Electrons in Atoms.

Slides:



Advertisements
Similar presentations
Ch. 13 Electrons in Atoms Ch Models of the Atom
Advertisements

Electrons and Quantum Mechanics
Chemistry Chapter 5.
Chapter 13 Electrons in Atoms
Chapter 13 Electrons in Atoms
Chapter 4 Electron Configurations. Early thoughts Much understanding of electron behavior comes from studies of how light interacts with matter. Early.
Electron Configuration
Electronic Configurations of Atoms
Chapter 5 : Electrons in Atoms. Problems with Rutherford’s Model Chlorine # 17 Reactive Potassium # 19 Very reactive Argon # 18 Not reactive.
Electrons in Atoms Chapter 5. Duality of Light Einstein proved that matter and energy are related E = mc 2 Einstein proved that matter and energy are.
Electrons in Atoms. Models of the Atom – A History John Dalton John Dalton atom was solid, indivisible mass atom was solid, indivisible mass J.J. Thomson.
Electrons in Atoms Chapter 5 General Chemistry. Objectives Understand that matter has properties of both particles and waves. Describe the electromagnetic.
Chapter 13 Electrons in Atoms C. Smith. I. Models of the Atom A. The Evolution of Atomic Models 1. There are four major models of the atom that have been.
Chapter 4 Arrangement of Electrons in Atoms. 4-1 The Development of the New Atomic Model Rutherford’s atomic model – nucleus surrounded by fast- moving.
Electrons in atoms Chapter5 Waves Light travels as both Waves and Packets of energy. Light is a form of Electromagnetic Radiation. –EM Radiation has.
End Show Slide 1 of 20 Ch. 5: Models of the Atom What you need to know: Chapter 5 Timeline pp (theory and people) Definitions: quantum mechanical.
Unanswered Questions Rutherford’s model did not address the following questions: What is the arrangement of electrons in the atom? What keeps the electrons.
Unanswered Questions Rutherford’s model did not address the following questions: 1. What is the arrangement of electrons in the atom? 2. What keeps the.
Electrons in Atoms Chapter Wave Nature of Light  Electromagnetic Radiation is a form of energy that exhibits wavelike behavior as it travels through.
Chapter 5: Electrons in Atoms
The Development of A New Atomic Model
Unit 4 Energy and the Quantum Theory. I.Radiant Energy Light – electrons are understood by comparing to light 1. radiant energy 2. travels through space.
CHAPTER 11 NOTES MODERN ATOMIC THEORY RUTHERFORD’S MODEL COULD NOT EXPLAIN THE CHEMICAL PROPERTIES OF ELEMENTS.
E LECTRONS IN A TOMS Chapter 5. L IGHT AND Q UANTIZED E NERGY Nuclear atom and unanswered questions Scientists found Rutherford’s nuclear atomic model.
Chapter 4 Electron Configurations. Waves Today scientists recognize light has properties of waves and particles Waves: light is electromagnetic radiation.
Light Light is a kind of electromagnetic radiation, which is a from of energy that exhibits wavelike behavior as it travels through space. Other forms.
CHAPTER 4 CHEMISTRY. PROPERTIES OF LIGHT (P91-93) Originally thought to be a wave It is one type of ELECTROMAGNETIC RADIATION (exhibits wavelike behavior.
UNIT 10 LIGHT & ELECTRONS S.Fleck Unit Objectives Calculate the wavelength, frequency, or energy of light, given two of these values Explain.
Ch. 5 Electrons in Atoms Objective: Understand where electrons are located within an atom, and the scientific progression to determine the location of.
Electrons in Atoms Big Idea #2 Electrons and the Structure of Atoms
Physics and the Quantum
Chapter 4 Electrons In Atoms.
Wave-Particle Nature of Light
Which scientist developed the quantum mechanical model of the atom?
Chapter 13 Quantum-Mechanical Model -explains how e- exist in atoms and how close those e- determine the chemical and physical properties of elements -already.
Click a hyperlink or folder tab to view the corresponding slides.
LT1: Electron Arrangement (Ch. 5)
5-1 Quantum Theory of the atom
LT1: Electron Arrangement (Ch. 5)
The Atom and Unanswered Questions
Chapter 13 Electrons in Atoms.
Chapter 13 Electrons in Atoms.
Physics and the Quantum Mechanical Model
Electronic Structure and Light
2.4 Modern Atomic Structure Objectives 4, 5:b, and 6:a
Chapter 5 Arrangement of electrons in atoms
Chapter 5 Notes Electrons.
Quantum Theory.
Electromagnetic spectrum
Chapter 5 - Electrons in Atoms
Which scientist developed the quantum mechanical model of the atom?
Arrangement of electrons
Electrons in Atoms Chapter 5.
Chapter 5 Electrons in Atoms.
Quantum Theory and the Atom
Physics and the Quantum Mechanical Model
“Electrons in the Atom”
Chemistry Chapter 4 Notes
Electrons in Atoms Chapter 5.
Section 5.3 Physics and the Quantum Mechanical Model
Section 5.1 Models of the Atoms
Electromagnetic spectrum
Arrangement of Electrons in Atoms
Arrangement of Electrons in Atoms
Ch. 13 Electrons in Atoms Ch Models of the Atom
Properties of Light.
Electron Configuration
Chapter 4 Arrangement of Electrons in Atoms
Chapter 5: Electrons in Atoms
Presentation transcript:

