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Atomic Theory Class #1
Penny Lab ASAP.
Check your grades!
OB: Students will examine basic
structure of the atom, learn what the
numbers on the Periodic table mean, and
look at electron orbitals.
Take out your WHITE periodic tables now.
All atoms are made up of three sub-atomic (smaller than atoms) parts. They are the
1.
Parts of
the atom
Particle
Charge
Symbol
Mass
Location
All atoms are made up of three sub-atomic (smaller than atoms) parts. They are the
Parts of
the atom
Particle
Charge
Symbol
Mass
Location
proton
+
+
p
1 amu
nucleus
neutron
Ø
n°
1 amu
nucleus
e
zero in
high
school
Flying
around the
nucleus
electron
-
2. The mass of an electron is NOT ZERO, but it’s so small, about 1/1750 of a
proton or neutron, that we will disregard it’s mass. It’s an intro class, and we can’t
measure these masses in our class anyway, but it’s not zero in the real world.
The nucleus is the small, dense center of an atom where the protons and neutrons live.
Electrons fly around outside, relatively far away.
In this model, the nucleus is the
yellow ball in the middle. It
does not show it, but inside must
be three protons and probably 4
neutrons.
This is a model of atom #3, which
is LITHIUM.
It’s a cartoon, it’s not even
what we think atoms look like,
but it’s cute.
The mass of all atoms are measured in super tiny masses
called AMU, or ATOMIC MASS UNITS.
The vocabulary is building up already. This is another topic
to NOT FALL BEHIND ON.
Masses for the subatomic particles (approximate)
Protons = 1 amu each
Neutrons = 1 amu each
Electrons = zero mass in high school chem
3. Atomic
Mass
4. Atomic
Number
5. Electron
Configuration
12.011
6
2-4
6. Atomic Mass Numbers will be rounded to the nearest
whole number (they are not really whole numbers, we’ll get
to that later)
7. Mass Number = mass of protons plus neutrons
Mass = p+ plus n°
8. The mass of mercury is 201, so mercury has a
total of 201 protons plus neutrons.
How many of each? Let’s learn how to figure this out
Atomic Mass of Hg = 201 amu
Minus the protons
Equals the n°
- 80 p+
121 n°
the n° + p+ = mass
Or, n° = mass - p+
9. Let’s do TIN, Sn
An atom of tin =
which is the total p+ + n°
Minus atomic #
which is the # p+
left over, which are the neutrons
9. Let’s do TIN, Sn
An atom of tin = 119 amu which is the total p+ + n°
Minus atomic # - 50
which is the # p+
69 left over, which are the neutrons
This works for all 118 different atoms, all of them!
10. All atoms are electrically
neutral, the number of p+ = eThe positives = the negatives.
Always.
Every atom is neutrally charged.
The positive protons + negative
electrons BALANCE.
11. How many p+, n° and e- are in these atoms?
In
Nb
Ba
11. How many p+, n° and e- are in these atoms?
In
Nb
Ba
Mass = 115
Mass = 93
Mass = 137
Minus the At # - 49
Minus the At # - 41
Minus the At # - 56
Neutrons = 66
Neutrons = 52
Neutrons = 81
12. Calcium can also be written properly as:
Atomic mass
Atomic number
40
20
Ca
14. Write the Formal Symbols for these
atoms: mercury, chlorine, and copper
Calcium can also be written properly as:
40
20
Atomic mass
Atomic number
Ca
Write the Formal Symbols for these atoms:
mercury, chlorine, and copper
201
80
Hg
35
17
Cl
64
29
Cu
Electrons don’t just fly around
willy nilly
(I like that expression, and it fits)
15. Electrons STAY IN orbitals, which are also energy levels.
16. The further away from the nucleus, the higher the energy level the
orbital is. The closer to the nucleus, the LOWER their energy level is.
17. The orbitals are only so big, they fit certain numbers of electrons.
n = 1 (the first orbital) fits up to 2 electrons total
n = 2 (the second orbital) fits up to 8 electrons total
n = 3 (the third orbital) fits up to 8 electrons too, (sometimes up to 18)
Etc. More to come on this.
