Transcript Unit 3: Atomic Theory and Atomic Structure PowerPoint

HONORS CHEMISTRY
September 9, 2013
Atomic History

Democritus
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
Dalton


JJ Thomson
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Rutherford

Chadwick

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Bohr


Matter is composed of empty
space in which atoms move
Elements consist of atoms and
compounds are collection of
atoms
“Plum pudding model” : Atoms
contain negative particles called
electrons
Alpha particles, positive charge
with a mass 7500x of electron.
Proved the plum pudding model
was wrong. Nucleus center ( +)
and tiny electrons moved in space
around it.
Discovered neutrons (slightly
more massive than a proton).
Electrons are in circular paths
depending on their energy levels
Atomic History

De Broglie
Schrodinger

Millikan


Moseley




electrons move in waves rather
than straight circular paths
Wave Mechanical Model or
Quantum Mechanical Model.
Furthered De Broglie’s idea of
waves by stating that electrons
are in clouds but in certain energy
region
Oil drop experiment: discovered
that atoms had positive and
negative charges and that they
equal each other
Helped to arrange atoms in the
periodic table. Atoms were
arranged in increasing atomic
number using wavelengths and
x-rays
Atoms, Isotopes and Ions
How do atoms of different
elements differ?
The Modern View of Atomic
Structure
What are the particles that make up an
atom and how do they differ from one
another?
02m14an1
 proton
mass = 1 amu charge = +1
 neutron
mass = 1 amu charge = 0
 electron
mass = “0” amu charge = -1
 1 amu = 1.6726 x 10-27 kg
1/1840
atoms have equal numbers of protons
and electrons so they are electrically
neutral

Atomic Number

Atomic number
Number of protons in an atom
 Identifies the element

6
C
Carbon
12.01115
Atomic Number

Use the Periodic Table to complete the
following.
1. What element has the atomic number 18?
2. What element has 35 protons?
How are atoms of one element
different from those of another
element?

They have different numbers of these
subatomic particles.
Atomic Number
Chemical Symbol
Element Name
Average Atomic Mass
1
H
Hydrogen
1.00797
Isotopes
How do we distinguish between atoms?
 Do all atoms of an element have the same
composition?
Heavy Water and Water Ice Cube in
water

Isotopes

What implication does this have for the masses
of atoms?





Average atomic mass
Isotopes differ only in the number of Neutrons
Difference is shown by their mass numbers
Notation: superscript for mass number, which is
the sum of the number of protons and neutrons
Notation: subscript for atomic number, which is
the number of protons (or electrons)
7 Li
3
9 Be
4
11 B
5
Nuclear Particles

How many of each particle (protons, neutrons
and electrons) are in these atoms?
76
35 Br
14
78
15
7N
18 O
8
17 O
8
80
35Br
35Br
7N
16 O
8
15 O
8
Ions

When an atom loses or gains electrons
and acquires a net electrical charge.
Gain electrons – negative ion - anion
 Lose electrons – positive ion - cation

Mg
Mg2+
Ions
Charge of ion = # of protons - # of electrons
How many protons, neutrons and electrons
does 4120Ca2+ have?
How many protons, neutrons and electrons
does 7835Br - have?
Think-Pair-Share

Atomic Structure Worksheet
Closure
1. How many protons, neutron and electrons
does Mg have?
2. How many protons, neutron and electrons
does 74Be -2 have?
HONORS CHEMISTRY
September 10, 2013
Brain Teaser
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Place homework on your desk
How many protons, neutrons and electrons
does 3211Na +1 have?
Who developed the planetary model of the
atom based on quantum energy levels
Who discovered that most of the atom’s
mass is located in the nucleus of an atom
and the atom is mostly empty space
Who discovered the electrons and
developed the plum pudding model of the
atom
Agenda
Brain Teaser
 Grade Homework: Atomic Structure Worksheet
 Notes:

Wave and Particle Nature of Light
 Line Spectra
 Quantum Theory
 Bohr Models


Homework

Bohr’s Model Worksheet/Isotope Worksheet
Review (Insert)
Mass of Proton: 1.67 x 10-24 grams = 1 amu
 Mass of Neutron: 1.67 x 10-24 grams = 1 amu
 Mass of Electron: 9.1 x 10-28 grams
(essentially zero)

Unit 3
Light and Quantized Energy
Electron Configuration

Objective:

Learn how electrons are arranged in an atom and
how that arrangement plays a role in their chemical
behavior
How do we know what makes
up an atom?
The Atom is a Scientific Model
With the scanning tunneling microscope
we can see atoms, but we still cannot see
their internal structure.
 Scientific models are created by
experiments, but are often modified.
 There may be flaws in the current model.

What do atoms look like?


