Download 10 Modern Atomic Theory and the Periodic Table Chapter Outline

Slide 1 ___________________________________ 10 Modern Atomic Theory and the Periodic Table
___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ The amazing colors of fireworks result from electron transfer
between energy levels of atoms.
Foundations of College Chemistry, 14th Ed.
___________________________________ Morris Hein and Susan Arena
Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide ___________________________________ Chapter Outline
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___________________________________ 10.1 Electromagnetic Radiation
10.2 The Bohr Atom
10.3 Energy Levels of Electrons
10.4 Atomic Structure of the First 18 Elements
10.5 Electron Structures and the Periodic Table
___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 3 ___________________________________ Electromagnetic Radiation
___________________________________ Electromagnetic Radiation:
A form of energy that runs a continuum from radio to
X-rays, visible light to microwaves.
___________________________________ Each form of radiation shares common characteristics:
they display wavelike properties and
travel at the same speed.
___________________________________ Basic Properties of Waves
Wavelength (λ): the distance between consecutive peaks
(or troughs) of a wave.
___________________________________ ___________________________________ Frequency ( ): the number of times a wave passes
through a certain point per second.
Speed: how fast a wave moves through space.
© 2014 John Wiley & Sons, Inc. All rights reserved.
___________________________________ Slide 4 ___________________________________ Electromagnetic Radiation
___________________________________ Basic Properties of Waves
___________________________________ Wavelength (λ): the distance between consecutive peaks
(or troughs) of a wave.
___________________________________ ___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 5 ___________________________________ Electromagnetic Radiation
___________________________________ Electromagnetic Spectrum:
The full range of electromagnetic radiation,
arranged based on wavelength.
___________________________________ ___________________________________ ___________________________________ Electromagnetic radiation has both wave-like
and particle properties.
___________________________________ Radiation can behave like tiny packets (“particles”)
of energy called photons.
___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 6 ___________________________________ The Bohr Atom
At high temperatures or when high voltages are applied,
elements radiate (emit) colored light.
___________________________________ When this light is passed through a prism,
a set of brightly colored lines result.
___________________________________ ___________________________________ Line spectrum of hydrogen
___________________________________ These line spectra indicate the light emitted has only
specific wavelengths/frequencies.
___________________________________ Each element possesses a characteristic
and unique line spectrum.
___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 7 ___________________________________ The Bohr Atom
___________________________________ How can these experimental results be explained?
From his study of the line spectrum of hydrogen,
Bohr proposed a revised theory of the atom.
___________________________________ ___________________________________ Bohr suggested electrons exist in
specific regions at defined
distances from the nucleus.
___________________________________ The electrons then move about
the nucleus in circular orbits at a
fixed distance from the nucleus.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 8 ___________________________________ ___________________________________ ___________________________________ The Bohr Atom
___________________________________ Bohr also suggested energy absorbed or emitted
by an atom is quantized (has discrete fixed units).
___________________________________ Bohr proposed that electrons can orbit
the nucleus at different distances.
Each orbit is a distinct, discrete (quantized) energy level.
___________________________________ When an atom absorbs energy,
the electrons can be promoted to
higher energy levels.
When an atom emits energy,
the electrons can decays to
a lower energy level.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 9 ___________________________________ ___________________________________ ___________________________________ ___________________________________ The Bohr Atom
___________________________________ Ground state: lowest energy level for an atom.
___________________________________ Each line in the spectrum corresponds to emission
of energy as an electron relaxes from a
higher to lower energy level.
___________________________________ Color of light emitted depends on the gap
between the energy levels.
___________________________________ Bohr’s theory worked very well to explain and predict
the line spectrum of hydrogen…. BUT….
___________________________________ Bohr’s theory broke down in multi-electron systems.
___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 10 ___________________________________ The Dual Particle/Wave Nature of Matter
In 1924, DeBroglie (a French chemist) proposed matter
could be treated as either a wave or a particle.
___________________________________ For large objects, the wave properties are negligible
due to their very small wavelengths.
___________________________________ ___________________________________ For smaller objects with less mass, i.e. an electron,
the wavelike properties of matter become very important.
___________________________________ Schrödinger in 1926 expanded the wavelike properties
of matter by developing an equation to describe
electrons as waves.