Let’s look at the periodic table now
18. Find silver, how many electrons does it have?
19. Find scandium, what is the electron configuration
& total number of electrons?
20. Find the atom S, what is the name of this atom,
how many p+ does it have? How many e- ?
21. Find oxygen, how many neutrons, what is it’s
chemical symbol?
Let’s look at the periodic table now
18. Find silver, how many electrons does it have? 47
19. Find scandium, what is the electron configuration
& total number of electrons? 21, 2-8-9-2
20. Sulfur has 16 p+ and also has 16 e- ?
21. Find oxygen, how many neutrons, what is it’s
chemical symbol? O has 16 n°
22. For any atom, the atomic number is the number of
protons, which equals the number of electrons.
The electron configuration always adds up to the atomic
number.
Examples:
23. Na #11 has a 2-8-1
or 2 + 8 + 1 = 11 total e―
24. C #6 has a 2-4 configuration or 2 + 4 = 6 total e―
25. K #19 has a 2-8-8-1 configuration
or 2 + 8 + 8 + 1 = 19 total e―
Atomic Theory Class #2
OB: students will review the models of the
atom through scientific history, learning how
ideas progressed and were dismissed as new
information was developed.
Most famous chemists had
remarkable mustaches.
That’s the easiest way to
keep track of who’s who in
science!
About 2400 years ago a philosopher named
Democritus said:
26.
If you took anything and cut it in half, and in half, and
in half, over and over, sooner or later you would get to a
piece of this stuff that could not be cut in half again.
That piece was called an
ATOMOS
(he was Greek)
And that’s the start of chemistry.
You could have an ATOMOS of a rock, of a fish, of a diamond, etc.
The smallest piece of anything, that could not be cut again was to
be known as an ATOM of that stuff.
A good name, and it stuck.
The first of many
mustaches in our course!
In the early 1800’s a man named John Dalton thought he could
invent chemistry, it had to be longer than a singe word.
He said…
27.
1. All substances were made up of atoms.
2. Each kind of atom had its own mass, different from the
masses of the other kinds of atoms.
3. All atoms were built like billiard balls (a game he liked to play)
His model was called the
BILLIARD BALL MODEL
Dalton came up with what is now called the
28. Atomic Theory
This is so important I can’t highlight it enough!
1. All elements are composed of individual kinds of atoms.
2. Atoms of one element are identical. Atoms of
different elements have different masses.
3. Atoms can physically mix with other atoms. Atoms can
also chemically combine with other atoms IN SIMPLE
WHOLE NUMBER RATIOS, to form new substances.
4. Chemical reactions change the arrangement of atoms,
but they do not become different kinds of atoms.
29. Dalton did not know of protons, neutrons or electrons.
He was brilliant, but had little science ability in 1803.
You know a lot more about atoms now than he ever did!
30. Around 1897
J. J. Thomson discovers
the electron!
Look at the hair on that man’s lip!
31. Thomson did a variety of experiments, some using
what’s called the cathode ray tube, to detect and measure
electrons. He found the first subatomic particle, which was
negatively charged.
32. His model of the atom is called the PLUM PUDDING MODEL,
after what his wife’s dessert looked like! He put his newly
discovered negative electrons into the positive “mush” of the
atom. If Mrs. Thomson made him chocolate chip cookies instead,
the model would be the chocolate chip cookie model, with the
cookie being positive, offset by the negative electrons – the chips!
He knew that the atoms were neutral.
In 1908, my chemical hero, Earnest J. Rutherford discovers the nucleus! - and much more
about the atom than previous scientists.
Rutherford’s
33. Gold Foil Experiment
He discovers the nucleus!
The gold foil experiment was one of the
top 10 experiments of all time, and cost
him about fifty bucks. Wow!
34. Details of the GOLD FOIL experiment to memorize and share with your friends.
35. What does this gold foil experiment prove?
1. Atoms are mostly empty space
since most of the alpha particles pass though the foil like it’s
not really there.
