0801 Chapter 3.2 1
Physical
Science 9 The Periodic Table
0801 Chapter 3.2 2
Physical
Science 9 The Periodic Table
0801 Chapter 3.2 3
Physical
Science 9 Atomic Structure
The Periodic Table groups elements together much like a grocery
store groups items in the same aisle.
Where is the Malt-O-
Meal you rebel scum!
0801 Chapter 3.2 4
2:00
0801 Chapter 3.2 5
Physical
Science 9
Simplified Periodic Table
See pages 78-79 in your text
0801 Chapter 3.2 6
Periodic Table with electron configurations
0801 Chapter 3.2 7
Standard Periodic Table
0801 Chapter 3.2 8
1:50
0801 Chapter 3.2 9
Standard Periodic Table
0801 Chapter 3.2 10
Standard Periodic Table
Symbol – A one or two letter
abbreviation for an element.
The first letter is ALWAYS
upper case.
Atomic Number – The
number of protons in the
atom. The periodic table is
arranged in proton order
from left to right.
Element name – The name of
the element.
Atomic Mass – The number of grams of one mole of the element (mass of
the element). Elements that have more protons generally have more mass,
therefore mass increases as you move from left to right.
0801 Chapter 3.2 11
Standard Periodic Table
You do NOT have to memorize data in the Periodic
Table. It will ALWAYS be available to you for tests and
homework.
The Periodic Table is your FRIEND!!!
0801 Chapter 3.2 12
Physical
Science 9 Other Periodic Tables
0801 Chapter 3.2 13
Physical
Science 9 Other Periodic Tables
0801 Chapter 3.2 14
The Periodic Table of the
Elements Created by an old Russian guy
named Dmitri Mendeleev in 1869.
He arranged the known elements of his
day in a table with each column
representing elements that had similar
chemical properties.
0801 Chapter 3.2 15
The Periodic Table of the
Elements
His original table included spaces for
elements that had not been discovered yet.
I was a genius of my time, and I
also had many, many bad hair
days.
0801 Chapter 3.2 16
The Periodic Table of the
Elements
Mendeleev’s Table had some problems,
but they pretty much eliminated when his
table was modified to list elements
according to atomic mass.
0801 Chapter 3.2 17 17:00
0801 Chapter 3.2 18
The Periodic Table
According to your book, there
are 92 naturally occurring
elements.
However, only 88 have actually
been found in nature. The
others have been synthesized
in labs or in atomic reactions.
Uranium (U, atomic number 92) is the heaviest naturally occurring
element. All of the heavier elements 93-118 were created in labs by
shooting a stable atom with protons hoping one will stick. Some of these
atoms exist only for nanoseconds before the extra proton is dumped.
0801 Chapter 3.2 19
Physical
Science 9 Electron Configuration
The electron configuration of an atom is a form of notation which
shows how the electrons are distributed among the various atomic
orbital and energy levels.
Orbitals are filled in a certain
order. Energy levels are not
filled one at a time – many times
the higher energy orbitals (d
and f) are skipped.
0801 Chapter 3.2 20
Physical
Science 9 Electron Configuration
Example – Hydrogen has 1 electron. Using the chart below, it is
easy to see that the 1s orbital would be used to store this one
electron. Therefore, hydrogen’s electron configuration would be…
1s1
The first number is the energy
level of the atom where the
electron is.
The letter is the orbital that the
electron is in.
The exponent is the number of
electrons held in that orbital.
0801 Chapter 3.2 21
Physical
Science 9 Electron Configuration
How about Helium? It has two electrons in each atom. The electron
configuration for Helium would be…
1s2
0801 Chapter 3.2 22
Physical
Science 9 Electron Configuration
What about Oxygen? It has eight electrons in each atom. The
electron configuration for Oxygen would be…
1s2 2s2 2p4
If you add up all the exponents, it
should equal the number of
electrons
0801 Chapter 3.2 23
Physical
Science 9 Electron Configuration
Let’s blow you away with a tough one. Let’s write the electron
configuration of Krypton.
1s2 2s2 2p6 3s2 3p6
4s2 3d10 4p6
0801 Chapter 3.2 24
Physical
Science 9 Electron Configuration
0801 Chapter 3.2 25
0801 Chapter 3.2 26
0801 Chapter 3.2 27
Physical
Science 9 Electron Configuration Using the Periodic Table to do electron configurations
0801 Chapter 3.2 28
Physical
Science 9 Electron Configuration Shortcut Using Noble Gases
0801 Chapter 3.2 29
0801 Chapter 3.2 30
Physical
Science 9 Ions vs. Atoms
All atoms have a common goal…
It is the same goal that many of us have…
We want to have a fulfilling life…
Atoms want to be full as well…
It is each atoms goal to acquire EIGHT (8) electrons in
its outer energy level (there are a few exceptions
which we’ll cover later.)
0801 Chapter 3.2 31
Physical
Science 9 Ions vs. Atoms
As you remember from a previous discussion, the
outer energy level electrons are called valence
electrons.
