Bohr's Model and Flame Tests in Chemistry

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Questions and Answers

What is the term used to describe the specific paths that electrons follow around the nucleus?

Energy shells

Quantum levels

Energy bands

Orbits (correct)

In which state do atoms have the lowest possible amount of energy?

Excited state

Ground state (correct)

Ionized state

Free state

What occurs when an electron absorbs energy and moves to a higher energy level?

Ionization

Photon emission

Excitation (correct)

Condensation

How is the energy of the electron in a particular orbit characterized according to Bohr's theory?

It's defined by n. Signup and view all the answers

What type of spectrum is produced when light from a Hydrogen Gas Discharge Tube is passed through a prism?

Emission spectrum Signup and view all the answers

What device is used to measure the wavelength of the bands of light in a spectrum?

Spectrometer Signup and view all the answers

What happens to an electron in an atom when it is in an excited state?

It gains energy and occupies a higher orbit. Signup and view all the answers

Which of the following elements would produce a crimson flame during a flame test?

Lithium Signup and view all the answers

What occurs when energy is supplied to an atom in its ground state?

Electrons absorb energy and jump to higher energy levels. Signup and view all the answers

Which statement correctly defines the ground state of an atom?

Electrons occupy the lowest available energy levels. Signup and view all the answers

What happens to the excess energy when an electron falls back to the ground state?

It is emitted as a photon of light. Signup and view all the answers

What is the relationship between the energy levels and the frequency of emitted light?

Frequency is directly proportional to the energy difference between levels. Signup and view all the answers

What is an Atomic Absorption Spectrum?

A spectrum with certain wavelengths missing, representing absorbed light. Signup and view all the answers

Which of the following is NOT a use of Atomic Absorption Spectrometry?

Determining the size of atoms. Signup and view all the answers

What principle does an Atomic Absorption Spectrometer operate on?

Atoms emit and absorb light at the same characteristic wavelengths. Signup and view all the answers

Which emissions line series is responsible for the emission of visible light when electrons fall to the n=2 energy level?

Balmer Series Signup and view all the answers

What defines a sublevel in an energy level?

It is a subdivision of a main energy level consisting of multiple orbitals with the same energy. Signup and view all the answers

How does the number of sublevels relate to the main energy level denoted as 'n'?

The number of sublevels is equal to the value of n. Signup and view all the answers

What is the significance of the wave-particle duality of electrons?

It implies that electrons have both wave and particle characteristics. Signup and view all the answers

What limitation does Bohr’s theory have concerning multi-electron atoms?

It fails to account for all lines in the emission spectra. Signup and view all the answers

What shape is described by a 'p' orbital?

Dumbbell Signup and view all the answers

What does the Uncertainty Principle state regarding electrons?

It is impossible to measure speed and position simultaneously. Signup and view all the answers

How many total electrons can be found in an 's' sublevel?

2 Signup and view all the answers

In atomic absorption spectrometry, what is the relationship between light absorption and element concentration?

Directly proportional. Signup and view all the answers

Study Notes

Bohr's Model of the Atom

Bohr, a Danish scientist, explained electron arrangement in atoms.
When white light passes through a prism, it separates into a spectrum of colors (continuous spectrum).
Bohr observed that light from hydrogen gas produced a line spectrum (discrete colors).
Each element has a unique emission spectrum, useful for identification.
Spectrometers measure wavelengths of light bands in spectra.
Spectroscopes display spectra but don't measure wavelengths.

Flame Tests

Flame tests identify elements.
Damp wooden splints hold samples in a Bunsen burner flame.
Record the color of flames for each element:
- Lithium – Crimson
- Potassium – Lilac
- Barium – Green
- Strontium – Red
- Copper – Blue-green
- Sodium – Yellow

The Bohr Theory

Electrons orbit the nucleus in fixed energy levels (orbits).
Electrons in a given level possess a fixed amount of energy.
Energy levels are represented by 'n' (lowest is 'n=1').
Electrons neither gain nor lose energy, while in a single energy level.
Atoms normally exist in the ground state (lowest energy).
Electrons can jump to higher energy levels (excited state) when absorbing energy.
Absorbed energy equals the difference in energy between excited state and ground state.
Electrons fall back emitting light with specific energies and corresponding colors.
Frequency of emitted light depends on the difference in energy between levels.
The energy difference is 'E₂ - E₁ = hf'.
Coloured lines in spectra represent unique emitted frequencies from atoms.

Atomic Absorption Spectrometry (AAS)

Atoms absorb specific wavelengths of light.
This results in missing bands in a light spectrum passed through a gas sample.
The absorbed wavelengths match emission wavelengths of excited atoms.
AAS measures absorption spectra and is used to measure element concentrations.
Applications include water analysis, measuring lead in blood, forensic science.

Energy Sublevels

Energy levels (except 'n=1') are divided into sublevels.
Sublevels are subdivisions within an energy level, of equal energy.
Number of sublevels equals the value of 'n'.
Examples: 'n=2' has 's' and 'p' sublevels, 'n=3' has 's', 'p', and 'd' sublevels.

Wave Nature of Electrons

Electrons exhibit wave-like properties (wave-particle duality).
This means electrons have a wave motion.
This was mathematically described by de Broglie.

Heisenberg's Uncertainty Principle

It's impossible to precisely determine an electron's position and velocity simultaneously.
This limitation led to refinements of the Bohr model.

Atomic Orbitals

Orbitals are regions with high chance of finding electrons.
's' orbitals are spherical, 'p' are dumbbell-shaped
Elements have a corresponding number of electrons in each orbital.
Atomic orbitals and their shapes describe the distribution of electrons in an atom.

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Description

Explore the fascinating concepts of Bohr's model of the atom and the practical applications of flame tests in identifying elements. This quiz covers the principles of electron arrangement, emission spectra, and the unique colors produced by various elements in flame tests. Test your knowledge and understanding of these fundamental topics in chemistry.