Quantum Physics Lesson 4

Slides:



Advertisements
Similar presentations
Chemistry Daily 10’s Week 5.
Advertisements

Aim: How can we explain energy transitions in an atom? Do Now: What were the limitations of the Rutherford model of the atom and how did the Bohr model.
e-e- E n eV n = 1 ground state n = 3 0 n = ∞ n = n = 4 ionisation N.B. All energies are NEGATIVE. REASON: The maximum energy.
Quantum Physics ISAT 241 Analytical Methods III Fall 2003 David J. Lawrence.
Wave-Particle Duality: The Beginnings of Quantum Mechanics
About these slides These slides are used as part of my lessons and shouldn’t be considered comprehensive There’s no excuse for not turning up to lessons!
Wave-Particle Duality 1: The Beginnings of Quantum Mechanics.
Objectives To understand how the emission spectrum of hydrogen demonstrates the quantized nature of energy To learn about Bohr’s model of the hydrogen.
Electron Configuration and Energy Levels: Ground state: All the electrons in an atom have the lowest possible energies Most stable electron configuration.
Electrons And Light. Electromagnetic Radiation Energy that travels as a wave through space Wavelength –λ – distance between corresponding points on adjacent.
Lecture 2110/24/05. Light Emission vs. Absorption Black body.
Advanced Higher Chemistry
Cutnell/Johnson Physics 7 th edition Classroom Response System Questions Chapter 39 More about Matter Waves Reading Quiz Questions.
Wave-Particle Duality 1: The Beginnings of Quantum Mechanics.
E = hf E – energy of a quantum (Joules) h – Plank’s constant (6.626 x J  s) f – frequency of absorbed or emitted EMR.
E = hf E – energy of a quantum (Joules) h – Plank’s constant (6.626 x J  s) f – frequency of absorbed or emitted EMR.
Title: Lesson 2 The EM Spectrum and Emission Line Spectra
PACS 2008 Unit: Atomic Structures Mr. Nylen Pulaski Academy High School 2008.
3.4 Energy levels in atoms Electrons in atoms
Particle Nature of Light
Emission Spectrum Animation
Properties of Light.
Nature of Light chapter s – 1900s Is Light a wave or a stream of particles.
Electron Energy and Radiation Quantum Mechanics and Electron Movement.
Bohr’s Model of the Atom Scientists noticed that the laws of Classical Physics that applied to large objects did not seem to be able to explain.
Wave-Particle Duality: The Beginnings of Quantum Mechanics.
Wave-Particle Duality: The Beginnings of Quantum Mechanics.
How to Make Starlight (part 1) Chapter 7. Origin of light Light (electromagnetic radiation) is just a changing electric and magnetic field. Changing electric.
Blackbody Spectrum Remember that EMR is characterized by wavelength (frequency) Spectrum: distribution of wavelength (or frequency) of some EMR Blackbody:
Aim: How to distinguish electrons in the excited state
Electrons Negative charge e- Located in the electron cloud far from the nucleus Have mass, but it is negligible Also have wave-like properties.
Warm-Up Lithium has an atomic weight of g/mol. When g of lithium is heated, it emits an energy measured at 262,500 joules. What is the energy.
Chapter 28:Atomic Physics
Sydney Opera House Opens (1973) READING: Chapter 8 sections 1 – 2 READING: Chapter 8 sections 1 – 2 HOMEWORK – DUE TUESDAY 10/20/15 HOMEWORK – DUE TUESDAY.
Atoms and Spectra. What do we know ? We know that the electrons in an atom orbit the nucleus. We also know that a gas will emit a line spectrum when an.
atomic excitation and ionisation
Electromagnetic Spectrum Section 1 The Development of a New Atomic Model Chapter 4.
1.6.  A spectroscope separates light into its component wavelengths, revealing a line spectrum that is unique to each element.
Atoms & Nuclei The Structure of the Atom. Atoms are made up of a dense, positively charged nucleus and negatively charged electrons that orbit in specific.
AtomsSection 3 Modern Models of the Atom 〉 What is the modern model of the atom? 〉 In the modern atomic model, electrons can be found only in certain energy.
A100 Movie Special Tuesday, March 23 Swain West 119 7:00 pm (153 minutes) Winner of several awards 20 activity points! BYOP (Bring Your Own Popcorn)
Section 11.2 The Hydrogen Atom 1.To understand how the emission spectrum of hydrogen demonstrates the quantized nature of energy 2.To learn about Bohr’s.
Wave-Particle Duality JJ Thomson won the Nobel prize for describing the electron as a particle. His son, George Thomson won the Nobel prize for describing.
CHAPTER 2 ATOMIC STRUCTURE 2.1 Bohr's atomic model 2.2 Electronic configuration.
Line Spectra When the particles in the solid, liquid, or gas accelerate, they will produce EM waves. Electron orbit to orbit transitions in atoms (gasses)
QUANTUM AND NUCLEAR PHYSICS. Wave Particle Duality In some situations light exhibits properties that are wave-like or particle like. Light does not show.
1 Mr. ShieldsRegents Chemistry U06 L02 2 H2H2H2H2 We saw that Bohr Was able to equate orbits With Energy levels And secondly he could Then equate energy.
Light 1)Electrons (charged –1 each, with a mass of 1/1836 amu each) surround the nucleus of the atom in distinct energy levels. Electrons occupy the.
Read Summary Notes, page 69, “Emission Spectra.” 30/09/2016 Background to Spectra. Continuous spectra In a continuous spectrum all frequencies of radiation.
Where do these spectral lines come from?
Bohr Model Of Atom.
Homework #3 will be posted on Wednesday
Physics and the Quantum Mechanical Model
On the white boards Draw out the basic structure of an atom Add labels
Wave-Particle Duality
The Bohr Model (1913) revolve sun energy
Neils Bohr.
Atomic Emission Spectrum
Spectra and Energy Levels in Atoms
Emission Spectrum Animation
Energy and Electrons energy
Orbits and Line Spectra
Section 3: Modern Atomic Theory
Bohr, Emissions, and Spectra
Absorption & Emission.
Key Areas covered The bohr model of the atom
Section 3: Modern Atomic Theory
Flame tests.
Quantum Physics Lesson 4
Atoms.
Presentation transcript:

