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Electrons in Atoms
Name: ___________________
INTRO: Periodic Table of the Elements
metals
-comprise most of the periodic table (________)
-lose electrons to form ___________________ called ___________
-properties; ___________________________________________________________
__________________________________________________________________
nonmetals -located in the upper right “______________” and ______________
-gain electrons to form ____________________ called ___________
-properties; ___________________________________________________________
_____________________________________________________________________
semimetals – called ____________________
-
have properties of both ______________________________
(for instance, they are often _________________________)
-
located on either side of the “____________”
noble gases – called “inert” gases (unreactive)
- don’t react with other elements because their outermost energy level is filled
- located in the far right column
group – vertical column of elements (____________________________________)
-
for group A elements: group # = __________________________
The arrangement of the Periodic Table is such that elements with similar chemical and
physical properties appear within a column. It is the configuration of the outer shell electrons
that determines how an element will react (bond).
Common Group Names:
1A (1);
_______________________________
2A (2):
_______________________________
7A (17)
_______________________________
8A (18)
_______________________________
period - horizontal row of elements
-
period # = # energy levels
energy level
1
2
3
4
5
max. # e2
8
18
32
32
8 *
The outermost energy level of an atom can hold a maximum of ____________________.
stable octet – ____________________________________________________________________
-
this is the configuration of ____________________ and is the most ____________
Atoms react to try and attain a stable octet when they combine to form compounds.
Law of Definite Proportions – _____________________________________________________
_______________________________________________________________________________
Group A Elements – called _____________________ elements
-
show entire range of _____________________________
-
energy levels beneath the _________________________
Group B Elements – called the _____________________________
-
may have more than one _____________________
-
energy levels beneath the outermost have more than __________________ and
may get ___________________________
-
Inner Transitional Metals ________________________________________
1. lanthanides _______________________________________________
2. actinides _________________________________________________
A. LIGHT AND THE QUANTUM CONCEPT
light –
Electromagnetic Spectrum
radio waves radar microwaves infrared visible light ultraviolet x-rays gamma rays cosmic rays
ROYGBIV
Low frequency
wavelength (
frequency (
High frequency
) (lamda) –
) (nu) –
hertz (Hz) –
wavelength and frequency are inversely related:
Quantum or photon –
The energy of a quantum,
where h is Plank’s Constant
The amount of radiant energy absorbed or emitted
Therefore,
B. ATOMIC EMISSION SPECTRA
(c =
speed of light :
)
When an element is heated by passing electricity through its vapor :
.
When an atom absorbs energy:
.
Atomic emission spectrum –
(

line spectra

each element
(like a fingerprint -
C. DEVELOPMENT OF ATOMIC MODELS
1. JJ Thompson –

2. Ernest Rutherford –

Electrons around a dense nucleus; atom mostly empty space
3. Niels Bohr -

energy levels –
Quantum of energy –
4. Schrodinger –



D. ATOMIC STRUCTURE
)
)
Atoms contain
.
nucleus –
electrons –
energy levels (shells) –
-
1
max # e- : ( )
2
3
( )
(
4
)
(
)
stable octet E. SUBDIVISIONS OF ENERGY LEVELS
period # on the periodic table =
Within each energy level,
energy level # =
energy level
1
2
3
4
F. ATOMIC ORBITALS
.
=
sublevels
1
2
3
4
Within each sublevel,
orbital –
sublevel
max # e-
orbitals
( )
( )
( )
( )
s orbitals are
p orbitals are
d orbitals are
f orbitals are
s orbitals
p orbitals
x y z
y
d orbitals
y
z
z
2s
x
1s
x
px
px
equal probability of finding 1st or 2nd
“p” electron in either of the 2 lobes
or both electrons within 1 lobe

At higher energy levels

When all orbitals of a sublevel are filled
G. ELECTRONS IN ORBITALS
.
=
:
One e- spin
(
)
and the other opposite e- spin
H. IMPORTANT RULES

