Transcript The Periodic Table

Bell Ringer - Riddles
1. The man who invented it doesn't want it. The man
2.
3.
4.
5.
who bought it doesn't need it. The man who needs it
doesn't know it. What is it?
I run over fields and woods all day. Under the bed at
night I sit not alone. My tongue hangs out, up and to
the rear, awaiting to be filled in the morning. What am
I?
Throw it off the highest building, and I'll not break. But
put me in the ocean, and I will. What am I?
What can run but never walks, has a mouth but never
talks, has a head but never weeps, has a bed but
never sleeps?
No sooner spoken than broken. What is it?
Answers to Riddles
1.
A coffin
3. A tissue
or a wave
2.
A shoe
Answers to Riddles cont.
4. A river
5. Silence
or a secret
The Periodic Table
Chapter 5
p.133-164
History
Structure
Trends
Section I:
Attempts at Classification
Dobereiner - 1817
Discovered groups of three
elements with similar
properties
“Triads”



Ca – 40 amu
Sr – 87.6 amu
Ba – 137 amu
Mass of Sr is about ½ way
between Ca and Ba
Newlands - 1863
Arranged elements in order
of increasing atomic mass
Found a repetition of similar
properties with every 8th element
“Law of octaves”
7 column table with 7 rows
Mendeleev - 1870
Arranged elements in order
of atomic mass with 8 long
columns and several short
columns
Arrangement reflected properties of the elements
Predicted existence of several elements to fill
gaps in his table

These elements were later discovered and had the
properties predicted
Mendeleev’s Periodic Law
Properties of the elements are a
periodic function of their atomic
masses.
Moseley - 1913
Performed experiments to
determine an accurate mass for
several elements which seemed
out of place on the table
Noticed a pattern in the number of
protons
Reorganized elements in order of atomic
number rather than mass
Modern Periodic Law:
The physical and chemical properties
of elements are periodic functions of
their atomic numbers.
Modern Periodic Table
Most significant addition to
Mendeleev’s periodic table
came with the discovery of
the noble gases.
A new row was added to the
periodic table after their
discovery.
Section II:
The Modern Periodic Table
Periods
7 rows
Can be determined from
the element’s electron
configuration (ec)
Example: arsenic has an
ec= [AR] 3d104s24p3
the 4 in 4p3 means that
arsenic is in the fourth period
1
2
3
4
5
6
7
Periods
Period
number
1
2
3
4
5
6
7
Number of
elements in
period
2
8
8
18
18
32
32
Sublevels in
order of filling
1s
2s2p
3s3p
4s3d4p
5s4d5p
6s4f5d6p
7s5f6d,etc.
Groups or Families
18 columns
Groups or Families
The group number is the same as the number of
electrons in the outermost energy level of an
atom.
Except groups 10 though 18. The number of
electrons in the outermost energy level of the
atom is the group number -10.
Example: Group 18 is the noble gases
18 – 10 = 8
We already knew that noble gases have 8
electrons in their outermost energy level.
This Arrangement Reflects:
Properties
Increasing atomic number
Electron configuration
Electron Configuration:
Li – 1s22s1
Na –
1s22s22p63s1
K – 1s22s22p63s23p64s1
All have 1 e- in the outer level
All are similar in color and hardness
All react vigorously with water
All belong to family/group 1
Li
Na
K
Same
Family
or
Group
Electron Configuration:
C - 1s22s22p2
C
N
O
N - 1s22s22p3
O-
1s22s22p4
Same period
All have a full 1st energy level with e- in s and p
orbitals of the second level
Number of e- is increasing by 1
All are in period 2
Blocks:
Based on the electron configurations of the
elements, the periodic table can be divided into
four blocks, the s, p, d, and f blocks.
Block Elements
s
p
d
f
Groups
1&2
13 – 18
3 – 12
Lanthanides & Actinides
Blocks:
d
s
f
p
Classification of Elements:
Most of the elements are metals.
Located on the left side of the table.
General Properties of Metals:
1 to 3 e- in outer energy level of most
Lose e- to form bonds (+ ions)
Shiny
Hard
Good conductors of heat
Good conductors of electricity
Classification of Elements Cont.:
Some elements are nonmetals and are
found on the right side of the table.
General Properties of Nonmetals:
5 to 8 electrons in the outer level
Gain e- to form bond (- ions)
Brittle solids or gases
Poor conductors of heat
Poor conductors of electricity
Classification of Elements:
Some elements have properties similar
to both metals and nonmetals.
These are found bordering the stair-step
dividing line.