Quantum Physics Lesson 4 Energy Levels Quantum Physics Lesson 4

Learning Objectives Explain what is meant by the term energy level. Describe what happens when excited atoms de-excite. Calculate the energy of emitted photons using the equation hf = E1 - E2. Explain how a fluorescent tube works  HWK

Homework Use books and the internet to research how fluorescent tubes work. How do fluorescent tubes work? Why are they used? Use the words electrons, atoms, photons, ionisation and excitation in your answer. Do not copy and paste  put in your own words! Reference your work properly.

What is Quantisation? Calculate the gravitational potential energy of your sweet to win it. Notice that each sweet can only have a certain specific energy determined by the flat surfaces in the room. When something can only take certain discrete values we say it is quantised e.g. shoe size.

Definitions Ground State The lowest energy level of an atom. Excited State An energy input raises the electrons to higher energy levels. The lowest energy level of an atom. When one or more of an atom’s electrons moves to an outer shell at higher energy.

Energy Levels The electrons in an atom are trapped because they are attracted to the protons in the nucleus. Their energies are determined by which shell they are in: nearer the nucleus = less energy. But just like the sweets resting on the desk, each electron can only take certain discrete energies which correspond to the shells or orbits.

Video BBC The Atom – Jim Al-Khalili 3/6 0:00-9:10

Quantisation A quantum mechanical system or particle that is bound, confined spatially, can only take on certain discrete values of energy, as opposed to classical particles, which can have any energy. These values are called energy levels. The term is most commonly used for the energy levels of electrons in atoms or molecules, which are bound by the electric field of the nucleus. The energy spectrum of a system with energy levels is said to be quantised.

Energy Levels “Why do the states have negative energy?” This is because the zero of energy is considered to be that of a free electron 'just outside' the atom. All energy states 'below' this – i.e. within the atom are therefore negative. Energy must be put into the atom to raise the electron to the 'surface' of the atom and allow it to escape.

Well Analogy Imagine you are stuck down a hole…with a number of ledges. You could try to jump to get out but unless you jump high enough to reach one of the ledges you will just fall back down  releasing energy as sound energy. It’s a bit like this in the atom the electrons need the ionisation energy to get out.

De-excitation Whenever these is a vacancy in a shell an electron from a outer shell moves down to fill it. When this happens the electron emits a photon. The photon has an energy equal to the difference between the energy levels.

De-excitation

Equation In words:- In Symbols:- Note that E1 and E2 refer to the energies of the energy levels and hf is the energy of the photon emitted when an electron falls from the higher level to the lower level.

Excitation using Photons An electron in an atom can absorb a photon and move to a higher energy level  But only if the photon energy matches the difference between the energy levels. This is not true for ionisation; as long as the energy of the incoming photon is greater than the ionisation energy, the electron can escape.

Electron in orbit round a nucleus in an atom Energy input. The electron is excited and rises to a higher energy level (shell). The electron falls back to its original energy level and energy is emitted in the form of radiation. The bigger the drop the greater the energy emitted and the shorter wavelength the radiation has (blue light).

Fluorescence When an electron in a higher energy level de-excites it can either:- Go straight down to the ground state  one photon. Cascade down several energy levels  several photons, each of lower energy. An atom can absorb UV but emit visible light.

The energy levels and spectra series