Transcript Periodic Table Notes Unit 3 – Notes

Periodic Table Notes
Unit 3 – Notes
Periodic Table
Nonmetals are
on the right side
of the periodic
table (with the
exception of H).
Periodic Table
Metals are on
the left side of
the chart.
Periodic Table
Metalloids
border the
stair-step line
(with the
exception of
Al, Po, and
At).
Diatomic Molecules
These seven elements occur naturally as molecules
containing two atoms.
Ions
• When atoms lose or gain electrons, they become
ions.
– Cations are positive and are formed by elements on the
left side of the periodic chart.
– Anions are negative and are formed by elements on the
right side of the periodic chart.
Development of Periodic Table
• Elements in the same
group generally have
similar chemical
properties.
• Physical properties are
not necessarily similar,
however.
Development of Periodic Table
Dmitri Mendeleev
and Lothar Meyer
independently
came to the same
conclusion about
how elements
should be grouped.
Metals versus Nonmetals
• Metals tend to form cations.
• Nonmetals tend to form anions.
Metals
They tend to be
lustrous, malleable,
ductile, and good
conductors of heat and
electricity.
Nonmetals
• These are dull, brittle
substances that are poor
conductors of heat and
electricity.
• They tend to gain
electrons in reactions
with metals to acquire a
noble gas configuration.
Metalloids
• These have some
characteristics of
metals and some of
nonmetals.
• For instance, silicon
looks shiny, but is
brittle and fairly poor
conductor.
Periodic Trends
• In this chapter, we will rationalize observed trends
in
– Sizes of atoms and ions.
– Ionization energy.
– Electronegativity
What Is the Size of an Atom?
The bonding atomic
radius is defined as
one-half of the
distance between
covalently bonded
nuclei.
Measured in nanometers
Nuclear Charge
• The positive charge of the
protons
• For example sodium has a
nuclear charge of +11
Sizes of Atoms
Bonding atomic radius
tends to…
…decrease from left to
right across a row
…increase from top to
bottom of a column
Atomic Radius
Ionization Energy
• The ionization energy is the amount of
energy required to remove an electron from
the ground state of an atom.
– The first ionization energy is that energy
required to remove first electron.
– The second ionization energy is that energy
required to remove second electron, etc.
– Measured in J or kJ
Ionization Energy
• It requires more energy to remove each successive
electron.
• When all valence electrons have been removed, the
ionization energy takes a quantum leap.
Trends in First Ionization
Energies
• As one goes down a
column, less energy is
required to remove the
first electron.
– For atoms in the same
group, Zeff is essentially
the same, but the valence
electrons are farther from
the nucleus.
Electronegativity
• A measure of how well you attract
electrons.
– A scale of 0 – 4
– Created by Linus Pauling