2. Atoms are neutral (he knew this) so the nucleus
must be dense and positively charged
since the alpha particles which are positive didn’t stick, and they
dinged off of something big every once in a while
3. Neutral atoms must therefore have electrons
outside the nucleus
flying around outside (like planets?) made sense.
Problems with this new theory of
Rutherford’s
How can atoms be mostly empty space? How can
they be mostly “not” there?
How can these negative electrons fly around a
positive center, but they never are attracted into this
positive nucleus? Why not? They just keep flying?
They never use up their energy? Ever? Really?
How far away are these electrons Ernie - and do
they just fly willy-nilly, or is there a system to them?
Rutherford was right, but he needed some help. In 1913, one of his students, a
man with a plural first name, comes to his rescue.
Niels Bohr
Niels Bohr is able to do some very funky
math, (physics level + Nobel Prize style
math) and he proves Rutherford is correct.
37. He shows that for hydrogen, if the electron fly
at the right speed, and the right distance, it will
somehow never run out of energy, and never
collapse into the nucleus.
And it doesn’t, does it? You already know he’s right
even though you can’t do the math.
None of the atoms collapses, not a one, and even
though he can’t do the math for even 2 electrons,
his proof is enough to save the modern model of
the atom, central nucleus, flying electrons.
38. Niels Bohr further determines that
1.
Electrons fly in specific orbits, as planets that are
flying around the sun, nicely.
2. He showed that each orbit was really also an
energy level. The smallest orbit closest to the
nucleus was the lowest energy level.
3. Electrons could gain a specific amount of energy,
an amount called a _______________, which
enable the electrons to “jump” up to a
______________________ energy level or orbit.
38. Niels Bohr further determines that
4. Since every atom was unique (different numbers
of protons and electron configurations) it took
___________ amounts of energy to make these
upward “jumps” possible.
5. The electrons, in this new ___________ state,
were less stable than the were in the normal or
___________ state. They’d have to give back this
UNIQUE AMOUNT of energy the just gained in order
to return to the ground state.
Orbits was wrong, we understand them as ORBITALS now.
39. The modern model of the atom has been
developed by many scientists over a long
period of time.
40. It’s called the Wave-Mechanical Model
because the electrons sometimes act like waves
of energy, and sometimes like little bits of
mechanical matter with a negative charge.
41. Because of the new math, the QUANTUM
MATH, this model is more concerned with the
STATISTICAL PROBABILITY of finding an
electron’s location MOST OF THE TIME
Electron orbitals are still energy levels, they just aren’t so neat.
In this model/diagram, imagine that this is a photograph of
a Helium atom (impossible really) taken about 1000 times
on to the same piece of film, then printed overlapping. Each
dot represents where the electrons were at some point.
Electrons are a lot
like Teenagers.
Atomic Theory Class #3
OB: The Patterns of the Electron Orbitals,
Ground State vs. Excited State, and SPECTRA
Take out your periodic tables
NOW, fill in the chart of the
electron configurations
Copy the electron configurations from Periodic Table
Group
1
Group
2
Group
15
Group
16
Group
17
Group
18
42
lithium
beryllium
nitrogen
oxygen
fluorine
neon
43
sodium
magnesium
phosphorous
sulfur
chlorine
argon
44
rubidium
strontium
antimony
tellurium
iodine
xenon
These are the GROUND STATES or
Lowest energy states (this is NORMAL)
Copy the electron configurations from Periodic Table
42
43
44
Group 1
Group 2
Group 15
Group 16
Group 17
Group 18
lithium
beryllium
nitrogen
oxygen
fluorine
neon
2-1
2-2
2-5
2-6
2-7
2-8
sodium
magnesium
phosphorous
sulfur
chlorine
argon
2-8-1
2-8-2
2-8-5
2-8-6
2-8-7
2-8-8
rubidium
strontium
antimony
tellurium
iodine
xenon
2-8-18-8-1
2-8-18-8-2
2-8-18-18-5
2-8-18-18-6
2-8-18-18-7
2-8-18-18-8
These are the GROUND STATES or
Lowest energy states (this is NORMAL)