See the electron microscope image of the
molecular art drawn with gold (Au) atoms.
See the image of graphite. Are these images
proof of atoms? How do we see atoms?
nickel
benzene
graphite
How do we know what
makes up atoms?
Cathode Ray Tubes

Why does the beam bend?
Gold Foil Experiment

Examine the diagram of Rutherford’s alpha ray
experiment. What is the implication of this
experiment?
Line Spectra
700

650
600
550
500
450
400
350
Bright Line Spectra
 Lines of color produced by light emitted from
heating substances and passing them through a
prism
 Fingerprints of elements
 Researchers can determine values of energy
levels in atoms
 Used to identify different elements
Observation of unique line
spectra led to Quantum Theory
E=hν
Fourth
Third
Second
First
Nucleus

Demo
Point Spectroscope towards the fluorescent
light bulb
 Observe the bright line spectrum of mercury
and phosphorous

Where all of this has led to

Bohr Model – did some good things but it
is not the whole truth.
Some Questions

Color arises from electrons shifting from one
orbital to another of different energy

Ground state and excited state

What shift would give rise to emission of light?
to absorption of light?
Where all of this has lead to

Quantum Model
What is the Quantum Mechanical
Model?

It predicts quantized energy levels for
electrons, like the Bohr model.
What is Quantum Theory?

It does not describe the exact path that
electrons take around the nucleus of an
atom, but is concerned with the probability
of an electron being in a certain place.
Nucleus
Orbitals
Areas where an electron can be found
 Can have up to two electrons
 Fuzzy boundaries  “Electron Cloud”

The Closed Sphere Model
For convenience
 Shows where the electron is 90% of the
time

The Heisenberg Uncertainty
Principle
You can never know exactly where an
electron is if you know exactly how fast it
is moving.
 You can never know exactly how fast an
electron is moving if you know exactly
where it is.

Bohr Diagram
Practice Worksheet
THE END
HONORS CHEMISTRY
September 12, 2012
Brain Teaser
Place Homework on your desk
 Write the complete symbol from the given
information below:

20 protons, 22 neutrons, 18 electrons
 15 protons, 17 neutrons, 18 electrons
 17 protons, 18 neutrons, 17 electrons


How many protons, neutrons, and
electrons are there for each of the following
atoms or ions?
 12
B+3
 80 35 Br
Agenda
Brain Teaser
 Grade Homework
 Bright Line-Emission Spectra
 Practice Quiz
 Homework


Study for Quiz (Friday)
Grade Homework

Bohr Diagram Worksheet
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Look for patterns:
 Period
 Group
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Label Periodic Table
Isotopes Worksheet
Bright Line Emission Spectra
Lab Activity

Objective

Identify different metals through flame tests and using
bright line emission spectra
Background
Light = Electromagnetic radiation
 Frequency of light relates to energy (Diagram)

Higher Frequency = Higher Energy
 Frequency and Color are related
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(Low)Radio, M, IR, Visible, UV, X-Ray, Gamma Ray(High)
Visible Light: (Lower) R O Y G B I V (Higher)
 White light has all the colors


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Prism/Diffraction Gratin  Breaks up colors
Gaseous element contained in a tube 
energize it with electricity  glow/gives off
visible light
Background
Electrons absorbing energy “excited”
 Electrons giving off energy  Gives off light
 All atoms have all energy levels but they may
not have e- on them. (Diagram)

e- jumps to a higher energy level “excited” state
 e- will give off energy/falls back down  give off
visible light (lowest possible energy level = ground
state)
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 Energy
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of photon is proportional to the color
Some energy are given off as invisible spectrum like IR or UV
Red photon is lower in energy compared to blue photon
Background
Tube filled with Ne, H, or He (discrete lines) 
Atomic Emission Spectra
 e- cannot have any amount of energy but only
certain amount of energy (no in b/w color)
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Evidence: only certain colors are given off.
e- exist only at certain distances from the nucleus
Every element has a unique emission spectrum
because it has different electron configuration

Emission Spectra as a fingerprint of elements
 Applications:
Astrophysics or Forensics
Background
Electrons are only allowed in certain
energy levels, only have a certain amount
of energy, can only give off a certain
amount of energy (quantized energy)
 Different elements have different
frequencies and they give off a different
set of colors

Line Spectra
700
650
600
550
500
450
400
350
Observation of unique line
spectra led to Quantum Theory
E=hν
Fourth
Third
Second
First
Nucleus
Element Finger Print
07m07an1
Spectroscopes
Practice using the Spectroscopes
 What do you see?
 Where is it coming from?

