Name ____________________________________
Period ____________
6-1 Development of the Periodic Table
A) The early periodic table
1) By the end of the 1700’s scientists had identified only 30 elements
2) By the mid 1800’s about 65 elements had been identified using spectra photography and line
spectra
3) Their where so many individual elements with slightly different chemical and
4)
physical properties that it became hard to keep track of all of them.
Chemists began to need a organization system to help keep tack of all these similar
but slightly different elements
a) This organization system would ideally group the elements in a way that described there
chemical and physical properties
B) Dmitri Mendeleev and the first periodic table
1) Dmitri Mendeleev – Organized the 1st periodic table according to increasing
atomic mass
a) Mendeleev put elements with similar chemical and physical
properties
in the same vertical column.
b) Group- a vertical column of elements on Mendeleev periodic table that have similar chemical and
physical properties
2) Mendeleev noticed that when elements where arranged according to atomic mass some elements don’t
fit into the predicted group. Because of this Mendeleev arranged some elements out of order and put
them in the group that best matched their chemical properties.
3) He also left three empty spaces in his table and used his groups to correctly
predicted the properties of these 3
unidentified elements.
C) Moseley and the periodic law
1) Moseley reorganized Mendeleev’s periodic table the periodic table by atomic number instead of
atomic mass
2) When the periodic table was reorganized in this way it was found that all the elements fell into the
correct group without the need to reorganize
3) The Periodic Law - When elements are arranged in order of increasing atomic
number, their physical and chemical properties show a predictable pattern.
6-2 Reading the Periodic Table
A) What is the periodic table of the elements?
1) The periodic table of the elements is a chart that lists all the elements that have ever existed in a meaningful
way.
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2) The elements square on the table contains information unique to that element like atomic number, atomic
symbol, name of the element and average atomic mass of the element
3) The location of the elements square on the periodic table tells how that element relates to other elements in
terms of its chemical and physical properties
a) Roughly speaking elements the closer two elements are to each other the more similar their chemical and
physical properties
The elements square on the table contains information unique to that element:
13
Al
Aluminum
26.9815
B) How are elements squares organized on the periodic table?
1) Groups or Families – The vertical columns on the periodic table
a) Elements in the same groups have similar chemical properties because these elements have the same
number of valance electrons which are the electrons involved in bonding
b) Because groups or families have similar chemical properties some have been given special names
(I) Alkali metals – elements in group 1 of the periodic table that react with water to make
alkaline (basic solutions)
(II) Alkaline earth metals - Elements in group 2 of the periodic table that react with water to
make alkaline (basic solutions) and are common in the earths crust
(III) Halogens – Elements in group 7 of the periodic table that react with most metals to
produce salt
(i) Halogen is Greek for “salt maker”
(IV) Nobel gas – Elements in group 8 of the periodic table that have a filled valance shell and
so they don’t react with any element
(i) Like nobility they don’t mix with any of the “common” elements
Elements in the same groups have similar chemical properties because these elements have the same number of
valance electrons
1e
2e
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3e
4e
5e
6e
7e
Full
Valance
shell
Group names of elements
Alkali
Alkali Earth
Metals Metals
Transition Metals
Carbon
Family
Nitrogen Oxygen Halogens Nobel
Family
Family
Gases
C) Are there different types of elements?
1) An element can be classified as one of three basic types, Metals, Nonmetals, and
Metalloids or Semimetals
2) In general metals occupy the left side of the periodic table, nonmetals are on the right side of the
periodic table, and metalloids separate them in a “magical stairway shape”
The periodic table separates elements into regions of metals non metals and metalloids
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3) Metals:
a) Physical properties of metals:
(I) Luster- metals are shiny, they reflect light
(II) Metals are good
conductors of heat and electricity
(III) Metals have a high density (metals are heavy for their volume)
(IV) Metals have a high melting point
(V) Malleable - metals can be shaped or formed by hammering or pressure
b) Chemical Properties of Metals:
(I) Metals Easily lose electrons in chemical reactions
(II) Metals corrode easily (Example: silver tarnishing and iron rusting)
4) Nonmetals:
a) Physical properties of nonmetals:
(I) Nonmetals have no luster or a dull appearance
(II) Nonmetals are poor
conductor of heat and electricity
(III) Nonmetals have a low density (light for their volume)
(IV) Nonmetals have a low melting point
(V) Nonmetals are brittle (they break or shatter easily)
b) Chemical Properties of Nonmetals:
(I) Nonmetals tend to gain electrons in chemical reactions
(II) Nonmetals tend not to corrode
5) Metalloids:
a) Physical Properties of Metalloids:
(I) Metalloids can be shiny or dull
(II) Metalloids conduct heat and electricity better than nonmetals but not as well as metals
(III) Metalloids can be dense or light weight
(IV) Metalloids have a melting point between metals and non metals
(V) Metalloids can be malleable or brittle
6-3 Trends in the Periodic Table
A) What can the periodic table tell us about an elements physical and chemical characteristics?