Electrons in Atoms

Evolution of Atomic Models For about 50 years after Dalton, the atom was considered a solid indivisible mass JJ Thomson proposed the plum-pudding model

Evolution of Atomic Mdels Rutherford proposed the nuclear atom, with a dense nucleus Niels Bohr propsed that electrons move in orbits around the nucleus

Evolution of Atomic Models Bohr proposed that electrons have a fixed energy The energy level of an electron is the region where the electron is likely moving Energy levels are like stairs. To move to the next stair you have to move the correct amount, or you won’t move

Evolution of Atomic Models A quantum of energy is the amount of energy required to move an electron to the next higher energy level In general, the higher the energy level of the electron, the farther it is from the nucleus

Quantum Mechanical Model Schrodinger’s equation describes the location and energy of electrons  quantum mechancial model Estimates the probability of finding an electron in a certain position

Quantum Mechanical Model In this model, the probability of finding an electron is represented by a fuzzy cloud The cloud is more dense where the probability of finding electrons is high and less dense where the probability of finding electrons is low

Atomic Orbitals The Q-M Model designates energy levels with principal quantum numbers (n) They are assigned in order of increasing energy (greater distance from nucleus) n – 1, 2, 3, 4, …..

Atomic Orbitals Within each energy level, there are sublevels The number of energy sublevels is the same as the principal quantum number Describes the SHAPE of the orbital s, p, d, f

Atomic Orbitals Within each sublevel, there are regions where electrons are likely to be found, called atomic orbitals Atomic orbitals are denoted by letters s is spherical in shape, p is dumbbell-shaped, d is cloverleaf-shaped, and f is a complex shape pg 103 in book

Atomic Orbitals The numbers and kinds of atomic orbitals depend on the energy sublevel n = 1: 1 sublevel – 1s (1 orbital, s) n = 2: 2 sublevels – 2s, 2p (4 orbitals, s and 3 p) n = 3: 3 sublevels – 3s, 3p, 3d (9 orbitals, s, 3 p, and 5 d) n = 4: 4 sublevels – 4s, 4p, 4d, 4f (16 orbitals, s, 3 p, 5 d, and 7 f)

Atomic Orbitals There are a maximum of two electrons per orbital Each sublevel also has a maximum number of orbitals Sublevel Max # of orbitals Max # of electrons s 1 2 p 3 6 d 5 10 f 7 14

Atomic Orbitals Because of the maximum allowed electrons per orbital, and the maximum orbitals per type of orbitals, it can be determined how many electrons are allowed in each energy level Energy level n 1 2 3 4 Max # of electrons 2 (s) 6 (s,p) 18 (s, p, d) 32 (s,p,d,f)