Lab
Line Spectrum Station Rotation
At each Station
Spectra
 Observe through
spectroscope
 Record measurements
and notes
 Switch roles to judge
precision of
observation
Data Analysis
 Compare spectra to
various reference
sources
 Identify substance
 Work on study
questions
Lab Rotation

Identify the emission spectra for 5 gas
tubes and 4 stations for Flame tests

Flame test: Dip the sticks in water and WEAR
GOGGLES!
Use colored pencils to mark the reference
for each station (Gas Tubes)
 Use colored pencils to mark the reference
for Flame Tests
 Write a qualitative analysis on each
emission spectrum

Questions?
Color Coding the Periodic Table
Activity
Read handout
 Fill out Family Ties (Student Worksheet)
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Homework:

Study for Quiz (Friday)
Start
Lab
Line Spectrum Station Rotation
At each Station
Pair A
Spectra
 Observe through
spectroscope
 Record measurements
and notes
 Switch roles to judge
precision of
observation
Pair B
Data Analysis
 Compare spectra to
various reference
sources
 Identify substance
 Work on study
questions
Spectroscopes
What do you see?
 Where is it coming from?

Line Spectra
700
650
600
550
500
450
400
350
HONORS CHEMISTRY
September 17, 2012
Brain Teaser

Explain why each element can produce its
own bright line spectrum
700
650
600
550
500
450
400
350
Agenda
Brain Teaser
 Pre-Test: Periodic Trends
 Notes:

Bohr’s Model
 Orbital Diagrams and Electron Configuration

Practice Writing electron configuration
 Homework


Electron configuration worksheet
Bohr's Model
Model of
electrons
in fixed
orbits to
explain
quantization
 Transitions
between
orbits
emits or
absorbs
light 07m07an1
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Figure 6.14
Observation of unique line
spectra led to Quantum Theory
E=hν
Fourth
Third
Second
First
Nucleus
Orbital Diagrams and Electron
Configurations
n = Principle quantum number
 Describes the energy level the electron occupies

n=4
n=3
n=2
n=1
Orbital Energy Levels
Shape of orbital
designated by the
letters

s, p, d, f, g
Excited states
Ground state
Shapes of Orbitals


Shape of orbital designated by the letters
s, p, d, f, g
Orbitals have
different shapes
s Orbital shape
The s orbital has a
spherical shape
centered around
the origin of the
three axes in space.
p orbital shape
There are three dumbbell-shaped p orbitals
in each energy level above n = 1, each
assigned to its own axis (x, y and z) in space.
d orbital shapes
Things get a bit more
complicated with the five
d orbitals that are found
in the d sublevels
beginning with n = 3. To
remember the shapes,
think of “double dumbells”
…and a “dumbell
with a donut”!
Shape of f orbitals
Combination
of electron
microscopy
and x-ray
diffraction
produced
image of
orbitals
Sets of Orbitals (Subshells)


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

Depending on the type of orbital, we find that they
occur in sets differing in their orientation in
space
s - set of 1
p - set of 3
d - set of 5
f - set of 7
Sizes of orbitals

Size depends on the value of n

Orbitals with the same n are about the
same size
Check for understanding
What is the principal quantum number for
Ar?
 What are the subshells?
 How many sets of electrons are found in
each subshell?

Electron Configurations of
Some Atoms

The
first
ten
elements
1s1
1s2
1s2 2s1
1s2 2s2
1s2 2s2 2p1
1s2 2s2 2p2
1s2 2s2 2p3
1s2 2s2 2p4
1s2 2s2 2p5
1s2 2s2 2p6
Shorthand Notation for Orbitals
Combinations of first two quantum
numbers; number of orbital types equals
the shell number (n).
 1s
 2s, 2p
 3s, 3p, 3d
 4s, 4p, 4d, 4f
 5s, 5p, 5d, 5f, (5g)
 6s, 6p, 6d, 6f, (6g, 6h)
(Stop: Period 5)

HONORS CHEMISTRY
September 18, 2012
Brain Teaser
Place Homework on your desk
 Write the Electron Configuration for the
following elements:

Si
 Co
 Se

Agenda
Brain Teaser
 Grade Worksheet
 Review


Writing Electron Configuration
Notes: Orbital Diagram
 Homework

Short Hand Electron Configuration
 Orbital Diagram

Grade Homework

Refer to Worksheet (Arrangement of
Electrons I)
Check for understanding (P6)
What is the principal quantum number for
Ar?
 What are the subshells?
 How many sets of electrons are found in
each subshell?

Aufbau Principle

Aufbau Principle: start with the nucleus and
empty orbitals, then “build” up the electron
configuration using orbitals of increasing
energy
Electron Configurations
 Electron
Spin and Pauli Exclusion
Principle:
 Only two electrons can occupy a
single orbital and they must have
opposite spins
Electron Configurations
 Hund's
Rule:
 When filling a subshell, such as the
set of 3 p orbitals, place 1 electron
in each before pairing up electrons
in a single orbital
Electron Configurations
Arrangement of electrons in the orbitals is
called the electron configuration of the
atom
 The ground state configuration can be
predicted, using the Aufbau Principle, the
Pauli Exclusion Principle, and Hund’s
Rule.

