Fixed energy value that an electron may have</p> Signup and view all the answers

Match the following equations with their meanings:

<p>E2 – E1 = hf = Difference in energy between excited and ground state hf = Energy of the emitted photon h = Planck’s constant f = Frequency of emitted light</p> Signup and view all the answers

Match the following processes with their descriptions:

<p>Light Absorption = Atoms in ground state absorb specific wavelengths of light Emission Spectrum = Spectrum of light emitted when electrons fall to lower energy levels Atomic Absorption Spectrum = Spectrum with certain wavelengths missing after light passes through a gas Balmer Series = Emission lines resulting from electrons falling to the n=2 energy level</p> Signup and view all the answers

Match the following uses of Atomic Absorption Spectrometry (AAS) with their applications:

<p>Water Analysis = Measurement of metals like lead and mercury Blood Samples = Testing concentration of lead in people Forensic Science = Testing for gunshot residue on skin Environmental Monitoring = Analyzing water for hazardous pollutants</p> Signup and view all the answers

Match the following components with their roles in the Atomic Absorption Spectrometer:

<p>Light Source = Provides specific wavelength light for absorption Sample Chamber = Holds the gaseous sample of the element Detector = Measures the intensity of transmitted light Monochromator = Isolates specific wavelengths of light</p> Signup and view all the answers

Match the following spectral phenomena with their characteristics:

<p>Absorption Spectra = Shows missing wavelengths from transmitted light Emission Spectra = Shows wavelengths emitted by excited electrons Line Spectrum = Indicates specific energy values electrons can possess Continuous Spectrum = Contains a full range of wavelengths without gaps</p> Signup and view all the answers

Match the following energy levels with the number of sublevels:

<p>n = 1 = 1 sublevel n = 2 = 2 sublevels n = 3 = 3 sublevels n = 4 = 4 sublevels</p> Signup and view all the answers

Match the following orbitals with their shapes:

<p>s orbital = Spherical p orbital = Dumbbell d orbital = Complex (not defined in the content) f orbital = Complex (not defined in the content)</p> Signup and view all the answers

Match the following elements to their study relevance using AAS:

<p>Lead = Toxic metal analyzed in blood and water Mercury = Heavy metal measured for environmental safety Cadmium = Element often found in industrial contamination Carbon = Not generally measured using AAS techniques</p> Signup and view all the answers

Match the following concepts with their corresponding scientific principles:

<p>Photon Emission = Occurs when electrons return to ground state Spectral Lines = Result from specific energy transitions Energy Absorption = Necessary for electrons to reach higher energy levels Quantum States = Discrete energy levels available to electrons</p> Signup and view all the answers

Match the following sublevels with their total number of electrons:

<p>s sublevel = 2 electrons p sublevel = 6 electrons d sublevel = 10 electrons f sublevel = 14 electrons (not defined in the content)</p> Signup and view all the answers

Match the following concepts with their descriptions:

<p>Sublevel = Subdivision of a main energy level Orbital = Region of high probability of finding an electron Emission spectra = Light spectrum emitted by elements Wave nature = Wave motion associated with moving particles</p> Signup and view all the answers

Match the following limitations of Bohr's theory:

<p>Failed for multi-electron atoms = Not accounting for lines in spectra Does not consider wave motion = Limited to hydrogen Does not explain line splitting = Cannot determine both position and velocity Assumes electrons as particles = Contradicted by wave nature</p> Signup and view all the answers

Match the following descriptions to their corresponding orbital count:

<p>1 orbital = s sublevel 3 orbitals = p sublevel 5 orbitals = d sublevel 7 orbitals = f sublevel (not defined in the content)</p> Signup and view all the answers

Study Notes

Bohr's Study of Spectra

  • White light broken down into colours by a glass prism creates a continuous spectrum
  • Bohr studied a hydrogen gas discharge tube through a prism, showing narrow coloured lines (emission spectrum)

Hydrogen Spectrum

  • Emission spectra are important in chemistry
  • Each element has a unique emission spectrum used for identification
  • A spectrometer measures wavelengths of light bands
  • A spectroscope views spectra but cannot measure wavelengths

Mandatory Experiment Number 1

  • Flame tests with salts of lithium, sodium, potassium, barium, strontium, and copper
  • Damp wooden splint holds a sample of salt in a Bunsen burner flame
  • Record the colour of the flame for each salt
Metal Flame Colour
Lithium Crimson
Potassium Lilac
Barium Green
Strontium Red
Copper Blue-green
Sodium Yellow

The Bohr Theory

  • Electrons in an atom have fixed energy levels (quantised energy)
  • Electrons orbit the nucleus in fixed paths (orbits/energy levels)
  • The lowest energy level is n = 1
  • Electrons don't gain or lose energy while in an energy level
  • Atoms usually exist in a ground state (lowest available energy levels)
  • Energy absorption causes electrons to move to higher energy levels (excited state)
  • Energy absorbed = difference in energy between ground and excited states
  • Electrons in excited state return to ground state, emitting light with a specific frequency/colour
  • Frequency of emitted light depends on energy difference between levels (E2- E1 = hf)
  • Each frequency of light appears as a coloured line on the spectrum

Atomic Absorption Spectrometry (AAS)

  • Atoms absorb light at specific wavelengths
  • If light passes through a gaseous sample of an element, some wavelengths will be missing which are specific to the elements’ unique absorption spectrum
  • The missing wavelengths correspond to those absorbed by atoms in ground state
  • Atoms absorb the same radiation as they emit in an excited state

Uses of AAS

  • Analysing water for metals (lead, mercury, cadmium)
  • Measuring lead in blood samples
  • Forensic science (gunshot residue)

Energy Sublevels

  • Every energy level has several sublevels where electrons can be
  • Sublevels are subdivisions of a main energy level, with similar energy
  • The number of sublevels is equal to the energy level number

Wave Nature of the Electron

  • Electrons have wave properties
  • Heisenberg's Uncertainty Principle - velocity and position of electrons cannot be measured simultaneously
  • Bohr's theory worked for hydrogen, but not complex atoms
  • Bohr's theory didn't account for spectral lines splitting or electron wave motion

Atomic Orbitals

  • Orbitals are locations within space where an electron is most likely to be found
  • 's' orbitals are spherical
  • 'p' orbitals are dumbbell-shaped.

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Description

Explore Bohr's research on the emission spectra and the unique color signatures of different metal salts. Understand how flame tests reveal the distinct colors emitted by elements and how this relates to their identification in chemistry. Delve into the quantized energy levels of electrons in atoms as per Bohr's theory.

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