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The Periodic Table and the Elements
A. Development of the Periodic Table
1. During the 19th century (when most of the elements were
discovered), many chemists tried to classify the elements
according to their _____________________
** Late 1790's.....Antoine Lavoisier compiled a list of
23 known elements
2. Johann Dobereiner (German chemist -- 1780-1849)
a) Triads of Elements....noted that atomic mass seemed
to be related to __________________________
b) Examples: (1817)
Calcium -- 40.1 Chlorine -- 35.5 Sulfur -- 32.1
Strontium -- 87.6 Bromine -- 79.9 Selenium -- 79.0
Barium -- 137.3 Iodine -- 126.9 Tellurium -- 127.6
3. John Newlands (English chemist -- 1837-1898)
** By 1870.....70 known elements!
a) ________________....every 8th element was similar to the one
above it....forced elements into groups where they
didn’t belong (Noble gases not discovered yet)
b) Example: (1864)
1
2
3
4
5
6
Li
Be
B
C
N
O
Na
Mg
Al
Si
P
S
K etc.
4. Julius Lothar Meyer (German chemist -- 1830-1895)
a) developed this idea further by stating that there was a
________________________ in the properties of the known
elements when they were arranged in order of their
_____________________ (1872)
7
F
Cl
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5. Dmitri Mendeleev (Russian chemist -- 1834-1907)
a) suggested periods (horizontal rows) of varying lengths
based on _____________________
b) left empty spaces for elements undiscovered AND
________________ properties for six of these
c) published his work in 1871 (one year ahead of Meyer)
d) his predictions made his proposal seem superior to Meyer’s
and is today, given credit for developing the first
Periodic Table
** predicted elements:
Ekaboron .... Scandium (21)
Ekaaluminum .... Gallium (31)
Ekasilicon .... Germanium (32)
Ekamanganese .... Technetium (43)
Dvimanganese .... Rhenium (75)
Ekatantalum .... Polonium (84)
e) original Periodic Law =
f) in his table...the elements were placed in horizontal rows
so that elements with similar properties fell into the
same vertical columns....called _______________
g) there were a few __________________ in his chart (3 total)
** Iodine & Tellurium
** he simply discarded these!
5. Henry Moseley (English chemist -- 1887-1915)
a) 1914....performed experiments that revealed the __________
_____________ of several elements and suggested that the
elements in Mendeleev’s table be arranged in order of
increasing atomic number instead of atomic mass
b) modern Periodic Law =
c) eliminated the irregularities!!
d) he was killed in WWI...Britain adopted a policy that does
not place a scientist in battle
6. Today.....Electron Configuration determines properties
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B. Reading the Periodic Table
1. Information provided within the P.T.
a) name of element; symbol; atomic number; atomic mass
b) horizontal rows = ________________ (7)
c) vertical columns = _______________________ (18)
** members of a group have __________________________
** have the same general electron configuration
2. Periods
a) period # identifies _______________________
b) ___________ periods = periods 1,2,3
** relatively common in Earth’s crust, ocean & atmosphere
** contain only s and p electrons
c) ___________ periods = periods 4,5
** 18 elements each
** _____________________ occurs
d) ____________ elements = elements with incomplete subshells
** groups 3-12
** many irregularities in e- configurations
** see pp. 116-117
** period 6 places electrons in the 4f sublevel
** period 7 is incomplete
e) _________________ Series (#57-71)
** 4f sublevel
** valence shell = PEL 6
f) _________________ Series (#89-103)
** 5f sublevel
** valence shell - PEL 7
** all are radioactive! (last natural element...Uranium)
** both series are shown out of the main body of the P.T.
* taken out by Glen Seaborg in 1944
** unlikely that period 7 will ever be completed....the
elements are too unstable and expensive to make
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3. Groups
a) properties of elements in groups are related directly to
__________________________
b) Alkali Metals
** group 1
** s1
c) Alkaline Earth Metals
** group 2
** s2
d) Halogens
** group 17
** s2 p5
e) Noble Gases
** group 18
** stable octet of electrons
** Kr and Xe can be forced into compound form
f) Starting with an element in Group 1 and moving to the right,
active metallic elements are followed by less active ones....
these are followed by increasingly active nonmetallic
elements eventually ending with a noble gas
C. Periodic Trends
1. Properties of the elements exist that allows them to be placed in
their horizontal periods and vertical groups.....NOTE: the
elements do not have the properties described because of their
positions...rather, both the position and properties arise from
the electron configurations of the atoms!!