45. The 1st orbital holds up to _____electrons.
The 2nd orbital holds up to ______ electrons
46. The 3rd orbital holds up to _______ (or _____ !)
electrons (it’s funky)
47. The 4th orbital holds up to _______ (or _____!)
electrons (it’s also funky)
48. All electron configurations on the periodic table are
in the LOWEST ENERGY state, also called the
___________________________________________________________
45. The 1st orbital holds up to 2 electrons.
The 2nd orbital holds up to 8 electrons
46. The 3rd orbital holds up to 8 or 18 electrons (it’s funky)
47. The 4th orbital holds up to 18 or 32 electrons
48. All electron configurations on the periodic table are
in the LOWEST ENERGY state, also called the
Ground State, which is NORMAL
Fill in POSSIBLE EXCITED STATE electron
configuratons for these atoms
ground state
A possible excited state
49
Lithium 2-1
Lithium
50
Silicon 2-8-4
Silicon
51
Potassium 2-8-8-1
Potassium
52
Aluminum 2-8-3
Aluminum
53
Boron
Boron
2-3
Fill in POSSIBLE EXCITED STATE electron
configurations for these atoms
ground state
A possible excited state
49
Lithium 2-1
Lithium
1-2
50
Silicon 2-8-4
Silicon
2-7-5
51
Potassium 2-8-8-1
Potassium 2-8-7-2
52
Aluminum 2-8-3
Aluminum 2-7-4
53
Boron
Boron
2-3
2-2-1
(or 1-8-5, or 2-8-3-1)
(or 2-7-8-2)
(or 2-7-3-1, or 2-8-2-1)
(or 1-4, or even 2-1-1-1)
In INTRO CHEM it is NOT POSSIBLE for you, or me, to know exactly which electrons move
“up” to higher orbitals. Keep it Simple Silly Rabbits, or else you will get confused.
54. Ground + Excited State electron configurations have the
_______________________, they are just in _______________ places.
55. What is KISS?
_________________________________________________________
And that means what here??
56. How do electrons get excited? They absorb energy in
______________
________________
and release it as __________________________ light called
____________________________.
54. Ground + Excited State electron configurations have the
Number of Electrons, they are just in Different places.
55. What is KISS? And what does it mean here?
Keep it simple silly, don’t move a bunch of electrons around, you will
lose count and make silly errors.
56. How do electrons get excited? They absorb energy in
Unique quantities,
and release it as Visible light called SPECTRA.
THINK
Atom
Number of protons in
nucleus with positive charge
pulling
on the electrons
Ground State
Possible
Excited
State
57
Sodium Na
______ protons
2-8-1
2-7-2
58
Magnesium Mg
______ protons
2-8-2
2-7-3
Why is the spectra different for Na
and Mg if they both move 1 electron
nd
rd
from 2 to 3 orbital?
THINK
Atom
Number of protons in
nucleus with positive charge
pulling
on the electrons
Ground State
Possible
Excited
State
57
Sodium Na
11 protons
2-8-1
2-7-2
58
Magnesium Mg
12 protons
2-8-2
2-7-3
With different numbers of protons
pulling inward, it takes a different
(unique) amount of energy to excite
electrons in these different atoms.
No matter how the energy was added in, the energy coming out is emitted as visible light,
which we can see (you can see).
59. Each unique amount of energy given off is visible as different colors, which we can see with
our eyes. This light given off WHEN ELECTRONS RETURN TO THE GROUND STATE IS CALLED
_____________________________
60. The spectra is a ______________________ of light, we see as one color but is made up of
__________________ colors. Our eyes blend it into one shade. Inexpensive devices
(similar to prisms) break up this single color spectra, into what is
called a _____________________-graph.
Each line is part of the spectra, and is like a UNIQUE finger print for that atom or compound.
Scientists (and you too) will be able to determine what atoms are present by what spectra is
emitted by unknown substances. We just compare the spectra measured, to the known
spectrographs. This can be used in a lab to do CSI work, or through telescopes - to know what
substances exist on other planets. The unique spectra that the same throughout the Universe.