Electron configurations
Filling _ rules.exe
How do we know what the filling
order is?

What chemistry tool might we rely on?
Electron Configurations and
the Periodic Table

Valence electron configurations repeat
down a group
Ground state electron
configurations

Example: Li
atomic number = 3
 nucleus has 3 protons
 neutral atom has 3 electrons

2
electrons in 1s orbital, 1 electron in 2s orbital
2s
1s
Different ways to show electron
configuration
Energy level diagram
Box notation

1s
2s

2s
1s
Spectroscopic notation
Li 1s2 2s1
Read this “one s two”
not “one s squared”
Write the superscript 1.
Don’t leave it blank
Practice

Review (on separate sheet of paper)
Electron Configuration
 Orbital Diagram


Electron configuration worksheet
Using the Periodic Table
The last subshell in the electron configuration is one of
these
(row #) s
(row # – 1) d
(row #) p
(row # – 2) f
The f-block is inserted into to
the d-block
Electron configuration of O

Atomic number of O = 8 so neutral atom has 8 e–
Electron configuration of Co

Atomic number of Co = 27 so neutral atom has 27 e–
Simplifying electron
configurations

Build on the atom’s noble gas core
1s2

He
O 1s22s22p4
O [He]2s22p4

Ar 1s22s22p63s23p6
Co 1s22s22p63s23p64s23d7
Co [Ar]4s23d7

1s

2s
  
2p
             
1s 2s
2p
3s
3p
4s
3d

Noble Gases
Far right of the periodic table
 These elements are extremely unreactive
or inert
 They rarely form compounds with other
elements

Noble Gas electron configurations

What is the electron configurations for
Neon

Abbreviated way to write configurations

Start with full outer shell then add on
Br
 Ba

Noble Gases
 Neon-
emits brilliant light when stimulated by
electricity – neon signs- 4th most abundant element
in the universe.
 Helium- light non reactive gas- used balloonsinexpensive, plentiful and harmless
 Radon- radioactive gas- can cause cancercolorless, odorless emitted from for certain rocks
underground
Why are we doing all of this?
 Properties
of atoms correlate with the
number and energy of electrons
 Electron configurations are used to
summarize the distribution of electrons
among the various orbitals
Practice
3-3 Practice
Write the complete electron
configurations and noble gas
shorthand #1-4
Practice

Refer to a periodic table and write the
electron configurations of these atoms.
Write the configurations using shorthand
notation.
Zn

I

Cs
1.
2.
The f-block is inserted into to
the d-block
Find the electron configuration
of Au

Locate Au on the periodic table
Find the electron configuration
of Au

Au [Xe]

The noble gas core is Xe
Find the electron configuration
of Au

Au [Xe]6s2

The noble gas core is Xe
From Xe, go 2 spaces across the s-block in the 6th row
 6s2

Find the electron configuration
of Au

Au [Xe]6s24f14

The noble gas core is Xe
From Xe, go 2 spaces across the s-block in the 6th row
 6s2
Then detour to go 14 spaces across the f-block  4f14
 note: for the f-block, n = row – 2 = 6 – 2 = 4


Find the electron configuration
of
Au
2 14
9

Au [Xe]6s 4f 5d

The noble gas core is Xe
From Xe, go 2 spaces across the s-block in the 6th row  6s2
Then detour to go 14 spaces across the f-block  4f14
 note: for the f-block, n = row – 2 = 6 – 2 = 4
Finally go 9 spaces into the d-block on the 6th row  5d9
 note: for the d-block, n = row – 1 = 6 – 1 = 5



Electron configuration of ions
What is an ion?
 How many electrons does Cl1- have?



How many electrons does Ca2+ have?


What is the electron configuration for the
chloride ion?
What is the electron configuration for the
calcium ion?
What do you notice?
Practice

Draw the orbital diagram for sulfur.


What ion does sulfur want to form and why?
Draw the orbital diagram for Potassium.

What ion does sulfur want to form and why?
What does this mean
 Properties
of atoms correlate with the
number and energy of electrons

Atoms like to have full outer shells.
Why is this important
Valence electrons

Electrons in the outermost energy level

Where all the action occurs
Practice

Whiteboard - Atomic Structure (continued)
Team



Write the electron configuration for silver.
Write the noble gas configuration for silver.
What element has the following electron
configuration?
1s22s22p6 3s23p64s23d4
Today we use aspects of line
spectrum to identify elements,
compounds and mixtures?

UV-Vis Spectrometer
Distances and types of stars
 Blood test- carbon monoxide poisoning
 Mobile weapons detectors
 Chlorophyll

How we determine these energy
levels?