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Regents Chemistry: Mr. Palermo
Notes: Unit 4: Periodic Table
MIND BLOWN!!!!
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Key Ideas:
x The placement or location of elements on the Periodic Table gives an indication of physical and chemical properties of that element. The elements on the Periodic Table are arranged in order of increasing atomic number. (3.1y)
x Elements can be classified by their properties and located on the Periodic Table as metals, nonmetals, metalloids (B, Si, Ge, As, Sb, Te), and noble gases. (3.1v)
x Elements can be differentiated by their physical properties. Physical properties of substances, such as density, conductivity, malleability, solubility, and hardness, differ among elements. (3.1w)
x Elements can be differentiated by chemical properties. Chemical properties describe how an element behaves during a chemical reaction. (3.1x)
x Some elements exist in two or more forms in the same phase. These forms differ in their molecular or crystal structure, and hence in their properties. (5.2f)
x For Groups 1, 2, and 13-18 on the Periodic Table, elements within the same group have the same number of valence electrons (helium is an exception) and therefore similar chemical properties. (3.1z)
x The succession of elements within the same group demonstrates characteristic trends: differences in atomic radius, ionic radius, electronegativity, first ionization energy, metallic/nonmetallic properties. (3.1aa)
x The succession of elements across the same period demonstrates characteristic trends: differences in atomic radius, ionic radius, electronegativity, first ionization energy, metallic/nonmetallic properties. (3.1bb)
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UNIT 4: PERIODIC TABLE WWW.MRPALERMO.COM
LESSON 4.1 DEVELOPMENT OF THE PERIODIC TABLE
MENDELEEV
• Organized the elements based upon ATOMIC MASS
MOSLEY
• Developed the Modern Day Table • Organized elements by # of PROTONS
(Atomic Number)
PERIODIC LAW
• The properties of elements are periodic functions of their atomic numbers.
THE RESULT…..
• Can fill in gaps to predict undiscovered elements and their properties
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HOW IS THE TABLE ORGANIZED?
• PERIODS (horizontal rows) - Equal to the # of energy levels (shells)
• GROUPS (vertical columns) - elements have the SAME # of VALENCE
ELECTRONS resulting in similar chemical properties
Period � Group �
• # of period tells us the # of e- SHELLS (AKA principal energy level)
• properties of elements change
drastically ACROSS A PERIOD (metals ! metalloids/semi-metals ! nonmetals)
• # of VALENCE ELECTRONS increases
from left to right (1 ! 8) • Ex: K is in period 4
REACTIVITY OF ELEMENTS
• Determined by # of valence electrons
• All atoms (except Hydrogen) want 8 VALENCE ELECTRONS to become STABLE (full valence shell)
• Called a STABLE OCTET
• The closer to a stable octet the MORE REACTIVE the element is.
****Period 1 elements need 2 electrons to have a full valence shell NOT 8
EXAMPLE:
Which element is in Group 2 and has 4 energy levels?
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EXAMPLE:
• Which two elements have similar chemical properties and why? Na, K, Li, Be
• Na & K are in the same group and have the same number of valence electrons
LESSON 4.2 CATEGORIES & PROPERTIES OF ELEMENTS
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METALS, NONMETALS, METALLOIDS
Li 3
He 2
C 6
N 7
O 8
F 9
Ne
10
Na 11
B 5
Be 4
H 1
Al
13
Si
14
P
15
S
16
Cl
17
Ar
18
K
19
Ca
20
Sc
21
Ti
22
V
23
Cr
24
Mn
25
Fe
26
Co
27
Ni
28
Cu
29
Zn
30
Ga
31
Ge
32
As
33
Se
34
Br
35
Kr
36
Rb
37
Sr
38
Y
39
Zr
40
Nb
41
Mo
42
Tc
43
Ru
44
Rh
45
Pd
46
Ag
47
Cd
48
In
49
Sn
50
Sb
51
Te
52
I
53
Xe
54
Cs
55
Ba
56
He
72
Ta
73
W
74
Re
75
Os
76
Ir
77
Pt
78
Au
79
Hg
80
Tl
81
Pb
82
Bi
83
Po
84
At
85
Rn
86
Fr
87
Ra
88
Rf
104
Db
105
Sg
106
Bh
107
Hs
108
Mt
109
Mg
12
Ce
58
Pr
59
Nd
60
Pm
61
Sm
62
Eu
63
Gd
64
Tb
65
Dy
66
Ho
67
Er
68
Tm
69
Yb
70
Lu
71
Th
90
Pa
91
U
92
Np
93
Pu
94
Am
95
Cm
96
Bk
97
Cf
98
Es
99
Fm
100
Md
101
No
102
Lr
103
La
57
Ac
89
1
2
3
4
5
6
7
�
Ω
METALS
Nonmetals
Metalloids
ELEMENT GROUPS
GROUP 1: ALKALINE METALS
• 1 valence electron • Lose 1 electron to form +1 ions • Extremely reactive with water • Most REACTIVE metal is Fr
GROUP 2: ALKALINE EARTH METALS
• 2 valence electrons • Lose 2 electrons to form +2 ions • Fairly reactive in water
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GROUPS 3-12: TRANSITION METALS
• Least reactive metals • Form COLORED IONS in solution
GROUP 17: HALOGENS
• 7 valence electrons • Gain 1 electron to for -1 ions • Most REACTIVE nonmetal is F
GROUP 18: NOBLE GASES
• Unreactive or INERT • Stable octet (8 valence electrons) - Exception is He which has 2 valence
electrons - monoatomic
HYDROGEN
• Not officially part of a group • Nonmetal • Gas at STP
PROPERTIES OF METALS
• Malleable (can be hammered or rolled into thin sheets)
• Ductile (can be drawn into a wire) • Excellent conductors of heat and electricity • Luster (shiny) • Lose electrons to
form cations • Solid @ STP (except Hg)
METALS HAVE A “SEA” OF MOBILE ELECTRONS….RESULTS IN
ELECTRICAL CONDUCTIVITY
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WHY DO METALS HAVE LUSTER?