___________________________________ This theory, called quantum mechanics, allows one to
calculate the probability of finding an electron in space.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 11 ___________________________________ ___________________________________ The Dual Particle/Wave Nature of Matter
___________________________________ Quantum mechanics deal in electron probabilities;
orbits from Bohr theory are replaced by orbitals.
___________________________________ Orbitals: regions of space with a high probability of
finding an electron.
___________________________________ ___________________________________ ___________________________________ ___________________________________ An orbital for a hydrogen atom.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 12 ___________________________________ Energy Levels of Electrons
___________________________________ Bohr’s idea of quantized energy levels does have
parallels in quantum mechanics.
___________________________________ For example, quantum mechanics predicts discrete,
quantized principal energy levels for electrons in an atom.
___________________________________ Principal energy level (n):
provides a general idea of the distance
of an electron from the nucleus
(as n increases, so does the distance
from the nucleus)
___________________________________ ___________________________________ ___________________________________ n can be a positive integer (1,2,3, etc.)
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 13 ___________________________________ Energy Levels of Electrons
___________________________________ Each energy level can be divided into sublevels.
Each sublevel corresponds to a different type
of orbital that can house electrons.
___________________________________ Principal quantum level n =1
___________________________________ Contains only one sublevel/orbital (1s orbital)
___________________________________ The orbital is spherical in nature,
as are all s orbitals.
___________________________________ The orbital is a space where an electron has a
90% probability of being located.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 14 ___________________________________ ___________________________________ Energy Levels of Electrons
___________________________________ How many electrons can fit in an orbital?
___________________________________ Pauli Exclusion Principle: an atomic orbital can hold two
electrons, which must have opposite spins.
___________________________________ Electron spin is represented by arrows (  or  )
___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 15 ___________________________________ Energy Levels of Electrons
Principal quantum level n =2
Contains two sublevels/orbitals (2s and 2p orbitals)
___________________________________ The 2s orbital is spherical like a 1s orbital,
but larger and higher in energy.
The 2p sublevel consists of three orbitals: px, py and pz.
The shape of the 3 orbitals is the same;
they differ in their orientation in space.
___________________________________ ___________________________________ ___________________________________ ___________________________________ 6 total electrons can occupy the 3 p orbitals of a subshell.
Each p orbital has two lobes.
© 2014 John Wiley & Sons, Inc. All rights reserved.
___________________________________ Slide ___________________________________ Energy Levels of Electrons
16 ___________________________________ Principal quantum level n =3
Contains three sublevels/orbitals (3s, 3p and 3d orbitals)
___________________________________ The 5 3d orbitals have unique shapes relative
to s and p orbitals.
___________________________________ ___________________________________ ___________________________________ 10 total electrons can occupy the
5 d orbitals of a subshell.
___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide ___________________________________ Energy Levels of Electrons
17 With each new principal quantum level,
a new sublevel/orbital type is introduced.
___________________________________ Quantum Level Summary
___________________________________ Sublevels
Principal Quantum
Level (n)
1
1s
_____
_____
_____
2
2s
2p 2p 2p
_____
_____
3
3s
3p 3p 3p
3d 3d 3d 3d 3d
_____
4
4s
4p 4p 4p
4d 4d 4d 4d 4d
4f 4f 4f 4f 4f 4f 4f
___________________________________ ___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 18 ___________________________________ Energy Levels of Electrons Practice
___________________________________ What is the maximum number of electrons
in a 4d sublevel?
___________________________________ ___________________________________ a. 2
b. 4
c. 6
Any d sublevel has 5 total orbitals.
Two electrons can be housed in each orbital.
___________________________________ d. 10
___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 19 ___________________________________ Energy Levels of Electrons Practice
___________________________________ What is the maximum number of electrons that can
occupy the n = 3 sublevel?
a. 8
b. 2
c. 18
d. 10
___________________________________ ___________________________________ The n = 3 sublevel has 3 types of orbitals:
s (1), p (3), and d (5).
___________________________________ Two electrons can occupy each orbital.
(9 x 2 = 18)
___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 20 ___________________________________ Atomic Structure of the First 18 Elements
___________________________________ Hydrogen: consists of a nucleus with one proton
and one electron in a 1s orbital.
How are electrons treated in more complicated atoms
that contain multiple electrons?
Assuming multielectron atoms have orbitals
similar to that of the hydrogen atom,
rules for filling electrons can be developed.
