Atomic Structure and The Electron
SHS Chemistry
Chapters 4 & 5
LEQs
The Nuclear Atom
• How has the model of the atom evolved over time? (5.1) • What are the components of the nuclear atom? (4.1, 4.2) • How are isotopes utilized to calculate atomic mass? (4.3)
• How is carbon‐14 used to estimate the age of archeological items? (25.2)
Physics and the Electron
• How does energy relate to light? (5.3)
• How is the atomic emission spectra produced in substances? (5.3)
Electron Arrangement • How is the electron viewed in the quantum mechanical model? (5.1) • How are electron configurations derived from quantum numbers to describe atoms? (5.2) The Nuclear Atom
How has the model of the atom evolved over time? (5.1) •
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Form groups Have a model selected for you (Dalton, Thomson, Rutherford, Bohr, Electron Cloud Model)
For this exercise you will choose an atomic model and produce a Power Point with the following components.
– (Slide 1) Name of the model and persons responsible.
– (Slide 2) Experiment leading to the transition into that atomic model (discuss time period, what was going on in the world at the time, describe the players, and detail experiment) – (Slide 3) The Model (discuss components in detail and how it is different than the one before it. – (Slide 4)Two questions to ask the class about your presentation.
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You may link video etc.
10 min limit.
You have two days to submit. Present on day 3.
Do not make the slides excessively wordy! Use Diagrams.
Be sure to make note cards so you do not read from the slides!
Assessment: Presentation rubric and info found on unit test.
Evolution of the atom: follow up questions
View the class ppt.
• What are the four parts of Dalton’s atomic theory?
• What are the plums in plum puddin’?
• How was the nucleus discovered?
• What did Bohr prove about electrons?
• Why aren’t there any neutrons in the Bohr model?
• Why is the electron viewed as a “cloud” in the Electron Cloud Model.
The Nuclear Atom
What are the components of the nuclear atom?
(4.1, 4.2) Electrons outside of nucleus
The Bohr Model
Atomic number = e‐
for a neutral atom
Shell
Max # of e‐
1 (L)
2
2 (M)
8
3 (N)
18
4 (O)
36
5 (P)
54
6 (Q)
80
7 (R)
110
Protons and neutrons in nucleus Mass Number = p+ & n°
for an individual atom
How do we describe atoms?
• Atomic number = # of protons (this tells you what element it is)
• Mass number = # of protons + # of neutrons • Because atoms can exists with differing neutrons for an element, a way to refer to individual atoms uses the mass number and/or atomic number in the name and symbol. – Example: an individual atom of carbon with a mass of 12 could be written as 126C or Carbon‐12
20
Ca
40.078
This is atomic mass not mass number. If you round this off it tells you the most abundant isotope. Nuclear Atom: follow up questions
• What is in the nucleus?
• Where are the electrons?
• How do you calculate # of protons, electrons and neutrons?
• What tells identifies the element?
• Can the mass of an atom be different than the atomic mass on the periodic table?
How carbon‐14 dating work?(25.2)
Decay of caron‐14
Predictable rate…
Half‐Life = ½ of mass converted to nitrogen‐14 every 5730yrs Play the pHet Dating game.
Carbon dating: follow up questions
• What occurs in the decay of carbon‐14?
• What is half life?
• How is carbon dating used to date old stuff?
The Nuclear Atom
How are isotopes utilized to calculate atomic weight? (4.3)
The atomic weight is measured in amu or daltons.
One amu is equal to 1/12 of the mass of a carbon‐12 atom. So one proton or neutron is roughly one amu (an electron is much smaller 1/2000 amu).
If we change the unit from amu to g we call it the gram atomic mass.
For oxygen‐16 the…
Atomic mass is 16 amu
Gram atomic mass is 16 g
How does this relate to what we see on the periodic table? We will explore this through the element Beanium.
Beanium Activity
I’m anything but average!
Isotopes: follow up questions
• Why are the atomic masses on the periodic table a whole number?
• What is the difference between average and weighted average?
• When is it the same?
Physics and the Electron
How does energy relate to light? (5.3)
How is the atomic emission spectra produced in substances? (5.3)
EXPERIMENT: FLAME TEST (2 PARTS)
Plank(Energy of a Wave)
Nobel Prize in 1918 for deriving the relationship between the frequency of light emitted and energy
The Math
The Variables
Lambda (λ)= wavelength
Propagation of a Wave
Nu (ν) = frequency in s‐1
c = λν
C = velocity of light (3.00 x 108 m/s)
Energy of a Wave
‐34
h = Plank’s constant 6.626 x 10 J∙s
E = hν
E = energy (usually measured in Joules)
The Electromagnetic Spectrum
Bohr(Energy Levels)
Nobel Prize in 1922 for his description of the electron in “quantum states”.