2. Coulombic Attraction =
a) examples:
** __________________________
** __________________________
** __________________________
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3. Number of Electrons Present
a) examples:
** _____________________
** _____________________
D. Ionization Energy
1. Definition =
a) aka: __________________________
b) produces a cation
2. equation: A(g) + energy  A+(g) + 1eGas phase of
any element
Ionization
Energy
Gas phase of the
cation produced
Electron that
was separated
ex. Li (g) + 520 kJ/mol  Li+(g) + 1e3. 1st ionization energy = removal of the 1st electron;
2nd ionization energy = removal of the 2nd electron; etc.
** more energy is needed for each separation because of
an increasingly greater net positive charge
** Table 6-2 p.168 Successive I.E. for Period 2 Elements
4. Trends.....
a) I.E. ______________ across a period.....
** WHY?....(1)more electrons are involved thus more
energy is required to remove them and; (2)more protons
(larger positive charge) pull on the electrons -results in a greater __________________________
b) I.E. ______________ down a group.....
** WHY?....(1)more PEL’s are added causing a greater
distance between the nucleus and the valence shell -coulombic attraction decreases and; (2) there is a
______________________ caused by the repulsion between
kernel electrons and valence electrons
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E. Electronegativity
1. Definition =
2. Values range from 0.7 for metals in Group 1 to a high of 4.0 for
fluorine in Group 17 (Figure 6-18 p.169)
a) these values are expressed in terms of a relative scale with
arbitrarily selected standard units (called Paulings....
named after the American scientist Linus Pauling)
3. Trends.....
a) Electroneg. ____________ across a period.....
** WHY?....(1) more electrons are involved and the
tendency is to attract electrons rather than lose them and;
(2) more protons (larger positive charge) pull on the
electrons -- results in a ___________ coulombic attraction
b) Electroneg. ____________ down a group.....
** WHY?....(1)more PEL’s are added causing a greater
distance between the nucleus and the valence shell -coulombic attraction decreases and; (2) there is a
shielding effect caused by the repulsion between kernel
electrons and valence electrons
4. The Noble Gases are typically excluded due to _____________ and
lack of significant numbers of compounds formed with them.
F. Electron Affinity
1. Definition =
2. Electron affinity can have either a positive or negative numerical
value
a) negative values = energy is ____________ when an electron is
gained (these indicate that it is easier for an element to
gain electrons)
b) positive values = energy must be _________ to the atom for it
to gain an electron (these indicate that it is much more
difficult for an atom to gain electrons....they would rather
lose them)
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2. Trends.....
a) E.A. values generally become _____________ across a period....
** WHY?....(1) nuclear charge increases; (2) atomic radius
decreases and; (3) the shielding effect is constant
** results in an increased attractive force between the
nucleus and electrons
b) E.A. values generally become _____________ down a group....
** WHY?....(1) nuclear charge increases; (2) atomic radius
increases and; (3) the shielding effect increases due to the
increased distance between the nucleus and valence shell
G. Atomic Radius
1. Definitions:
(1) the distance from the ________________ to the approximate
edge of its ___________________
(2) the closest distance to which one atom will approach
another atom of any size under certain specified
conditions
(3) 2 the distance from center to center of two like atoms
2. Trends..... Figure 6-11 p.163
a) A.R. _______________ across a period.....
**WHY?....(1) as atomic number increases, there are more
protons to attract the valence electrons C coulombic
attraction increases
b) A.R. _______________ down a group.....
**WHY?....(1) more PEL’s are added causing a greater
distance between the nucleus and the valence shell -coulombic attraction decreases and; (2) the shielding effect
increases due to the increased distance between
the nucleus and valence shell
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H. Ionic Radius
1. Definition =
** effective -- remember that ions, like atoms, have an
electron cloud....no edge!
2. Ions =
a) cation = ion with a ____________________ (lost electrons)
** metallic elements (ex. sodium Na+1, iron Fe+2)
b) anion = ion with a ____________________ (gained electrons)
** nonmetallic elements (ex. sulfur S-2 , chlorine Cl-1)
3. The ionic radius of an atom may be larger or smaller than its
atomic radius -- it depends on the chemical nature of the
element (do they gain/lose electrons?)
a) metallic elements -- _____ ionic radius/_____ atomic radius
** they lose electrons
b) nonmetallic elements C large ionic radius/small atomic radius
** they gain electrons
4. Trends..... Figure 6-14 p.166
a) I.R. gradually ____________ through the metals and suddenly
increases with the first nonmetals, then gradually
decreases again across a period.....
** WHY?....as atomic number increases, there are _______
protons to attract the valence electrons -- coulombic
attraction increases -- the sudden increase occurs with the
first nonmetals because they are gaining electrons
b) I.R. _____________ down a group.....