Aufbau Principle –

Hund’s Rule –

Pauli Exclusion Principle –
(

)
2n2 Rule –
How many sublevels, orbitals and electrons
could be contained in the 8th energy level?
n
=
n
=
n2
=
energy level
n =
sublevels
n =
orbitals
n2 =
2(n2) =
electrons
How many sublevels, orbitals and electrons could be contained in the 11th energy level?
I. ELECTRON CONFIGURATIONS
& ORBITAL NOTATIONS
1
2
3
4
2(n2) =
1
H
11
Na
2
He
12
Mg
3
Li
13
Al
4
Be
14
Si
5
B
15
P
6
C
16
S
7
N
17
Cl
8
O
18
Ar
9
F
Compare Neon and Argon:
10
Ne
electron configuration – the arrangement of e- around the nucleus of an atom in its ground state
orbital notation – shows the distribution of electrons (as arrows) in the orbital boxes of a sublevel
shorthand electron configuration – the e- config. of an atom using the previous noble gas
as a starting point
condensed electron configuration – the e- config. of an atom that shows the number of electrons
present in each energy level (listed vertically)
electron dot formula or Lewis Dot diagrams: shows the arrangement of valence (outer shell)
electrons around an atomic symbol.Take into account the electrons from the highest energy levels
s and p sublevels. Write the symbol for the element use dots to represent electrons.
Place the dots one on each side before you pair them up (just like filling in orbitals).
Bonding: When elements bond, combine to form compounds, only the electrons in the
outer shell (energy level) are involved. Chemists use __________________ to show these
outer shell electrons.
Write the shorthand electron configuration
N:
He 2s2 2px1y1z1
e- dot structures:
Write the condensed electron configuration
Mg:
N
F:
Mg
2
7
P:
F
P
All transitional metals and inner transitional metals have a completed
s sublevel so their Lewis Dot Diagrams all look the same.
Shorthand electron configuration
Ex: Fe
Lewis Dot
Fe
Pm
Pm
**Because electrons want to be in the orbital with the lowest energy,
(AUFBAU PRINCIPLE), There are some exceptions to how the electrons fill up.
Orbital Energy
Highest
part full
Lowest
Chromium - Cr
½ full
Molybdenium -Mo
full
Copper – Cu
empty
Silver – Ag
J. USING THE PERIODIC TABLE FOR ELECTRON CONFIGURATIONS
Energy sublevels overlap because
s block –
2
p block –
6
d block –
10
f block –
s
14
p
d
f
Remember:
Using the periodic table write the complete electron configuration for the following elements:
cond. e- cofig for I:
Ni (#28)
I (#53)
Au (#79)
K. QUANTUM NUMBERS OF ELECTRONS
The energy state of electrons in atoms can be described by a set of four numbers that describe
a) distance from the nucleus b) shape c) position in 3D space, and d) spin.
Quantum number
symbol
description
values
a)
Principal
n
b)
Orbital
l
c)
Magnetic
ml
d)
Spin
ms
Principal quantum n = 1 
Orbital quantum
l
=0 
Principal quantum n = 2 
Orbital quantum
l
=1 
Principal quantum n = 3 
Orbital quantum
l
=2 
Principal quantum n = 4 
Orbital quantum
l
=3 
Spin quantum ms = +½ 
Magnetic quantum ml = 0 
(s)
Spin quantum ms = -½ 
0
Magnetic quantum ml = 1 
Magnetic quantum ml = 2 
(p)
x
-1
0
+1
-1
0 +1
+2
(f)
-3 -2
Principal
Energy level 1: n =
z
(d)
-2
Magnetic quantum ml = 3 
y
-1
0 +1
orbital
l=
possible electron sites:1s1 =
1s2 =
+2 +3
magnetic
ml =
spin
ms =
Principal
Orbital
Magnetic
l=
Energy level 2: n =
ml =
ml = 0
(sublevel s  1 orbital)
Spin
ms =
ml = -1 0 +1
(sublevel p  3 orbitals)
2s
2px
2py
2pz
2s1 =
2px1 =
2py1 =
2pz1 =
2s2 =
2px2=
2py2 =
2pz2 =
Principal
Orbital
Magnetic
l=
Energy level 3: n =
ml =
ml = 0
(sublevel s  1 orbital)
Spin
ms =
ml = -1 0 +1
(sublevel p  3 orbitals)
3s
3px
3py
3d
energy level 3  n =
sublevel d 
l=
(sublevel d  5 orbitals)
ml =
-2
-1
0
+1 +2
3pz
Principal
Orbital
Magnetic
l=
Energy level 4: n =
ml =
4s
Spin
ms =
4p
possible electron sites:
4d
4f
What are the quantum numbers for the last placed electron in each of these atoms?
1. S (#16)
2. Ag (#47)
3. Ba (#56)
4. U (#92)
 When drawing the electron dot structure for an atom of an element, the diagram shows
the VALENCE electrons, that is, the electrons in the HIGHEST energy level of that atom.

When writing the quantum numbers for an atom of an element, the numbers are written for
LAST placed electron, that is, the LAST ITEM in the electron configuration.
For each of the following elements:
a. Give the shorthand e- configuration
b. Give the orbital notation
1. Na (#11)
2. Ru (#44)
3. Eu (#63)
4. At (#85)
c. Give the electron dot formula (valence e-)
d. Give the quantum #s for the last placed e-