Guidelines for filling electrons:
___________________________________ ___________________________________ ___________________________________ 1. Only up to two electrons can occupy an orbital.
2. Electron will occupy lower energy orbitals first. Orbital
energies: s < p < d < f for a given n value.
3. Each orbital in a sublevel must contain an electron before
another electron can be added to any of the orbitals.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 21 ___________________________________ ___________________________________ ___________________________________ Atomic Structure of the First 18 Elements
Three ways of depicting atomic and electronic structure:
I) Atomic Structure Diagrams
___________________________________ Depict both the nuclear and electronic structure
___________________________________ ___________________________________ II) Electron configuration
___________________________________ Each orbital is listed, in order of increasing energy,
while depicting the number of electrons in
each orbital/sublevel.
___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 22 ___________________________________ Atomic Structure of the First 18 Elements
___________________________________ Three ways of depicting atomic and electronic structure:
___________________________________ III) Orbital Diagram
Boxes represent orbitals and electron spins
are represented as arrows.
___________________________________ ___________________________________ ___________________________________ 3p
___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 23 ___________________________________ Atomic Structure of the First 18 Elements
___________________________________ Helium
Hydrogen
___________________________________ 1s1
1s
Orbital Diagram
Electron
configuration
1s2
1s
Orbital Diagram
Lithium
___________________________________ Berylium
2s
1s
___________________________________ 2s
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 24 ___________________________________ 1s22s2
1s22s1
1s
___________________________________ Electron
configuration
___________________________________ Atomic Structure of the First 18 Elements
___________________________________ Filling the p subshell
Boron
___________________________________ 1s22s22p1
1s
2s
___________________________________ 2p
Carbon
___________________________________ 1s22s22p2
___________________________________ 1s
2s
2p
Note the electrons are in different orbitals per Rule 3.
The similar spin will be discussed shortly.
© 2014 John Wiley & Sons, Inc. All rights reserved.
___________________________________ Slide 25 ___________________________________ Atomic Structure of the First 18 Elements
___________________________________ Filling the p subshell
Nitrogen
___________________________________ 1s22s22p3
1s
2s
___________________________________ 2p
Note the electrons are in different orbitals per Rule 3.
___________________________________ Oxygen
___________________________________ 1s22s22p4
1s
2s
2p
___________________________________ Two electrons must be paired in one p orbital.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 26 ___________________________________ Atomic Structure of the First 18 Elements
___________________________________ Filling the p subshell
Fluorine
___________________________________ 1s22s22p5
1s
2s
___________________________________ 2p
Neon
___________________________________ 1s22s22p6
1s
2s
___________________________________ 2p
___________________________________ All electrons are paired in the p shell.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 27 ___________________________________ Atomic Structure of the First 18 Elements
___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 28 ___________________________________ Atomic Structure of the First 18 Elements
___________________________________ Beyond Ne
Sodium
___________________________________ 1s22s22p63s1
1s
2s
2p
3s
___________________________________ Begin filling the 3n shell.
___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 29 ___________________________________ Atomic Structure of the First 18 Elements
___________________________________ Valence Electrons:
electrons located in the highest energy
(outermost) orbitals of an atom.
Example
Oxygen
Electron configuration
1s22s22p4
___________________________________ ___________________________________ Outermost valence electrons are in the n =2 subshell;
oxygen has 6 total valence electrons.
___________________________________ The column number (1A-7A) in the periodic table
gives the valence electrons of an element.
___________________________________ Valence electrons participate in bonding to form
molecular compounds (see Chapter 11).
___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide ___________________________________ Electronic Configuration Practice
30 ___________________________________ How many valence electrons does phosphorus contain?
___________________________________ P is in Group 5A.
It will contain 5 valence electrons.
___________________________________ c. 15
Electron Configuration
1s22s22p63s23p3
___________________________________ d. 18
Valence electrons
___________________________________ a. 5
b. 8
___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 31 ___________________________________ Electronic Configuration Practice
___________________________________ Which element could have the following
electron configuration?
___________________________________ 1s22s22p63s23p6
___________________________________ a. Cl
The element contains 18 electrons.
It must also contain 18 protons.
Atomic number 18 = argon.
b. Ca
c. Ar
d. S
___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 32 Electron Structures and the
Periodic Table
___________________________________ How does the electronic structure of atoms relate to their
positioning on the periodic table?
