Download Ionization energy

Chapter 5:
The Periodic Law
General Chemistry
http://www.ccsdualsnap.com/miscellan.htm
Review/Link to Previous
Learning
• In Chapter 4, we learned about electrons
configurations of elements.
• Discovered there is a pattern of electron
configurations on the Periodic Table.
• Are there other patterns on the Periodic
Table? _____________
• In Chapter 5 we will learn how the Periodic
Table is organized.
Collections
Do you like to play cards?
Do you have a stamp, baseball
card, or comic book collection?
How do you organize your collection?
Attempts at Organizing Elements
• Early scientists knew about some properties
of elements.
• Is there a characteristic of elements that can
organize them?
Dobereiner’s Triads
THE LAW OF TRIADS:
_________________________________________
_________________________________________
_________________________________________
EXAMPLE:
Lithium
Sodium
Potassium
Atomic Mass of 7
Atomic Mass of 23
Atomic Mass of 39
According to Dobereiner’s Law, the atomic mass of sodium
Should equal the arithmetic mean of lithium and potassium.
(7+39)/2 = 23, which is the mass of sodium.
Problems with Dobereiner’s
Law of Triads.
1) ______________________________________
________________________________________
2) The law did not work for very low or very high
massed elements such as F, Cl, and Br.
3) As techniques improved for measuring atomic
masses accurately, the law became obsolete.
Dobereiner’s research made chemists look at groups of
elements with similar chemical and physical properties.
Newland’s Law of Octaves
When placed in increasing order of their atomic
masses, __________________________________
________________________________________.
Li Be B C N
Na Mg Al Si P
K Ca
O
S
F
Cl
Problems with
Newland’s Law of Octaves
1) _____________________________________
________________________________________.
2) When more elements were discovered
(Noble gases) they could not be accommodated in his
table.
However, the modern periodic table does draw from the
concept of periods of eight.
Mendeleev and Meyer
• Published nearly identical schemes for classifying
elements
• Arranged elements by ______________________
• Mendeleev generally given more credit
– Published first
– More successful at demonstrating value of table
– ______________________________________
______________________________________
Mendeleev’s Table: ______________________________.
He arranged the table so that elements in the same column
have similar properties.
Problems with Mendeleev’s Table:
1) The positions of ________________ could not be
accommodated within the table.
2) In order to make the elements fit the requirements,
Mendeleev was forced to put an element of slightly
higher atomic weight ahead of one of slightly lower
atomic weight.
Henry Moseley (1887-1915)
• Developed concept of _________________
– amount of positive charge in the nucleus
• Later determined that arranging periodic
table according to ___________________
eliminated problems seen in Mendeleev’s
table
Why is it the “periodic” table?
• Periodic Law: when elements are
arranged in order of increasing
atomic number,
____________________________
____________________________
Study Buddy Review
• Describe the contribution each person
below made to the development of the
periodic table:
–
–
–
–
–
Johan Dobereiner
John Newland
Dmitri Mendeleev
Julius Meyer
Henry Moseley
Parts of the Periodic Table
Parts of Periodic Table
• Groups/families: vertical columns
–
–
–
–
–
–
–
__________________1A
__________________2A
Boron, carbon families
__________________ (oxygen family).
pnictogens (nitrogen family)
__________________ (fluorine family): 7A
___________________8A/0
• Horizontal rows are called periods
• There are 7 periods
• The elements in the A groups are
8A
1A
0
called the representative elements
2A
3A 4A 5A 6A 7A
outer s or p filling
Parts of Periodic Table
• Metals: _____________ of staircase
• Nonmetals: __________of staircase
• Metalloids: elements adjacent to staircase
(except Al, Po)
The group B are called the
transition metals
 These
are called the inner
transition metals and they
belong here
Study Buddy Review
• Identify the follow parts of the periodic table:
–
–
–
–
–
–
–
–
Halogens
family
Alkali metals
Metals
Inner transition metals
Noble gases
Metalloids
Period
Periodic Properties of Elements
Periodic Trends
•Atomic Radius
•Ionic Radius
•Ionization Energy
•Electron Affinity
•Electronegativity
Atomic Radius
}
Radius
•Atomic Radius = ____________________________
___________________________________________
Trends in Atomic Radius
• Influenced by three factors:
1. ________________
– More charge pulls electrons in closer.
2. Energy Level
– Higher E level _________________________
3. Shielding effect
– The number of electrons between electrons and
nucleus affects the pull felt by the outer
electrons
Atomic Radius
Group trends
• As we go down a
group...
• ______________
______________
______________
• so the atoms get
bigger.