Development of the New Atomic Model

Light and Atomic Spectra Isaac Newton proposed that light was made of particles By 1900, most scientists had accepted that light was a wave

Light and Atomic Spectra According to the wave model, light consists of electromagnetic waves Electromagnetic radiation includes radio waves, microwaves, infrared waves, visible light, ultraviolet waves, x-rays, and gamma rays

Light and Atomic Spectra Four properties for measuring waves: Amplitude – wave’s height from the origin to the crest Wavelength (λ) – distance between crests

Light and Atomic Spectra Frequency (ν) – the number of wave cycles to pass a given point per unit time The units of frequency are cycles per second. The SI unit is the Hertz (Hz) which can also be expressed as s-1 Speed (c) – the rate at which the wave travels

What do you think the relationship is between speed (c), frequency (ν), wavelength (λ)?

Light and Atomic Spectra There is a relationship between the speed, frequency, and wavelength of light c = λν c is constant that equals 3.0 x 108 m/s

Light and Atomic Spectra When light passes through a prism, it produces a spectrum of colors. ROYGBIV (red-orange-yellow-green-blue-indigo-violet) is the range of visible light (380 nm – 700 nm)

Light and Atomic Spectra Every element emits light when it is excited by the passage of an electric discharge through its gas or favor Passing this light through a prism results in the atomic emission spectrum of the element

Quantum Concept Classical physics does not explain the line spectra of the elements Max Planck attempted to describe why iron changes color as it is heated

Quantum Concept Planck showed that the amount of radiant energy (E) absorbed or emitted is proportional to the frequency of the radiation. E = hν (Planck’s constant, h = 6.626 x 10-34 Js)

Quantum Concept The energy absorbed or emitted is a quantum Quanta are so small, that you are unaware that energy is quantized

Photoelectric Effect Albert Einstein proposed that light could be described as quanta of energy that behave like particles, called photons This led to the theory of the dual nature of light

Photoelectric Effect In the photoelectric effect metals eject electrons when light shines on them It depends on the frequency of the light , contrary to the ideas of classical physics

Atomic Spectra Bohr’s application of quantum theory to electron energy levels in atoms resulted in an explanation of the hydrogen spectrum

Atomic Spectra When an electron is in the lowest energy level it is in the ground state When an electron is excited, it raised to higher energy level. As it comes back to ground state, energy is emitted in the form of light

Quantum Mechanics Louis de Broglie proposed that matter could also have a dual nature λ = (h/mν) (de Broglie’s equation) Objects with measurable wavelengths cannot be seen by the unaided eye

Quantum Mechanics Werner Heisenberg stated that it is impossible to know exactly both velocity and the position of a particle at the same time (Heisenberg Uncertainty Principle)

Electron Configurations In atoms, electrons and the nucleus interact to make the most stable arrangement possible. The ways in which electrons are arranged around the nucleus are called electron configurations.

Electron Configurations Three rules tell you how to find electron configurations: Aufbau Principle – Electrons enter orbitals of lowest energy first. (see diagram on page 367 of your book)

Electron Configurations Pauli Exclusion Principle – An atomic orbital may have a maximum of two electrons. These electrons must have opposite spins (paired)

Electron Configurations Hund’s Rule – When electrons occupy orbitals of equal energy, one electron enters each orbital until all the orbitals contain one electron with parallel spins

Electron Configurations Electron configurations are written in the following way: Carbon (6 electrons) – 1s22s22p2 1, 2 = energy level s, p = sublevel Superscript 2 = number of electrons in the sublevel ** Note that the sum of the supersrcipts equals the number of electrons in the atom

Electron Configurations Electron configurations can also be abbreviated by substituting for the electron configuration of the previous noble gas: Carbon – 1s22s22p2 Abbreviated – [He]2s22p2 1s2 is the electron configuration for He, so the symbol He replaced its electron configuration

Electron Configurations There are some exceptions to the rules, such as copper and chromium