** WHY?....(1) more PEL’s are added causing a greater
distance between the nucleus and the valence shell -coulombic attraction decreases and; (2) the shielding effect
increases due to the increased distance between
the nucleus and valence shell
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I. The Elements
1. Properties of s-Block elements
a) __________________ elements = the elements found in
groups 1 & 2 and 13 - 18
** they display a wide range of physical and chemical
properties
** include metals and nonmetals; highly reactive elements
and some that hardly react at all; and elements that
are solids, liquids, and gases at room temp.
** elements in the same group have the ________________
______________________
b) General properties of metals (ex. Groups 1 & 2)
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
c) The degree of reactivity in a metal is the result
of two factors:
(1) the __________________________ in the nucleus
** moving from left to right in a period...
positive charge _________________
** metals on the left have a _______________ hold on
valence electrons than metals on the right
(2) the _______________________________
** metals whose atoms have fewer valence electrons
to lose are _____________________
** the most active metals are found at the beginning
of each period toward the _______ of their groups
** ex. Sodium is more active than Magnesium
Cesium is more active than Sodium
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d) Nuclear charge and atomic size also combine to affect the
properties of metallic elements within a group
(1) metallic character ___________________________
(2) Group 1 is made up of the most active metals.....
due to their large size and small nuclear charge
e) General properties of nonmetals (ex. Groups 13-17)
a)
b)
c)
d)
e)
f)
g)
f) Left to right across a period, nonmetallic character __________
whereas down a group, it _______________
g) Properties of semimetals
(1) border the metals and nonmetals along a stair-step line
(2) B Si As Te At Ge Sb
(3) aka: ____________________
(4) useful _______________________
h) Alkali Metals...Group 1
(1) react with water to form ___________________
(2) have one valence electron
i) Alkaline Earth Metals...Group 2
(1) react with oxygen to produce oxides (called earths
by early chemists) which when exposed to water
produced alkaline solutions (except Be)
(2) have two valence electrons
2. Properties of p-Block Elements...Groups 13-18
** metals, metalloids and nonmetals are all found in these
groups
** have a greater range of properties and may form more
than one type of ion (due to electron configuration)
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a) Boron Group
** first four elements form +3 ions
** thallium only loses it’s p electron
b) Carbon Group
** few rules apply to this group
** contains one nonmetal (C); two metalloids (Si, Ge) and
two metals (Sn, Pb)
c) Nitrogen Group
** contains two nonmetals (N & P); two metalloids
(As & Sb) and one metal (Bi)
d) Oxygen Group
** contains two nonmetals (O & S); two metalloids
(Se & Te); and one metal (Po..radioactive)
** form -2 anion
e) Halogens
** have the ability to form ________ with almost all metals
** have 7 valence electrons.....form -1 anion
f) Noble Gases
** among the last natural elements to be discovered
** colorless and unreactive
** all (except He) form a ____________ of valence electrons
** no known compounds of He, Ne, or Ar
3. Properties of d-Block and f-Block Elements
a) Transition Metals
** include Groups 3-12/Periods 4-7
** these elements place their final electrons in a d or f
sublevel
** d-Block elements are called ____________________ while
f-Block elements are called ________________________
** most transition metals are hard solids with high MP
and BP.....the more unpaired electrons, the greater
the hardness and higher the MP/BP
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b) Lanthanide Series
** period 6 inner transition metals
** silvery metals with high MP
** usually found mixed together in nature and are
extremely hard to separate
c) Actinide Series
** period 7 inner transition metals
** 3 are natural.....the rest synthetic.....all are ____________
J. Creating the Elements
1. Natural vs. Synthetic elements
a) natural elements = occur naturally in Earth’s crust, water,
and atmosphere (up to #92; except Fr Pr Tc At)
b) synthetic elements = _____________________
2. Nuclear Fusion =
a) occurs naturally in stars and hydrogen bombs
b) in our sun.....4 Hydrogen nuclei fuse to produce 1 Helium
nucleus.....there is more mass before the reaction than
what is produced as a result of the reaction....the rest is
converted to __________________
c) this process also produces elements _________ than Hydrogen
** He + He  Be (+ energy)
He + Be  C (+ energy)
3. Artificial Isotopes =
(such as protons;
neutrons; alpha =+-charged He nuclei; beta = fast-moving e-)
a) these particles are called ____________________
b) produces isotopes of naturally-occurring elements as well as
isotopes of synthetic elements
c) the speed required for the nuclear reactions needed to
produce these isotopes is produced in particle
accelerators