H
Li
Na
K
Rb
Atomic Radius Periodic Trends
• As you go across a period, the radius gets
smaller.
• ___________________________________
___________________________________
Na
Mg
Al
Si
P
S Cl Ar
Atomic Radius
0.250
Atomic Radii
Atomic radius, nm
0.200
0.150
0.100
0.050
Atomic Radii
0.000
3
4
5
6
7
8
9
10
11
12
13
atomic number, Z
14
15
16
17
18
19
20
Ionic Size
• Ion: electrically charged atom
• Cation: __________ charged ion
• Anion: ___________ charged ion
• Ions aren't the same size as the neutral
atoms they come from.
– Compare the sizes of sodium and chloride ions
with the sizes of sodium and chlorine atoms.
• Positive ions are
smaller than the
atoms they come
from.
• _________________
_________________
_________________
_________________
_________________.
• Negative ions are
bigger than the atoms
they come from.
• Although the
electrons are still all in
the 3-level, the extra
repulsion produced by
the incoming electron
causes the atom to
expand. There are still
only 17 protons, but
they are now having to
hold 18 electrons.
Study Buddy Review-A.R., I.R.
• Describe the pattern for atomic radius
– As you move across a period
– As you move down a column
• What charge does a cation have?
• What charge does an anion have?
• Which is larger than its parent atom, a
cation or an anion?
First Ionization Energy
• Ionization energy __________________________
__________________________________________
• Elements want to have the e- configuration like
that of a noble gas (filled)
– Column 1A elements have need to _____ one electron
to have noble gas configuration so it is ________ to
remove electron
– Column 7A element need to GAIN one electron to have
noble gas configuration, so it is HARD to remove
electron
First Ionization Energy vs.
Atomic Number
Ionization Energy
Ionization Energy
• As you move down

a group ionization
energy decreases…
• ________________
________________
________________
________________
________________
________________
• As you move
across a period
ionization energy
increases…
• Elements on left of
table want to lose
electrons to have
full energy level
(requires low
energy to remove
electron)
Successive Ionization Energies
• more than one electron can be removed
from atoms
• Second Ionization energy: ______________
_____________________________________
• Third Ionization energy: when a third
electron is removed from an atom that has
already lost two electrons
Sucessive Ionization Energies
Symbol First
H
He
Li
Be
B
C
N
O
F
Ne
1312
2731
520
900
800
1086
1402
1314
1681
2080
Second
Third
5247
7297
1757
2430
2352
2857
3391
3375
3963
11810
14840
3569
4619
4577
5301
6045
6276
Relationship Between Common
Charge and I.E.
• Consider Beryllium:
– Electron config: [He] 2s2
• Low energy to remove 1st and 2nd electrons
• MUCH higher energy to remove 3rd
electron because
___________________________________
___________________________________
Study Buddy Review-I.E.
• What is ionization energy?
• Describe the pattern for ionization energy as
you
– Move down a family
– Move across a row
• What does “first” ionization energy mean?
Electron Affinity
Electron affinity is:
• ___________________________________
___________________________________
• the more attraction for an electron the
energy is released when the atom gains the
electron
– Released energy is ______________ (-350 kJ)
Electron Affinity
Electron Affinity
General Trend:
• ________________ (s2p5 configurations)
are most negative electron affinities. They
are most likely to want to gain electrons to
obtain noble gas configuration
• As you go down a family, electron affinity
is ______________(harder to gain electrons
with increasing atomic size)
Study Buddy Review-E.A.
• What does it mean when an energy is
negative?
• Which elements generally have a very
negative electron affinity?
Electronegativity
Electronegativity:
___________________
______________________to itself when it is
chemically combined with another element.
• As you move down a
group, electronegativity
___________
• As you move across a
period, electronegativity
_____________
Which element is the MOST electronegative?
Electronegativity
Electronegativity
4
3.5
3
2.5
2
1.5
1
0.5
0
1
2
3
4
5
6
7
8
9
10
11
12
atom ic num ber, Z
13
14
15
16
17
18
19
20
Study Buddy Review-Electroneg
• Define electronegativity.
• Describe the pattern for electronegativity as
you
– Move down a group
– Move across a period
• Which element is the most electronegative?
Resources
• http://www.chemguide.co.uk/atoms/properties/atra
dius.html
• http://wine1.sb.fsu.edu/chm1045/notes/Periodic/A
ffinity/Period05.htm
• http://www.webelements.com/
• http://www.public.asu.edu/~jpbirk/CHM113_BLB/Chpt07/sld017.htm
• Jeanette Boles
• Tina Lula
• Dr. Stephen L. Cotton, Charles Page High School