Light and Emission Spectra: follow up questions
• How do light bulbs emit light?
• How do they create different colors in fireworks?
• Can those colors be used to identify elements in the fireworks?
• How? and Why?
Electron Arrangement How is the electron viewed in the quantum mechanical model? (5.1) Bohr model depicting the electrons as particles in orbits.
Electron Cloud model depicting the electrons as waves in orbitals.
Schrödinger: (Wave (Psi) Function)
Schrödinger's Cat: A cat, along with a flask containing a poison, is placed in a sealed box. If an internal Geiger counter detects radiation, the flask is shattered, releasing the poison that kills the cat. The Copenhagen interpretation of quantum mechanics implies that after a while, the cat is simultaneously alive and dead. Yet, when we look in the box, we see the cat either alive or dead, not a mixture of alive and dead. Erwin Schrödinger won the Nobel Prize in 1933 for his efforts in explaining dual states in quantum mechanics.
Electron Arrangement How are electron configurations derived from quantum numbers to describe atoms? (5.2) The locations of electrons are described by certain addresses determined by allowable parameters.
Quantum Numbers
Street Addresses
Electron Configurations.
Principal QN (n)
State
Energy Level (shell)
Azimuthal QN (l)
Town
Sublevel (group of clouds)
Magnetic QN (m)
Street
Orbital (cloud)
Spin QN (s)
Home Individual Electron Each cloud or orbital can hold 2 electrons. The s sublevel has 1 cloud, the p 3 clouds, the d 5 clouds and the f 7 clouds.
How many electrons can the d sublevel hold?
Sublevels and Orbitals
Electrons and the Quantum Mechanical Model: follow up questions.
• How is the quantum mechanical (electron cloud) model different than the Bohr model?
• Why are the electrons represented as clouds?
• What is meant by the term photon?
• What are Quantum Numbers?
• What are Electron Configurations?
Electron Arrangement How are electron configurations derived from quantum numbers to describe atoms? (5.2) 1. Orient a piece of paper 1s
portrait.
2s 2p
2. Fold it into four sections 3s 3p 3d
across
3. Fold it into 8 section down. 4s 4p 4d
4f
4. Fill in as directed.
5s 5p 5d
5f
5. Draw diagonals across the 6s 6p 6d
6f
corners.
7f
6. Electrons fill in from upper 7s 7p 7d
right to lower left.
8s 8p 8d
8f
Making an sublevel filling diagonal rule.
1.
2.
3.
4.
5.
6.
Orient a piece of paper portrait.
Fold it into four sections across
Fold it into 8 section down.
Fill in as directed.
Draw diagonals across the corners.
Electrons fill in from upper right to lower left.
Rules for filling sublevels.
• Aufbau Principle: Electrons fill orbitals starting at the lowest available (possible) energy states before filling higher states • Pauli Exclusion Principle: For electrons in a single atom, it states that two electrons can have the same exact location but different spins.
• Hund's rule: Every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied, and all electrons in singly occupied orbitals have the same spin.
Electron Configurations: follow up questions
• Why do some atoms have more than one shell partially filled with electrons?
• What is common with noble gas electron configurations?
• Write the electron configuration of N.
• Write the electron configuration of Al.
• Write the electron configuration of Fe.
What should I know from this?!
Know!
•Definitions for all the vocab
words found on the learning
map.
•Correct usage of measuring
devices
•All conversion factors related
to a mole
•The names and components
of the various atomic models
presented in the unit.
•The experiments that derived
the various atomic models
presented in this unit.
•The sublevels associated with
the electrons.
Understand!
•All models are appropriate for
certain situations.
•All atoms are isotopes!
•The locations of the electrons are
associated with an amount of
energy.
•Electrons have both particle and
wave like properties.
•Electrons can be located in
certain allowable locations that are
described with “addresses”.
•Light is the product of the
excitation of electrons.
•The mass listed on the periodic
table is the weighted average of the
isotopes of the element.
Do!
•Draw a Bohr atom of technetium,
label all protons, neutrons and
electrons (placed in the correct
shells).
•Write two complete electron
configurations. One for an element
that begins with the same letter as
your first name and a different one
that begins with the same letter as
your last name. (if either is “J” use
Kr)
•Chapter 4, #s 59, 65, 69, 81
•Chapter 5, #s 51, 55*, 57, 71, 73