Exception: Al is a metal
These elements are called metalloids.
metals
metalloids nonmetals
Some of the Families/Groups
Have Special Names.
1 – alkali metals
2 – alkaline earth
metals
3-12 – transition
metals
16 – chalcogens
17 – halogens
18 – noble gases
Elements 58 – 71 –
lanthanides
Elements 90 – 103 –
actinides
Lanthanides and
actinides – rare
earth metals
Think about trends!!!
Trend- to show a tendency
*Mirriam-Webster Online dictionary
I want you to write down every thing
that comes to your mind when you hear
the word trend.
Trends
Since trends are a tendency, they can be
used to classify.
In Chemistry, trends are used to arrange
elements in the periodic table.
Part III:
Trends on the Periodic Table
Atomic Radius
One-half the distance between the nuclei
of identical atoms that are bonded
together.
Radius depends on:


the number of energy levels
the strength of the nucleus
Each group represents a higher
principal quantum number (n)
As n increases, size of the e- cloud
increases.
F
Cl
Br
Atomic radius
increases down a
family.
Across a period, nuclear charge increases by
1 for each element.
A stronger nucleus acts like a stronger
magnet which attracts the e- cloud.
C
N
O
Atomic radius
decreases across a
period.
Determine which is larger?
Na or Rb?
Rb
Ag or Au?
Au
Cl or I?
I
Ni or Cu?
Ni
Al or Si?
Al
La or U?
La
K or Ca?
K
H or He?
H
Ionic Radius
Size of an ion
Ions are charged atoms formed when:
 Atoms lose e (+ Ion)
 Cation
 Atoms gain e (- Ion)
 Anion
Cations- smaller than their respective
neutral atoms. Remember that cations are the + charged ions.
Metals usually lose all valence electrons.
- e-
+
The nucleus pulls tighter on the remaining electrons.
+
more p+ than e-
+
Anions are larger than their respective
neutral atoms. Remember that anions are the - charged ions.
Nonmetals usually gain electrons to complete
the valence shell.
+ e-
-
Electrons repel each other and spread out more.
-
more e- than p+
-
Which is larger?
Ca or Ca+2

Ca
F or


F–1
F–1
K or K+1

K
F-, Ne or Na+
F-
O or O-2

O-2
First Ionization Energy
Energy required to remove one electron from
a neutral atom of an element.
To avoid the influence of nearby atoms,
measurements of ionization energies are
made on isolated atoms in the gas phase.
Factors that affect ionization energy:
1) Radius
2) Nuclear charge
3) Shielding effect
4) Stability of sublevels
1) Radius:
The greater the distance between
the nucleus and the valence
electrons, the easier it is to lose an
electron.
2) Nuclear charge:
Within a period, the higher the
nuclear charge, the higher the
ionization energy.
3) Shielding Effect:
Other e- block the pull of the nucleus
on the outer e-.
Electrons repel each other.
4) Stability of Sublevels:
e- in filled or half-filled sublevels are
extremely hard to remove.

Higher ionization energy than their
immediate neighbors
C
N
Highest IE
O
General Trend for IE:
Ionization energy increases as you go up
a family and across a period.
As the atomic
number
increases, both
the period and
the group
trends become
less obvious
Electron Affinity:
The attraction of an atom for an additional
electron or the energy involved when an
atom gains an electron to form an anion
Factors affecting EA:
1) Size
2) Nuclear charge
3) Shielding effect
4) Stability of sublevels
1) Size:
In large atoms, the nucleus exerts
less pull on the outer level.
2) Nuclear charge:
Within a period, an increase in
nuclear charge creates a greater
attractive force.
3) Shielding effect:
High numbers of electrons repel
additional electrons
4) Stability of sublevels:
Filled or half-filled sublevels are
more stable.

Don’t need any more electrons
General Trend for EA:
EA increases as you go up a family and
across a period.
Electron affinity
Oxidation Numbers:
Position in the periodic table can be used
to predict oxidation numbers.
Elements with sx ec ending
Elements with e- configurations
ending with sx:

Lose x e- to form cations
Elements with dx ec ending
Elements with e- configurations
ending with dx:
Lose s e- first
 Lose d e- one at a time

 If more than 5 d e-, will lose only those in
excess of 5
 If 10 d e-, will lose only s e-
Elements with px ec ending
Elements with e- configurations
ending with px:
Gain e- to complete p and form anions
 Lose p electrons first, then the s
electrons to form cations

Examples:
V
Ca – 4 s2
+2
V – 4s23d3
+ 2, + 3, + 4 and + 5
Fe – 4s23d6
+2 and +3
O – 2s22p4
- 2, +6 and +4