___________________________________ ___________________________________ ___________________________________ Origins of the Periodic Table
___________________________________ Mendeleev and Meyer proposed organizing elements
based on increasing atomic masses.
Their ideas formed the origins of the modern periodic table.
___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 33 ___________________________________ The Modern Periodic Table
___________________________________ columns (groups/families):
___________________________________ elements with similar properties.
___________________________________ rows
(periods):
___________________________________ increasing Z
___________________________________ (atomic number)
___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 34 ___________________________________ The Modern Periodic Table
___________________________________ ___________________________________ Period number corresponds to the highest
principal quantum number n of the elements.
___________________________________ Group numbering: by numbers 1–18 or
with numbers/letters (i.e., 7A).
___________________________________ A groups are the representative elements.
___________________________________ B groups are the transition elements.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 35 ___________________________________ ___________________________________ The Modern Periodic Table
Main Group
Alkali Metals
Alkaline Earths
___________________________________ Noble Gases
Halogens
___________________________________ Transition Metals
___________________________________ ___________________________________ ___________________________________ ___________________________________ Main Group
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 36 ___________________________________ Periodic Table Practice
___________________________________ Magnesium is a member of what group of elements?
___________________________________ a. Halogens
___________________________________ b. Noble gases
c. Alkali metals
___________________________________ d. Alkaline earth metals
___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 37 ___________________________________ The Modern Periodic Table
___________________________________ Group Commonalities: All elements in a group
have similar valence electron configurations.
This often leads to similar reactivity
of elements in a group.
Because electron configurations of larger elements are
very long, a shorthand notation is used that
highlights valence electrons.
Example
Na
___________________________________ ___________________________________ ___________________________________ [Ne]3s1
This indicates the electron configuration of sodium
is that for Ne with an additional 3s1 electron.
The shorthand electron configuration always uses the
previous noble gas core with the valence electrons
for the element of interest.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide ___________________________________ ___________________________________ Initially, one may expect to fill 3d electrons
before 4s electrons.
___________________________________ However, based on reactivity of the elements K and Ca,
they resemble metals with valence electrons in s orbitals.
___________________________________ Example
K
Ca
[Ar]4s1
[Ar]4s2
___________________________________ Elements 21-30 are transition elements where
electrons now fill in the 3d subshell.
___________________________________ Once the 3d subshell is filled, the 4p shell begins to fill.
___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
39 ___________________________________ Electron Filling
38 Slide ___________________________________ ___________________________________ Electron Filling
___________________________________ Sublevel Filling Diagram
___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide ___________________________________ Electron Filling Practice
40 ___________________________________ 4s1
The electron configuration [Ar]
is the
ground state electron configuration of:
___________________________________ ___________________________________ a. K
b. P
c. Fluorine
The element contains 1 valence electron
in the fourth period (due to n = 4).
___________________________________ d. Na
___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide ___________________________________ Electron Filling Practice
41 ___________________________________ The electron configuration [Ne] 3s23p1, is the ground
state electron configuration of:
___________________________________ ___________________________________ a. Na
b. Al
c. Ar
The element contains 3 valence electrons
in the third period (due to n = 3).
___________________________________ d. S
___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 42 ___________________________________ Chemical Periodicity
___________________________________ Groups of elements show similar chemical properties
because of similarities in their valence electrons.
___________________________________ ___________________________________ ___________________________________ Group number equals the total number of
outermost valence electrons.
___________________________________ Example Group 7 – contains the
ns2np5 valence configuration
___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 43 ___________________________________ Learning Objectives
___________________________________ 10.1 Electromagnetic Radiation
___________________________________ List the 3 basic characteristics of electromagnetic radiation
___________________________________ 10.2 The Bohr Atom
Explain the relationship between the line spectrum
and the quantized energy levels of an electron in an atom.
___________________________________ 10.3 Energy Levels of Electrons
___________________________________ Describe the principal energy levels,
sublevels and orbitals of an atom.
___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 44 ___________________________________ Learning Objectives
___________________________________ 10.4 Atomic Structure of the First 18 Elements
___________________________________ Use the guidelines to write electron configurations.
___________________________________ 10.5 Electron Structures and the Periodic Table
___________________________________ Describe how the electron configurations of the atoms
relate to their position on the periodic table and
write electron configurations for elements based
on their position on the periodic table.
© 2014 John Wiley & Sons, Inc. All rights reserved.
___________________________________ ___________________________________