As it turns out, the closer an atom is to having eight
valence electrons the more effort it has to attain that
goal.
Those atoms that are just one away from eight will do
almost anything to gain another electron…stealing is
their way of life…pillaging is their MO (modus
operandi)…
0801 Chapter 3.2 32
Physical
Science 9 Ions vs. Atoms
A chlorine atom has 7 electrons, and is
searching for one more to take from someone.
Along comes a sodium atom. The sodium atom
has only one valence electron. If it could get
rid of it, it would then have 8 valence electrons!
Sodium wants to get rid of
that one electron as much as
Chlorine wants to gain one,
so Sodium easily gives it up
and both atoms are happy!
However, they are not atoms
anymore…
0801 Chapter 3.2 33
Physical
Science 9 Ions vs. Atoms
Since the Chlorine atom
has added an electron, it
has also added an
additional negative
charge (remember,
electrons are negative).
So now the atom is not
electrically neutral
anymore…it has been
ionized! It is now an ion!
Since the Chlorine atom gained one negative charge, it’s overall charge
is -1. The Sodium atom has given up an electron, so its overall charge is
+1. This charge is called the VALENCE of an ion.
0801 Chapter 3.2 34
Physical
Science 9 Ions vs. Atoms
If an atom GAINS
electrons, it becomes
NEGATIVELY charged…
If an atom LOSES
electrons, it becomes
POSITIVELY charged.
0801 Chapter 3.2 35
Physical
Science 9 Ions vs. Atoms
If an atom LOSES electrons, it becomes POSITIVELY
charged…
…these ions are called
CATIONS
0801 Chapter 3.2 36
Physical
Science 9 Ions vs. Atoms
If an atom GAINS electrons, it becomes NEGATIVELY
charged.
These ions are called anions
0801 Chapter 3.2 37
Physical
Science 9 Octet Rule Exceptions
Hydrogen, Helium, Lithium, and Beryllium (the first
four elements) are happy with two valence electrons,
since the first energy level can only hold two
electrons, so it’s full!
0801 Chapter 3.2 38
Atomic number vs. Mass number
The ATOMIC NUMBER is the number of protons in the
atom.
The mass number is the number of protons and
neutrons in the nucleus.
The mass number of an atom can vary depending on
the number of neutrons. Atoms of almost any
element can have different number of neutrons.
0801 Chapter 3.2 39
Atomic number vs. Mass number
Carbon, for instance, can commonly have 6, 7 or 8
neutrons in each atom.
They would be referred
to as C-12, C-13 or C-14.
0801 Chapter 3.2 40
Atomic number vs. Mass number
When you look at the Periodic Table, you will notice
that Carbon has an atomic mass of 12.011.
If all of the Carbon atoms had 6 neutrons, the atomic
mass would be exactly 12.000.
But since there are
some C-13 and C-14
atoms mixed in, it raises
the atomic mass
slightly.
0801 Chapter 3.2 41
Atomic number vs. Mass number
These variations in the number of neutrons are
called
ISOTOPES
So, C-12, C-13, and C-14
are isotopes of Carbon.
0801 Chapter 3.2 42
Calculating the number of Neutrons
To calculate the number of neutrons any atom has,
take the mass number and subtract the atomic
number (the number of protons).
C-14 has a mass
number of 14, with an
atomic mass of 6.
14-6 = 8 neutrons
0801 Chapter 3.2 43
Deathly Isotopes
Many isotopes are harmless. The water you drink
everyday contains isotopes of both hydrogen and
Oxygen (H-1, H-2, O-16, O-17 and O-18.
Isotopes that are
radioactive (give off
energy as they decay)
are dangerous and can
damage living cells.
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0801 Chapter 3.2 45
Mass of a Single Atom
The mass of a single atom is extremely small.
Units like grams, pounds, and ounces are way too
big for the mass of an atom.
Scientists came up with a unit that can be used
with atoms. It is called the Atomic Mass Unit.
It is defined as 1/12th the mass of a Carbon-12 atom.
Since Carbon-12 has 6 protons and 6 neutrons, and
since electrons contribute very little to the overall
mass, it can be assumed that each proton and
neutron have a mass of 1 AMU.
0801 Chapter 3.2 46
Avogadro’s Number
So where do the atomic masses found in the Periodic
table come from?
Scientists came up with a quantity
unit called the moles. 1 mole = 6.02
x 1023.
This number was named after a
funny-looking Italian scientist,
Lorenzo Romano Amedeo Carlo
Avogadro. We call it Avogadro’s
number.
0801 Chapter 3.2 47
Avogadro’s Number
If you take 6.02 x 1023 atoms (1 mole) and place them
on a scale, you would come up with the atomic mass.
6.02 x 1023 is a BIG number.
If you had a mole (6.02 x
1023) of coke cans, they
would cover the entire
surface of the Earth with a
depth of 200 miles.
0801 Chapter 3.2 48
Avogadro’s Number
However, when you’re talking about something as
small as atoms, a mole of copper atoms would fit in a
tablespoon.
0801 Chapter 3.2 49
That’s All Folks