Pre-class Activity
How are library books classified?
Why is such a classification system valuable?
History of the Periodic Table
John Newlands (1864)Recognized that when
atoms are arranged by increasing mass, their properties repeated every eighth element which he named the “law of octaves”
Elements with similar properties were arranged in the same row
Did not work for all known elements
Dimitri Mendeleev (1869)Organized the first
periodic tableArranged elements by
increasing atomic massWas able to predict the
existence and properties of yet undiscovered elements
Modern Day Periodic Table
Henry Moseley
o Arranged elements according to increasing atomic number instead of increasing atomic mass
o Demonstrated a periodic repetition of chemical and physical properties called the periodic law
Organization of the Periodic Table
Group
Period
Questions
What is the location, by group and period, of Boron?
Group 13 Period 2
Which element is found in group 9, period 5?
Rhodium
Main Group or Representative Group Elements
s-blockp-block
1A
2A 3A 7A6A5A4A
8A
Transition Elements
d-block
f-block
Metals, Metalloids, and Nonmetals
Metalloids
Metals
Inner Transition Metals
Transition Metals
Alkali M
etal
sAlka
line
Earth
Met
als
Oth
er M
etal
s
Properties of Metals
Shiny
Smooth
Solid at room temp
Malleable
Ductible
Conduct Electricity
Metalloids (Semimetals)
13 14 15 16 17
BBoron
CCarbon
NNitrogen
OOxygen
FFluorine
AlAluminium
SiSilicon
PPhosphorus
SSulfur
ClChlorine
GaGallium
GeGermanium
AsArsenic
SeSelenium
BrBromine
InIndium
SnTin
SbAntimony
TeTellurium
IIodine
TlThallium
PbLead
BiBismuth
PoPolonium
AtAstatine
Metalloids contain physical and chemical properties of both metals and non-metals
Nonmetals
Hal
ogen
sN
oble
Gas
es
Nonmetals are generally gases or brittle, dull-looking solids. They are poor conductors of electricity.
Valence Electrons
For the Representative Elements, the group number corresponds to the number of valence electrons of atoms in that group.
classification of Elements
1
7
2
6
3
5
4
5
6
34
5
4
s block p block
d block
f block
Questions
How many valence electrons does Antimony (Sb) have? What is it’s Lewis Dot structure?
5 Sb
Which element is represented by the following electron configuration?
[Xe] 6s24f143d8
Platinum (Pt)
Periodic Trends in Atomic Radii
From one group to the next, atomic radius decreases because the the electrostatic attraction between increasingly larger nuclei increases, pulling the electrons closer to the nucleus
Decreases
Increases
From one row to the next, atomic radius increases because increasing numbers of neutrons shield the electrostatic force and valence electrons are located further and further away from the nucleus
Periodic Trends in Ionic Radii
Decreases
Decreases
Increases
From one row to the next, atomic radius increases because increasing numbers of neutrons shield the electrostatic force and valence electrons are located further and further away from the nucleus
For positive ions, charge numbers increase as more electrons are lost from the atom. The electrostatic force is greater for smaller numbers of electrons which decreases the ionic radius.
For negative ions, as the charge number increases, so does the number of electrons. Electrostatic forces decrease and the ionic radius increases in size.
Periodic Trends in Ionization Energy
Increased nuclear charge that occurs from one group to the next accounts for electrons being held more tightly within the atom. The more tightly they are held, the greater the amount of energy that is required to remove and electron from an atom.
The amount of energy required to remove an electron from an atom
Increase
Decrease
From one row to the next, ionization energy increases because increasing numbers of neutrons shield the electrostatic force and valence electrons are located further and further away from the nucleus
Periodic Trends in ElectronegativityAbility of an atom to attract electrons
Increase
Decrease
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