Download Ionization energy

Trend
is pattern of change in properties of elements
in periods and groups
Trend
is pattern of change in properties of elements
in periods and groups
Trend
is pattern of change in properties of elements
in periods and groups
What is trend of change in temperature from
January first to June 30
How does number of electrons change in
periodic table?
H
How does number of protons change in
periodic table?
H
How does atomic mass change in periodic
table?
H
How does atomic mass change in periodic
table?
H
Atomic Properties and Periodic Table
The periodic trends of the following
properties will be studied here.
Atomic radius
Metallic and Non-metallic character
Ionization (energy) potential
Electronegativity
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Metals
Nonmetals
Metalloids
Transition metals  good conductors, shiny
Alkali metals  most reactive metals
Alkaline earth metals  reactive metals
Halogens  most reactive nonmetals
Noble gases  don’t react
What makes a good metal?
 Hardness
 Ductility
 Malleability
 Conductivity
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The properties of the elements change from metallic to
nonmetallic going from left to right of the table.
Elements become more metallic going down a family in
the periodic table.
LEAST
METALLIC
H
MOST
METALLIC
Trends across the period
Metallic character of elements
decreases as we move to the right.
Elements to the left have a
pronounced metallic character while
those to the right have a non-metallic
character.
Non-metallic character increases
from left to right.
Rules of Electrostatic force between charged partices
Rules of Electrostatic force between charged
partices
1. Same charge repel
2. opposite charges attract
3. More the distance weaker the force
4. More the charge stronger the force
General definition
To compare atoms in groups always look for distance, greater
the
distance, weaker the pull
To compare atoms in periods always look for charge, greater
the
charge, stronger the pull
Atomic radius or atomic size
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
The atomic size of the elements change from small to
large from left to right of the table.
Atoms size increase going down a family in the periodic
table.
Smallest
Size
H
ATOMIC
SIZE
Increase
The Size of Atoms
Atomic Radius
General definition
It is the distance from the center of the nucleus to the outermost shell of an
atom.
Size increase in groups because shells increase
Size decrease from left to right periods because charge increase
Discussion Topics
What are rules of electrostatic forces?
What rule is used to compare atoms in same period?
What rule is used to compare atoms in same groups?
What cause change in size of atom in periods?
What cause change in size of atom in groups?
Which atom loves it valence (outermost)
electron the most?
Which atom loves it valence (outermost)
electron the least?
Which atom can give valence (outermost)
electron most easily?
Which atom will not give valence (outermost)
electron easily?
According to Bohr
What cause electrons to jump out to higher
energy levels?
According to Bohr
If electron jump out to higher energy levels,
Then what happens to pull force between the
outmost electron and protons?
Ionization energy (IE).
The amount of
energy required to
remove the most
loosely bound
electron from an
isolated gaseous
atom is called
ionization energy
(IE).
Ionization energy (IE).
The amount of
energy required to
remove the most
loosely bound
electron from an
isolated gaseous
atom is called
ionization energy
(IE).
Ionization energy (IE).
The amount of energy required to remove the most
loosely bound electron from an isolated gaseous atom is
called ionization energy (IE).
It is measured in the units of electron volts (eV) per atom
or kilo joules per mole of atoms (kJ mol-1).
Factors Governing Ionization Energy
•Size of the atom/ distance of the valence electron to the
nucleus
•the nuclear charge
Size of the atom
As the size of the atom increases the outermost
electrons are held less tightly by the nucleus
(attractive force between the electron and the
nucleus is inversely proportional to the
distance). As a result it becomes easier to
remove the electron and therefore the
ionization energy decreases with the increase in
atomic size.
Ionization energy: Is the energy required to remove an
electron from a neutral atom.
A.
Ionization energy INCREASES
Ionization
energy
INCREASES H
Fr
H
e
Ionization energy: Is the energy required to remove an
electron from a neutral atom.
A.
Ionization energy INCREASES
Ionization
energy
INCREASES H
Fr
H
e
Charge on the nucleus
•The attractive force between the
nucleus and the electron increases with
the increase in nuclear charge making it
more difficult to remove an electron.
•The ionization energy thus increases with
the increase in the nuclear charge.
Variation along a period
The ionization energy increases with increasing atomic
number in a period.
This is because
The nuclear charge increases on moving across a
period from left to right. So pull between the
valence electron and nucleus increase.
Therefore
more energy is needed to remove the electron and
hence ionization energy keeps increasing.
Variation down a group
The ionization energy gradually decreases in moving
from top to bottom in a group.
This is due to the fact that:
An increase in the atomic size due to an additional
energy shell. Greater distance of the valence shell from
the center decrease the pull force, the valence electron
fell “less loved”
The effect of increase in atomic size is much more than
the effect of increased nuclear charge.
As a result ,
the electron becomes less firmly held to the nucleus and
so the ionization energy decreases as we move down the
group.
Electronegativity:
The ability to be negative increase.
The ability to steal electron from nearby atom
Electronegativity: The electronegativity of an atom is the
tendency of the atom to attract electrons from a
neighboring atom.
Electronegativity: The electronegativity of an atom is the
tendency of the atom to attract electrons from a
neighbouring atom
Electronegativity: The electronegativity of an atom is the
tendency of the atom to attract electrons from a
neighbouring atom
When going from the left to the right across the periodic
table the electronegativity of the atoms will INCREASE.
When going down a family of the periodic table the
electronegativity of the atoms will DECREASE.
Electronegativity.
This the relative tendency of an atom in a
molecule to attract a shared pair of electrons
towards itself.
The value of electronegativity of an element
describes the ability of its atom to compete for
electrons with the other atom to which it is
bonded.
Electronegativity:
Variation along a period
The electronegativtiy increases with increasing atomic
number in a period.
This is because
The nuclear charge increases on moving across a
period from left to right. So pull between the
valence electron and nucleus increase.
Therefore
Atoms have greater ability to pull electron from
neighboring atoms,
they ability to be negative increase.
Variation down a group
The ionization energy gradually decreases in moving
from top to bottom in a group.
This is due to the fact that:
An increase in the atomic size due to an additional
energy shell. Greater distance of the valence shell from
the center decrease the pull force, the valence electron
fell “less loved”
The effect of increase in atomic size is much more than
the effect of increased nuclear charge.
As a result ,
Atoms have less ability to pull electron from neighboring
atoms,
they ability to be negative decrease
What happens if two atoms of equal electronegativity bond
together?
Consider a bond between two atoms, A and B.
If the atoms are equally electronegative, both have the same
tendency to attract the bonding pair of electrons, and so it will be
found half way between the two atoms.
To get a bond like this, A and B would usually have to be the same
atom.
Example,
H2, O2, Cl2 molecules.
This type of covalent bond is described as a non-polar
covalent bond.
Electronegativity
?
?
Chemistry 11
Chemical Bonding
Electronegativity – the tendency of an atom to
attract electrons from a neighbouring atom.
Hey! I
find your
electrons
attractive
!
Get
lost,
loser!
Electronegativity decreases as you move down each column.
Electronegativity increases as you move from left to right.
Periodic Properties of the elements
Atomic Properties
Atomic radius
Atomic properties and the periodic table—a summary
Ionization energy
Atomic radius
metallic character
Ionization energy