No matter how the energy was added in, the energy coming out is emitted as visible light,
which we can see (you can see).
59. Each unique amount of energy given off is visible as different colors, which we can see with
our eyes. This light given off WHEN ELECTRONS RETURN TO THE GROUND STATE IS CALLED
SPECTRA
60. The spectra is a
Mixture
of light, we see as one color but is made up of
MANY colors.
Our eyes blend it into one shade. Inexpensive devices
(similar to prisms) break up this single color spectra, into what is
called a
SPECTRAGRAPH.
Each line is part of the spectra, and is like a UNIQUE finger print for that atom or compound.
Scientists (and you too) will be able to determine what atoms are present by what spectra is
emitted by unknown substances. We just compare the spectra measured, to the known
spectrographs. This can be used in a lab to do CSI work, or through telescopes - to know what
substances exist on other planets. The unique spectra that the same throughout the Universe.
Atomic Theory Class #4
OB: what are isotopes and
why are they so important?
You will need a calculator and your
reference tables out.
Take out your 39 atoms handout as
well, it’s going into the in box soon.
John Dalton once said that all atoms of an element are identical,
because at that time he could not imagine that there were any
subatomic particles. He thought all the differences in atoms were
that they had different masses, and that alone accounted for all
the different properties.
He was the father of modern chemistry, and you already are more
educated than him. It turns out he was half right.
He should have said that:
All Atoms Of An Element Are Chemically
Identical. They all react alike, & they have
the same chemical properties.
They are NOT PHYSICALLY IDENTICAL.
61. But, some atoms have a
______________________________________________.
These “different” atoms are called ______________
There are 118 types of atoms, but there are almost
__________________ different kinds of atoms.
62. Each kind of atom comes in a variety of masses,
each type of atom forms many different ___________.
61. But, some atoms have a different number of neutrons.
These “different” atoms are called ISOTOPES
There are 118 types of atoms, but there are almost
1500 different kinds of atoms.
62. Each kind of atom comes in a variety of masses,
each type of atom forms many different ISOTOPES.
FILL IN THIS CHART of the common Isotopes of Neon
ISOTOPE →
63
# protons
64
# electrons
65
# neutrons
66
MASS in amu
Neon-20
Neon-21
Neon-22
FILL IN THIS CHART of the common Isotopes of Neon
ISOTOPE →
Neon-20
Neon-21
Neon-22
63
# protons
10 p+
10 p+
10 p+
64
# electrons
10 e-
10 e-
10 e-
65
# neutrons
10 n°
11 n°
12 n°
66
MASS in amu
20 amu
21 amu
22 amu
67. These 3 different ISOTOPES of neon
are _____________ identical but all
have a different _______.
68. They have the same number of
protons + electrons, but different
numbers of _____________.
69. Only the ______ is affected, not their
chemical ________.
67. These 3 different ISOTOPES of neon
are CHEMICALLY identical but all
have a different _______.
68. They have the same number of
protons + electrons, but different
numbers of NEUTRONS.
69. Only the MASS is affected, not their
chemical PROPERTIES.
Carbon has 2 main isotopes, C-12 and C-14. The carbon 14 is
the radioactive kind, which we will discuss in great detail later
in the year.
C-12 makes up 99.45% of all the carbon in the world.
C-14 makes up the rest, just 0.55% of the carbon.
70. Together they make up 100% of the carbon.
71. What is the ACTUAL average atomic mass of carbon atoms, the number on the
periodic table in the atomic mass space? ________________
Here’s how we figure that out (do this math):
(12 amu)(.9945) =
(14 amu)(0.0055) = ______________________
(12 amu)(.9945) = 11.934 amu
(14 amu)(0.0055) = 0.077 amu
12.011 amu
Just like the periodic table says.
Decimals come about because the proportions or
percentages of the isotopes are not even steven.
Most of the carbon is C-12, so the weighted average
atomic mass is very close to 12.
The most common isotope is the one that has the mass
closest to the mass on the periodic table.
