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The Periodic Law
Chapter 5
Pages 132 - 164
Orbital Review & Periodic
Table
orbital review
History of the Periodic Table
Who is the father of the periodic table?
Dmitri Mendeleev ~1869
He initially arranged ~60 elements in order of increasing atomic
mass. What two questions remained?
1. Why could most of the elements be arranged in the order
of increasing atomic mass but a few could not?
2. What was the reason for chemical periodicity?
Give an example of something that is periodic.
Henry Mosely, who worked with Ernest Rutherford discovered by
viewing spectral data, that the table fit into patterns better when
arranged by increasing nuclear charge – or increasing _________
__________.
History of the Periodic Table
Periodicity or the periodic law states that the physical and
chemical properties of the elements are functions of their atomic
numbers – when elements are arranged in order of increasing
atomic number, elements with similar properties appear at
regular intervals.
Electron Configuration and
the Periodic Table
Based on electronic configurations of the elements, the periodic
table can be divided into four blocks  s, p, d, and f.
Electron Configuration and
the Periodic Table
Alkali metals are group 1 on periodic table.
silvery
soft enough to be cut with a knife
very reactive
cannot be found in nature as free elements
react strongly with water
Alkaline earth metals are group 2 on the periodic table.
harder, denser and stronger than group 1
higher melting points than group 1
less reactive than group 1
Groups 1 & 2 are also known as the s-block elements.
https://youtu.be/dUbjn3ix3ds
Electron Configuration and
the Periodic Table
d-block elements are called transition metals.
good conductors
high luster
typically less reactive than groups 1 & 2
exist in nature as free elements
What are three very unreactive elements listed by your text?
palladium, Pd
platinum, Pt
gold, Au
Electron Configuration and
the Periodic Table
p-block elements are called the main-group elements
all metalloids
all nonmetals (except hydrogen and helium)
the halogens (group 17)
the halogens are the most reactive nonmetals
why?
because they have 7 valence electrons
https://youtu.be/u2ogMUDBaf4
f-block elements are the lanthanides and actinides
lanthanides are shiny and similar in reactivity to group 2
actinides are mostly laboratory-made elements
Electron Configuration and
Periodic Properties
_________ ___________ may be defined as one-half the
distance between the nuclei of identical atoms that are bonded
together.
From left to right (across a period), atomic radii trend smaller.
Why?
As atomic numbers get bigger (one per element), this means that
each subsequent element has one more ___________. Because of
this increasing nuclear charge (or positive charge), the electrons
orbiting the nucleus are pulled in closer and closer.
From top to bottom (down a group), atomic radii trend larger.
Why?
As elements trend down a group, more s, p, d & f-sublevels are added, and
each s, p, d & f sublevel is a bit larger than the previous.
Electron Configuration and
Periodic Properties
https://youtu.be/VopLrkfXfGw
Electron Configuration and
Periodic Properties
__________ __________ are available to be lost, gained, or
shared in the formation of chemical compounds. They are often
located in incompletely filled outer orbitals. They are the
electrons that participate in chemical bonding.
Often, the charge of valence electrons is concentrated closer to
one atom than to another. This uneven concentration of charge
has significant effects on the chemical properties of a compound.
______________ is a measure of the ability of an atom in a
compound to attract electrons from another atom in a
compound. The most electronegative element is fluorine.
Electronegativity generally increases left to right (across a
period) and decreases top to bottom (down a group). Why?
Electron Configuration and
Periodic Properties
https://youtu.be/nqaclvioesw
Electron Configuration and
Periodic Properties
Electron Configuration and
Periodic Properties
An ______ is an atom or group of bonded atoms that has a positive or
negative charge.
Any process that results in the formation of an ion is referred to as
_____________.
Ionization energy (IE) is the energy required to remove an electron
from a neutral atom of an element. As atomic number increases going
down a group, more electrons lie between the nucleus and the
electrons in the outer orbits. This shields the outer electrons from the
nuclear forces of attraction.
IE increases left to right (across a period) and decrease top to bottom
(down a group). Why?
As elements become more and more like the noble gases, more and more
energy is required to remove an electron and create an ion.
https://youtu.be/ksZoOde-7zY
Electron Configuration and
Periodic Properties
The Periodic Law
Slide
Quiz
In the modern periodic table, elements are arranged according to
what?
Group 17 (halogens) are the most reactive of the nonmetals
because?
What does the periodic law state?
Across period 3 (left to right), the energy needed to remove an
electron from an atom (increases/decreases)?
What is the above periodic trend called?
Which element has the highest electronegativity?
How does ionization trend?
How does atomic radius trend?
Why does atomic radius trend this way?
How does electronegativity trend?
Funny Chemistry