JOURNAL 10/26

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JOURNAL 10/26

• Which has the largest atomic number? K, Na, or P
• Which has the largest atomic radius?- Ca, Sr, Ba

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The Periodic Table and Periodicity
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A. Dmitri Mendeleev

• Dmitri Mendeleev (1869, Russian)

• Organized elements by increasing atomic mass.
• Predicted the existence of undiscovered elements.

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B. Henry Mosely

• Henry Mosely (1913, British)

• Organized elements by increasing atomic number.
• Fixed problems in Mendeleevs arrangement.

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A. Terms

• Periodic Law

• Properties of elements repeat periodically when
  the elements are arranged by increasing atomic
  number.

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Arrangement

• In order of increasing atomic number in specific
  columns and rows.

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Groups- vertical columns of the PT
The Periodic Table The Periodic Table The Periodic Table The Periodic Table The Periodic Table The Periodic Table The Periodic Table
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
1    
2                
3                
4                                    
5                                    
6                                    
7                                    

                           
                           
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Periods- horizontal row on the PT
The Periodic Table The Periodic Table The Periodic Table The Periodic Table The Periodic Table The Periodic Table The Periodic Table
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
1    
2                
3                
4                                    
5                                    
6                                    
7                                    

                           
                           
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Groups are important on the PT

• Why?
• The elements in a group have similar chemical and
  physical properties!

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Alkali Metals Group 1
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
1 H  
2 Li              
3 Na              
4 K                                  
5 Rb                                  
6 Cs                                  
7 Fr                                  

                           
                           
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Alkaline Earth Metals Group 2
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
1    
2   Be            
3   Mg            
4   Ca                                
5   Sr                                
6   Ba                                
7   Ra                                

                           
                           
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Halogens Group 17
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
1    
2             F  
3             Cl  
4                                 Br  
5                                 I  
6                                 At  
7                                    

                           
                           
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Noble Gases Group 18
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
1   He
2               Ne
3               Ar
4                                   Kr
5                                   Xe
6                                   Rn
7                                    

                           
                           
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Transition Metals Groups 3 - 12
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
1    
2                
3                
4                                    
5                                    
6                                    
7                                    

                           
                           
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Inner Transition Metals
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
1    
2                
3                
4                                    
5                                    
6                                    
7                                    

La                         Yb
Ac                         No
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Metals on the PT
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
1    
2                
3                
4                                    
5                                    
6                                    
7                                    

                           
                           
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Metals

• Metals are lustrous (shiny), malleable, ductile,
  and are good conductors of heat and electricity.
• They are mostly solids at room temp.
• What is one exception?

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Nonmetals - Lack properties of metals
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
1    
2                
3                
4                                    
5                                    
6                                    
7                              

                           
                           
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Nonmetals

• Nonmetals are the opposite.
• They are dull, brittle, nonconductors
  (insulators).
• Some are solid, but many are gases, and Bromine
  is a liquid.

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Metalloids (semi-metals)- have a mixture of
metallic and nonmetallic properties
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
1    
2                
3       Si        
4                           Ge As      
5                             Sb Te    
6                               Po At  
7                              

                           
                           
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Metalloids

• Metalloids, aka semi-metals are just that.
• They have characteristics of both metals and
  nonmetals.
• They are shiny but brittle.
• And they are semiconductors.
• What is our most important semiconductor?

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BOILING POINT MELTING POINT VS. ATOMIC NUMBER
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Diatomic Elements

• Most elements can be isolated to atomic elements
  individual atoms
• 7 elements are too reactive to exist as
  individual atoms, instead, they are found as
  molecular elements 2 atoms bonded together

• Hydrogen, H2
• Oxygen, O2
• Nitrogen, N2
• Chlorine, Cl2
• Bromine, Br2
• Iodine, I2
• Fluorine, F2

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Trends

• Atomic radii Ionic radii
• Increase down a group
• Why? greater shielding
• Decrease across a period
• Why? Greater effective nuclear charge

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Atomic Radii

• one-half the distance between the nuclei of
  identical atoms that are bonded together.

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1. Atomic Size - Group trends
H

• As we increase the atomic number (or go down a
  group). . .
• each atom has another energy level,
• so the atoms get bigger.

Li
Na
K
Rb
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1. Atomic Size - Period Trends

• Going from left to right across a period, the
  size gets smaller.
• Electrons are in the same energy level.
• But, there is more nuclear charge.
• Outermost electrons are pulled closer.

Na
Mg
Al
Si
P
S
Cl
Ar
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Atomic Size Decreases left to right

• Why? As you move across a period, the atom gains
  electrons as well as protons. Because the
• effective nuclear charge has increased, the
  electrons will therefore be pulled closer to the
• nucleus, causing the atom to become smaller.

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• Atomic Size (radius)

• Size tends to increase down a column.
• Size tends to decrease across a row.

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B. Periodic Trends

• Atomic Radius

• Increases to the LEFT and DOWN.

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K
Period 2
Na
Li
Atomic Radius (pm)
Kr
Ar
Ne
H
Atomic Number
10
3
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Ionic Radii the size of an ion.

• Cation a positive ionNa,Mg2,Fe2, Fe3,
• Formed by the loss of an electron
• Cations are smaller than their neutral atom.
• As an electron is lost, the effective nuclear
  charge is greater, causing the electron cloud to
  become pulled closer to the nucleus, making it
  smaller

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• Anion a negative ion Cl-, F-, N3-,
• Formed by the gain of an electron(s).
• As an electron is added, the nucleus remains
  the same so the electrons are not drawn as close
  to the nucleus. Also, added electron causes
  repulsion among other electrons.

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Ion Group trends

• Each step down a group is adding an energy level
• Ions therefore get bigger as you go down, because
  of the additional energy level.

Li1
Na1
K1
Rb1
Cs1
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Ion Period Trends

• Across the period from left to right, the nuclear
  charge increases - so they get smaller.
• Notice the energy level changes between anions
  and cations.

N3-
O2-
F1-
B3
Li1
Be2
C4
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Atomic size and Ionic size increase in these
directions
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Trends

• Ionization energy Electronegativity
• Decrease down a group
• Why? Greater shielding
• Increase across a period
• Why? Greater effective nuclear charge

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Ionization Energy

• Energy required to remove one electron
• from an atom
• Ion an atom or group of bonded atoms
• that has a positive or negative charge.
• Ex. Na, Cl-, O2-, Fe3, NH4, CO32-,
• Monatomic ion ion containing one atom
• Polyatomic ion ion containing atoms bonded
  together

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Ionization Energy
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• Noble Gases have the highest ionization
• energies because they have a full octet
• Group IA have the lowest ionization
• Energies
• Decreases down a group because electrons in
  higher energy levels are easier to remove
• Increases across period because more electrons
  in an energy level make it more difficult to get
  to the magic number of 8

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Electronegativity

• a measure of the ability of an atom in a
• chemical compound to attract electrons
• In a chemical compound, the more
• electronegative atom will attract electrons
• more
• Ex. HCl H-Cl electrons are pulled closer to
  Cl

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• The most electronegative atom on the
• Periodic Table is Fluorine
• Electronegativity tends to increase across a
  period
• Electronegativity tends to decrease down agroup

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