Average Weighted Atomic Mass is the mass listed on our
periodic tables. They take into account the mass of each
isotope AND the proportions that those isotopes make up of all
of that kind of atom. Scientists measure these proportions all
the time (and sometimes it changes the numbers on the
periodic table when they realize that the proportions are a little
different than they thought.
73. The mass of an isotope (in HS Chem) is always a WHOLE NUMBER of amu,
because they have a whole number of ______________ + _______________.
But the PROPORTIONS are funky, which is where the decimals come from.
Average Weighted Atomic Mass is the mass listed on our
periodic tables. They take into account the mass of each
isotope AND the proportions that those isotopes make up of all
of that kind of atom. Scientists measure these proportions all
the time (and sometimes it changes the numbers on the
periodic table when they realize that the proportions are a little
different than they thought.
73. The mass of an isotope (in HS Chem) is always a WHOLE NUMBER of amu,
because they have a whole number of PROTONS + NEUTRONS.
But the PROPORTIONS are funky, which is where the decimals come from.
74. A new element named Arbuiso is discovered (A).
It has two isotopes, A-44 and A-45. 95.00% of all
this Arbuiso has mass of 44 amu, while the rest has
mass of 45 amu.
What is the weighted average atomic mass of this
cool new metallic element?
74. A new element named Arbuiso is discovered (A).
It has two isotopes, A-44 and A-45. 95.00% of all
this Arbuiso has mass of 44 amu, while the rest has
mass of 45 amu.
What is the weighted average atomic mass of this
cool new metallic element?
(44 amu)(.9500) =
41.80 amu
(45 amu)(.0500) = + 2.25 amu
44.05 amu
average weighted atomic mass
75. Unknown element X has three isotopes, X-23, X-24, and
X-25. The first isotope makes up 75.00% of all of this
element. X-24 makes up 20.0%, while the last isotope X-25
makes up just 5.0% of all this unknown element.
What is it’s average weighted atomic mass?
(hint, same type of math, but there are 3 lines this time)
75. Unknown element X has three isotopes, X-23, X-24, and
X-25. The first isotope makes up 75.00% of all of this
element. X-24 makes up 20.0%, while the last isotope X-25
makes up just 5.0% of all this unknown element.
What is it’s average weighted atomic mass?
(hint, same type of math, but there are 3 lines this time)
(23 amu)(.750) =
17.25 amu
(24 amu)(.200) =
4.80 amu
(25 amu)(.050) = + 1.25 amu
23.3 amu
Does that make sense, about 23 amu?
Review
76. State the Objective #1 in the NYS Chemistry Curriculum for Chemistry…
Review
76. State the Objective #1 in the NYS Chemistry Curriculum for Chemistry…
The modern model of
the atom has evolved
over a long period of
time through the work
of many scientists.
Scientist Name
77
78
79
80
81
82
many
Model Name
Details
77
Scientist Name
Model Name
Details
Democritus
(not a scientist)
x
The smallest part of anything was to be
called “atomos” which is Greek for Atom
78
John Dalton
Billiard Ball
Atoms were like small hard spheres of
different mass. 4 part Atomic Theory
(important and coming soon)
79
J. J. Thomson
Plum Pudding
Discovered the Electron, put it “into” a
positive mush, that kept atoms neutral.
x
Gold foil experiement proves electrons fly
around the outside of a positive nucleus.
(coming soon)
Niels Bohr
Planetary
Put electrons into energy levels called
ORBITS, discovered and explained spectra
many
Modern, or WaveMechanical
Electrons are not in orbits, but rather in
energy levels called orbitals. Fuzzier and
more in tune with complex quantum math.
80 Ernest J. Rutherford
81
82
83. The 4 points of Dalton’s Atomic Theory
1.
2.
3.
4.
83. The 4 points of Dalton’s Atomic Theory
1. All elements are composed of individual kinds of atoms.
2. Atoms of one element are identical. Atoms of
different elements have different masses.
3. Atoms can physically mix with other atoms. Atoms can
also chemically combine with other atoms IN SIMPLE
WHOLE NUMBER RATIOS, to form new substances.
4. Chemical reactions change the arrangement of atoms,
but they do not become different kinds of atoms.