• Metals easily absorb light energy which excites the delocalized electrons and when they fall back to lower energy levels they emit light (luster)
WHY ARE METALS MALLEABLE AND DUCTILE?
• Metals consist of layers of atoms that can slide over each other
WHY ARE ALLOYS (MIXTURES OF METALS) STRONGER THAN PURE
METALS?
• Alloys such as brass (a mixture of copper and zinc) are harder than the original metals because the irregularity in the structure helps to stop rows of atoms from slipping over each other
METALLIC CHARACTER
• How much “like a metal” an element is • Franicium is most metallic - Closer to Fr more metallic…further from Fr
least metallic
PROPERTIES OF METALLOIDS
• Semiconductors (Good/moderate conductor)
• Luster (like metals) and Brittle (like nommetals)
• Used for making computer microchips
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PROPERTIES OF NON-METALS
• Poor conductors of heat and electricity
• Brittle (shatter when struck) • Dull • Tend to gain electrons to form anions
SUMMARY OF THE CATEGORIES OF ELEMENTS
LESSON 4.3 TRENDS IN ATOMIC RADIUS
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ATOMIC RADIUS
• SIZE of the atom • Located on Table S
TREND IN ATOMIC RADIUS
ACROSS A PERIOD
• Trend: DECREASES • Why? • Nuclei have greater NUCLEAR PULL
(larger positive charges) which PULL electrons CLOSER
Atomic radius decreases
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13 +
Less nuclear charge Greater nuclear charge
Al
Cl
17 +
DOWN A GROUP
• Trend: INCREASES • Why? • GREATER number of ENERGY SHELLS
(indicated by the PERIOD #)
Ato
mic
Rad
ius
incr
ease
s
USING TABLE “S” TO DETERMINE TRENDS IN ATOMIC RADIUS
TO FIGURE OUT:
• Pick a Period (row) or Group (column) and note the values of the elements
• Example: Going across a period what is the trend in atomic radius?
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• Pick an element on the left side of the periodic table and pick another element on the right side of the same period.
130 pm 60 pm
Trend is decreasing
"
RECALL…..
ION SIZE- METALS
• Ion radius SMALLER than atomic radius
Why? • Metal ions LOSE electrons to form Cations
ION SIZE- NONMETALS
• Ion radius LARGER than atomic radius
• Why? • Nonmetal ions GAIN electrons to for
anions.
© 2002 Prentice-Hall, Inc.
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LESSON 4.4 TRENDS IN IONIZATION
ENERGY & ELECTRONEGATIVITY
RECALL……REACTIVITY Metals
• Decreases across period
• Increases down group
• Reason: The larger the atom the weaker the nuclear pull and the more easily you lose electrons and become stable
Non Metals
• Increases across period
• Decreases down group
• Reason: The smaller the atom the greater the nuclear pull (+) and the more easily it attracts electrons (-)
+
+
e-
e-
Larger atom
Smaller atom
IONIZATION ENERGY
• Energy required to REMOVE the most loosely bound ELECTRON in the valence shell
• Located on Table S
TREND IN IONIZATION ENERGY
• INCREASES across a PERIOD • Why? • Stronger NUCLEAR PULL makes it more
difficult to remove electrons
13 +
Less nuclear charge Greater nuclear charge
Al
Cl
e-
e-
17 +
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TREND IN IONIZATION ENERGY
• DECREASES down a GROUP • Why? • Larger atomic radius means LESS
NUCLEAR PULL on outer electrons
+
e-
+
e-
EXAMPLE
• What is trend in atomic radius going down a group?
• Why does this trend occur?
• 496 • 419 • 403
Trend is decreasing larger atomic radius equals less nuclear pull on valence e-
ELECTRONEGATIVITY
• Measure of the ATTRACTION for electrons • Located on Table S
• FLUORINE most electronegative (4.0) • The closer an atom is to Fluorine the
HIGHER the electronegativity • Scale of 0 - 4
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TREND IN ELECTRONEGATIVITY
• INCREASES across period • Why? - Greater NUCLEAR PULL(charge) to attract
electrons 13 +
Less nuclear charge Greater nuclear charge
Al
Cl
e-
e-
17 +
TREND IN ELECTRONEGATIVITY
• DECREASES down group • Why? - Larger atomic radius means LESS
NUCLEAR PULL to attract electrons to the valence shell
+
+
e-
e-
EXAMPLE
a. What is the trend in electronegativity across a period?
b. Why does this trend occur?
The Trend is INCREASING
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Decreases Increases Electronegativity
Decreases Increases Ionization Energy
Increases Decreases Atomic Radius
Increases Decreases Metallic Character
Variation down a Group
Variation across a Period
Periodic Property
Summary