Download Periodic Table notes.notebook

Periodic Table notes.notebook
February 08, 2016
History of the Periodic Table
Early Classification
Mendeleev’s Periodic Table: (1869) Arranged elements in a
table by atomic mass. Elements with similar properties
were grouped in columns. Mendeleev left empty spaces
for elements that were “undiscovered”. He used his
table to predict the properties of these elements (Sc, Ga,
Ge) and he was right!
Why did some elements (Ar & K, Co & Ni, I & Te) not
follow the atomic mass pattern?
Why were the properties periodic?
Feb 8­8:53 AM
The Modern Periodic Table
Moseley’s Atomic Number: (1911) led to
the arrangement of the periodic table by
increasing atomic number; retained
columns with similar properties
Modern Periodic Law: The properties of
the elements are periodic functions of
their atomic numbers
Feb 8­8:56 AM
Periodic Table notes.notebook
February 08, 2016
Arrangement of the Modern Periodic Table
Physical Property: a characteristic of a
substance that can be observed or measured
without changing the identity of the substance
Chemical Property: a description of a
substance’s ability to react (or not react).
Changes into a new substance as a result of the
observation or measurement.
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General Properties of the Elements
Metals: left of the staircase and Al
Good conductors of heat and electricity, malleable,
ductile, shiny, high melting points, mostly solids (Hg is
the exception), few valence e‐
Nonmetals: right of the staircase and H
Poor conductors of heat and electricity, are gases or
dull, brittle solids, low melting points, 5‐7 valence e‐
Metalloids (semimetals): touching the staircase except Al
Solids, have some properties of metals and nonmetals,
semiconductors
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Periodic Table notes.notebook
February 08, 2016
Families or Groups (columns)
Main Group Elements (s & p blocks)
Alkali Metals – Group I
most reactive metals, not found free in nature, silvery, soft, react
vigorously with H2O, lose e‐ in reactions, general valence structure ns1,
general dot diagram 
Alkaline Earth Metals – Group 2
reactive, not found free in nature, harder, denser, stronger than Group I,
lose e‐ in reactions, general valence structure ns2, general dot diagram 
Halogens – Group 17
most reactive nonmetals, “salt formers”, gases (F, Cl), liquid (Br), solids (I,
At), gain e‐ in reactions, general valence structure ns2np5, general dot
diagram
Noble Gases – Group 18
stable, unreactive elements (although some can form compounds),
discovered between 1894‐1900, general valence structure ns2np6, general
dot diagram, He is the exception
Feb 8­8:58 AM
Transition elements (d block) – metallic properties, less reactive, harder &
stronger than s‐block, sum of the outer “s” and “d” electrons gives the group
number, variable oxidation numbers (charges), often form colored ions,
deviation in e‐ configurations
Inner Transition Elements or Rare Earth Elements (f block)
Lanthanides (early 1900’s): atomic numbers 58‐71 – shiny metals, reactivity
similar to Group 2
Actinides: atomic numbers 90‐103 – all are radioactive, Th through Np are
naturally occurring, all the rest are synthetic
Hydrogen: unique properties! Physical properties of a gas, chemical properties
of a Group I metal
Feb 8­9:00 AM
Periodic Table notes.notebook
February 08, 2016
Periodic Properties of the Elements: A result of Zeff and
shielding by core electrons
Valence e‐ (outermost energy level, s & p e‐)
Group
1
2
3‐12
13
14
15
16
17
18
e‐ config s1
s2
s2d1‐10
s2p1
s2p2
s2p3
s2p4
s2p5
s2p6
number
of
valence
e‐
2
1,2
‘d’ e‐ can be
lost
3
4
5
6
7
8
varies
(all +)
+3
±4
‐3
‐2
‐1
0
1
oxidation
+1
number
varies
+2
(except He)
Remember: lose e‐ (+); gain e‐ (‐)!
Feb 8­9:01 AM
Atomic Radius: ½ the distance between nuclei of identical atoms
bonded together.
Across a Period: the atomic radius decreases due to nuclear charge
increase (e‐ cloud pulled in tighter to nucleus due to increased
attractive force)
Down a Group: the atomic radius increases due to increase in the
number of energy levels
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Periodic Table notes.notebook
February 08, 2016
Ionic Radius
Cation (+ ion, more p+ than e‐): ionic radius is less than atomic radius
Anion (‐ ion, less p+ than e‐): ionic radius is greater than atomic radius
Across a row: ionic radius goes down due to increasing nuclear charge.
As the first anion in the period is formed, the ionic radius jumps up,
then goes down again as nuclear charge increases.
Down a Group: the ionic radius increases due to increase in the number
of energy levels
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Reactivity
Metals: the most reactive is Fr (largest, easiest to lose e‐)
Metallic Behavior decreases as move across a period,
increases as move down a group
Nonmetals: the most active is F (smallest, hardest to lose e‐)
Nonmetallic Behavior increases as move across a period,
decreases as move down a group
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Periodic Table notes.notebook
February 08, 2016
Ionization Energy (IE): the energy needed to remove one e‐ from the
valence shell of a neutral atom, often called 1st ionization energy,
measured in kJ/mol
Across a Period: ionization energy increases due to nuclear charge
increase, atomic radius decrease, sublevel deviations. Metals
typically have a low IE, nonmetals typically have a high IE.
Down a Group: ionization energy decreases due to increasing energy
level (distance from the nucleus), increasing atomic radius,
shielding
IE increases as each successive e‐ is removed: 3rd IE > 2nd IE > 1st IE;
harder to remove an e‐ from a more (+) ion
Feb 8­9:04 AM
Electronegativity: a measure of the ability of an atom in a
compound to attract e‐ follows same trends as IE
Electron Affinity: the attraction a nonbonded atom has for an
additional e‐ follows same trends as IE
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Periodic Table notes.notebook
February 08, 2016
Summarizing Periodic Trends
Feb 8­9:05 AM
Factors Affecting Periodic Properties
Nuclear Charge (Zeff): affects pull on e‐ cloud; more p+,
more pull (calculated by Protons minus CORE electrons)
Atomic Size: number of energy levels affects the distance
between nucleus and valence e‐; more energy levels,
more distance
Shielding: the number of e‐ between the nucleus and
valence e‐, affects the pull by the nucleus; more e‐, more
shielding, easier to remove valence e‐
Sublevel Stability: ½ and full sublevels are more stable
than other configurations
Feb 8­9:08 AM