Transcript Atomic Structure & Periodicity

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Rhonda Alexander
Principle quantum number
Depends on energy level
n=(1,2,3, …)
Azimuthal quantum number
Shape of orbital-depends on location on periodic chart
If s block then l=0
If p block then l=1
If d block then l=2
If f block then l=3
Atomic Orbitals
1–s
3-p
5–d
7-f
Atomic Orbitals
d - orbitals
l ranges from 0 to n-1.
If n=1, then l=0
If n=2 then l=0,1
If n=3 then l= 0, 1, 2
Angular Quantum Number
• ml represents the individual orbitals of a
given type.
• ml ranges from –l to +l
• ml tells you which p, d, or f orbital the
electron is in
Magnetic Quantum Number (ms): Spin
QuantumNumbers
Quantum Numbers
• n = integer from 1 to 7
• l = 0 to n-1
• ml = -l to +l
1
1
• ms =  or 
2
2
HOW DO WE DESCRIBE THE LOCATION OF
EACH ELECTRON IN AN ATOM?
WITH A SYMBOLIC NOTATION CALLED AN
ELECTRON CONFIGURATION.
An Electron Configuration is a shorthand method of
listing the location of the electrons in an atom. The
system locates each electron by energy level and sublevel.
The number of electrons in each sublevel is indicated
with a superscript. For instance, the electronic
configuration of Sodium is
1s22s22p63s1.
This indicates that there are two electrons located in the
1s orbital, two electrons in the 2s orbital, six electrons in
the 2p orbital and a single electron in the 3s orbital.
Remember:
ENERGY
LEVEL
SUBLEVELS
1
s
2
s
p
s
3
p d
s
4
p d f
NUMBER OF 1
ORBITALS IN
SUBLEVELS
1 3
1 3 5
1 3 5
2
2 6
2 6 10
2 6 10 14
MAXIMUM
# OF e IN
SUBLEVELS
MAXIMUM
3 OF e IN
ENERGY LEVEL
2
8
18
32
7
Filling Orbitals
Follow rules of modern atomic model:
Aufbau Principle -electrons fill from lowest
energy level first
Hund’s Rule -have maximum number of unpaired
electrons
Pauli Exclusion Theory -no electron has same set
of quantum numbers because of electron spin
RULES FOR PLACING ELECTRONS IN ORBITALS
1. Electrons occupy lowest energy orbitals first.
2. An orbital can hold a maximum of 2 electrons.
The Pauli Exclusion Principle must be obeyed.
3. Hund's Rule must be obeyed; when placing
electrons into degenerate orbitals, there must be
one electron in each orbital before any pairing of
electrons can take place. {Degenerate orbitals are
orbitals of the same energy level and sublevel.}
Aufbau Diagram
The Order Electrons Fill
Orbitals
__
__
__ __ __
1s
__
2s
2p
__ __ __ __ __
4s
3d
__ __ __ __ __ __
5s
4d
__
__ __ __
3s
3p
__ __ __
4p
__ __ __ __
5p
6s
Electron Configuration of Zr
1s2 2s2 2p63s2 3p6 4s2 3d10 4p6 5s2 4d2
Practice
• Write the electron configuration of the
following on a separate page.
– Oxygen
– Lithium
– Iron
– Bromine
– Tin
Core Notation of Sn
• Locate Sn on the periodic table
Electron Configuration of Sn
Sn [Kr]
• The noble gas core is Kr
Sn [Kr]5s2
• The noble gas core is Kr
• From Kr, go 2 spaces across the s-block in the 5th row  5s2
Sn [Kr]5s24d105p2
•
•
•
•
The noble gas core is Kr
From Kr, go 2 spaces across the s-block in the 5th row  5s2
Then go 10 spaces across the d-block on the 5th row  4d10
Finally go 2 spaces into the p-block on the 5th row  5p2
Steps
• Locate the element
• Go to the end of the row and up 1 noble
gas
• Write the Noble gas core in brackets
• Continue electron configuration with the
next period
Nobel Gas (Core) & Orbital Diagram
• Refer to a periodic table and write the electron
configurations of these atoms. Use the noble
gas core.
• Zn
• I
[Ar]4s23d10
[Kr]5s24d105p5
•Zn [Ar]4s23d10