1) As you scan from left to right on the periodic table numerous physical and chemical characteristics
become described in trends
a) There are 5 main atomic trends described by the periodic table:
(I) Atomic radius
(II) Ionization
energy (successive ionization energies)
(III) Electronegativity
B) How does the periodic table describe an elements atomic radius?
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1) Atomic radius - The distance from the nucleus of an atom and its valance
electrons
a) This is a very important trend because as electrons get farther and farther away from the
nucleus of an atom the atom has a harder time holding on to them
(I) Therefore, in general the larger the atomic radius the more reactive an element is
b) Atoms get larger going down a group and smaller going
across
a period.
(I) Atoms get larger moving down a period because electrons are being added to energy levels
farther from the nucleus of an atom
(II) Atoms get smaller moving across a period because the electrons are adding to the same energy
level
Atomic Radius Trends on the Periodic Table
Distance of electrons from the nucleus matters a lot more in atomic radius than does number of protons and
electrons. Just think of what happens when you take two oppositely charged magnets and slowly bring them
together (as the distance between the magnets decreases their attraction goes way up). As you move across a
period electrons are added to the same energy level (same distance away from the nucleus) and so the additional
electrons are just attracted more by the increasing number of protons in the nucleus. As you go down a group
on the periodic table electrons are added to energy levels farther away from the nucleus and so the nucleus has
less ability to attract them and the radius gets larger.
C) How does the periodic table describe oxidation and reduction?
1) Oxidation – The process of loosing electrons
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2) Reduction – The process of gaining
electrons
3) The octet rule - An atom will tend to bond, gaining or loosing electrons in order to acquire a
full
set of valence
electrons
(noble gas electron configuration).
a) Metals tend to oxidize or loose electrons to obtain their noble
gas electron
configuration
b) Nonmetals tend to reduce or gain electrons to obtain their noble
gas electron
configuration
c) Since most of the most common and stable elements involved in life occur in period 2 of the periodic
table, a “full valance shell” means 8 electrons
(I) In reality this is the only period of the periodic table that has 8 electrons in its valance shell so it
should really be called the octet anomaly
(II) “Octet” = 8 electrons = s2p6 valance electron shell configuration
Trends for Oxidation and Reduction on the Periodic Table
Loose
1e-
Loose
2e-
Loose
3eTransition Metals
Don’t Apply
+
+
1
2
Charge Charge
Gain
3e-
Gain
2e-
Gain
1eNoble
Gas
Depends
+
3
Charge
-
3
Charge
-
2
1
Charge Charge
D) How does the periodic table describe Ionization Energy?
1) Ionization energy - The energy need to remove one electron from an atom.
a) Elements that do not want to lose their electrons (non metals) have high
2)
ionization energies.
b) Elements that easily lose their electrons (metals) have low ionization
energies.
Ionization energy decreases as you move down a group because the elements
electrons farther away from the nucleus and thus not being held onto as tight.
3) Ionization energy increases as you move across a period because the elements
electrons are closer to the nucleus and thus held onto more tightly
a) The trend for ionization energy is opposite that of atomic radius
b) This isn’t a pure trend because atoms with completely filled orbitals tend to hold onto electrons
slightly tighter those with incompletely filled orbitals
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4) Successive Ionization Energies – Energy required remove electrons beyond
the 1st
electron.
a) Ionization energies will increase for every electron removed,
because the atom becomes more and more positive and thus can hold onto its electrons more and
more tightly
Ionization Energy Trends on the Periodic Table
In general ionization energy increases moving across a period and decreases moving down a group
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More specifically, atoms with completely filled or evenly filled orbitals are more stable and it therefore takes
more energy to remove their electrons than other atoms. (This part is an just for your information, just know the
general trend)
E) What is electronegativity?
1) Electronegativity - Reflects an atom’s ability to gain electrons in a chemical bond.
a) Since non metals tend to reduce, they tend to be more electronegative
b) Since metals tend to oxidize they tend to be less electronegative
c) Electronegativity of an element is rated on a scale from 0 to 4, the higher the
number the more electronegative the element tends to be (the more it
wants an electron to fill its outer shell)
d)
Electronegativity decreases as you go down a group,
because the atoms radius is so large that the nucleus cant get close enough to electrons to attract
them effectively
e) Electronegativity increases moving across a period,
because the atoms radius becomes smaller and therefore can effectively attract electrons
(I) The trend for electronegativity is opposite that of atomic radius
Electronegativity Trends on the Periodic Table
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