84. Draw the Gold Foil Experiment with labels
84. Draw the Gold Foil Experiment with labels
85. Explain what Rutherford Discovered and detail the problems with his new ideas.
85. Explain what Rutherford Discovered and detail the problems with his new ideas.
With the Gold Foil experiment, Rutherford showed:
An atom consists of a positively charged nucleus and is
surrounded by electrons that spin around it. Electrons and
neutrons are held together by opposite charge. The size of
the nucleus is extremely small as compared to the size of
the whole atom. The atom's entire mass is concentrated
in the nucleus.
Problems: He could not explain the stability of an atom,
why didn’t the electrons collapse to the + charged nucleus,
or fly away? The electrons revolving around should lose
energy, which should slow them, causing collapse into the
nucleus, but this didn’t seem to happen. The atom being
99% empty space should also mean we should almost be
able to walk through walls, or see through everything, but
we can’t.
86.
Describe the Bohr Model (planetary) and spectra.
86.
Describe the Bohr Model (planetary) and spectra.
Bohr mathematically proved that if the electron
of the hydrogen atom traveled at a set distance,
at a set speed from the nucleus, somehow, it
would never lose energy and never fly away
and never be sucked in to the positive center of
the atom.
The math was too hard to prove for any other
atom, but he concluded, they existed, the
electrons spun around those nuclei, so just
because he couldn’t do the math didn’t mean it
wasn’t still true for them.
86.
Describe the Bohr Model (planetary) and spectra.
He further stated that the electrons all existed in
ORBITS, and that each orbit was also an
energy level. Electrons in the lower orbits had
less energy than electrons in the higher orbits.
And, he showed that the electrons lived in the
ground state, or lowest energy levels possible
most of the time. That was their NORMAL
state. When looking at the atoms in increasing
atomic number, the electrons filled these orbits
in a simple pattern, lowest energy levels first.
86.
Describe the Bohr Model (planetary) and spectra.
Finally, electrons of an atom could gain a
specific amount (a quanta) of energy, and get
excited. The electron could move up to a higher
energy orbit. This was unstable, and when the
electron returned to the ground state, this
unique quanta of energy was released, as
unique visible light called spectra. We see
spectra as a mixture of color (one color) but the
light is many specific colors, all at specific
wavelengths, a sort of optical fingerprint for
each substance.
87. What’s the difference between orbit & orbital?
87.What’s the difference between orbit & orbital?
Bohr said orbit for energy level. Now we have
electrons in energy levels called ORBITALS.
Orbit implies radius and a “neat” simple
spinning around the nucleus. Orbital
means “zone”, which is fuzzier in shape.
NEAT ORBITS
FUZZY ORBITALS
88.
What’s the difference between SPECTRA and a SPECTRAGRAPH?
The word “open” has neon
gas that is excited by
electricity. The spectra
given off we see as
ORANGE light with our
eyes. That’s the mixture
we see all at once.
As seen through a refractive lens, we
can see the unique colors that are
broken apart by the prism of the lens.
For a few dollars more the device used
to see this, with numerals to measure
the wavelengths in nanometers
(quantitative measuring)
Atom
Ground state
electron configuration
Possible excited state
configuration
# of electrons
is always
89
Mg – 12
2-8-2
2-7-3
12
90
Al – 13
2-8-3
2-7-4
13
91
C–6
2-4
2-3-1
6
92
Ca – 20
2-8-8-2
2-8-8-1-1
20
93
Fe – 26
2-8-14-2
2-8-13-3
26
Mark the correct electron configurations OK.
Fix any that are wrong and state why they are wrong below.
94. Mg ground 2-8-2 OKAY
95. F ground 2-7 OKAY
96. He ground 2 OKAY
97. Ne ground 2-8-8 X 2-8 only
98. Mg excited 1-9-2 X only 8e- in 2nd orbital
99. He excited 1-1 OKAY
100. Ne excited 2-8-7-1 X 2-7-1 for neon
101. F excited 2-8 X only 9 total e- for F
102. P ground 2-9-4 X only 8e- in 2nd orbital