4s
    
3d
•I [Kr]5s24d105p5

5s
    
4d
  
5p
Quiz - Quantum Numbers
1. Zn
2. Sb
3. Cs
4. .n = 4
.l = 3
.ml = -3
.ms = -1/2
.n = 3
.l = 2
.ml = +2
.ms = -1/2
.n = 6
.l = 0
.ml = 0
.ms = +1/2
Tb
.n
= 5
.l = 1
.ml = +1
.ms = + 1/2
The Periodic Table
• Is a table that arranges the
elements according to similarities
in their properties.
Dmitri
Mendeleev
Father of the
Periodic Table
Mendeleev’s Periodic Table
(63 known elements)
Developed the Periodic Law that said:
- columns arranged by increasing
atomic mass (not correct)
- rows arranged by chem. & physical
properties
Mendeleev’s Table (cont.)
• Concluded gaps in table were
elements yet to be discovered.
• - led to the search for missing
elements
• - predicted existence of
aluminum, boron, silicon,
germanium
Predicted Properties
Atomic weight
72
Density
5.5 g/cm3
Melting point
825 C
Oxide formula
RO2
Density of oxide
4.7 g/cm3
Chloride formula
RCl4
Observed Properties
72.61
5.32 g/cm3
938 C
GeO2
4.70 g/cm3
GeCl4
Mendeleev’s Original Table
Modern Periodic Table
- Developed by Henry Moseley
- Solved problems in Mendeleev’s
table.
- Periodic law is based on increasing
atomic #, NOT atomic mass.
Structure of the Periodic Table
periods: rows going across,
numbered 1-7
groups: columns going down,
numbered 1-18; aka families
- Elements w/in groups have similar
physical and chemical properties.
The Metals
• located left of zig-zag
or stair-step
Properties
- good conductors
- lusterous
- malleable
- ductile
The Nonmetals
• located right of
zig-zag or stairstep
• Properties:
dull; brittle;
poor conductors,
The Metalloids
• Border zig-zag /
stair-step
except aluminum
and polonium
• Properties:
- some metallic
- some nonmetallic
- semi-conductors
Representative Elements
1
IA
2
IIA
3
4
5
6
7
8
9
10
11 12
13 14 15 16 17 18
IIIA IVA VA VIA VIIA VIIIA
Transition Metals
Inner Transition Metals
metals
nonmetals
Transition Metals
Inner Transition Metals
Elements:
Metals Nonmetals
Groups/Families:
Alkali Metals
Metalloids Transition Metals
Alkali Earth Metals
Halogens
Noble Gases
Inner Transition
Lanthanides
Actinides
Key Terms
• Atomic radius – ½ distance btwn
nuclei of two atoms in a molecule.
• Ionization energy – amt. of energy
needed to remove an e- from an
atom.
• Electronegativity – tendency for an
atom to attract e• Valence e- - e- on outermost energy
level.
6 valence
electrons
5 valence
7 valence
electrons
electrons
4 valence
8 valence
electrons
3 valence
electrons
electrons
1 valence
electron
2 valence
electrons
Electrons in the
outermost level
are called valence
electrons.
Element Families
Group 1) Alkali Metals (I A)
- highly reactive, especially with water
- 1 valence e- loses valence e- become 1+ ions
Li, Na, K, Rb, Cs, Fr
Group 2) Alkaline Earth Metals (II A)
- very reactive but less than group 1
- 2 valence e- lose valence e-’s
- become 2+ ions
Be, Mg, Ca, Sr, Ba, Ra
Groups 3-12) Transition Metals (B)
- most have 2 valence e-, some
with 1 or more
- all lose valence e- several become 2+ ions
3
Sc
Y
Lu
Lr
4
5
6
7
Ti V Cr Mn
Zr Nb Mo Tc
Hf Ta W Re
Rf Db Sg Bh
8
Fe
Ru
Os
Hs
9
10
11
12
Co Ni Cu Zn
Rh Pd Ag Cd
Ir Pt Au Hg
Mt
Group 17) Halogens (VII A)
- highly reactive
- form cmpds called halides
- fluorine most reactive element
- 7 valence e- Gain 1 e- become 1- ions
F, Cl, Br, I, At
Group 18) Noble Gases (VIII A)
- not reactive (inert)
- cmpds formed only under special
conditions
- full outer energy level (8 valence e-)
except He, 2 valence e-
He, Ne, Ar, Kr, Xe, Rn
Other Groups/Families
Group 13: 3 valence e14: 4 valence e15: 5 valence e16: 6 valence e-
(IIIA)
(IVA)
(V A)
(VI A)
Periodic Trends
Atomic Radius
INCREASE
I
N
C
R
E
A
S
E
S
Atomic Radii
Ionization Energy
Periodic Trends
Ionization Energy
INCREASES
I
N
C
R
E
A
S
E
S
Ionization Energy
Periodic Trends
Electronegativity
INCREASES
I
N
C
R
E
A
S
E
S
O
M
I
T
Electronegativity
Ion Radius