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Transcript
Chapter 5
The Periodic Table
Periodic Table Info
Periodic Table Development
Dimitri Mendeleev (1834 – 1907)
• Arranged the elements by increasing ATOMIC
MASS
• Produced the first PERIODIC TABLE – 1871
• The table placed elements with similar
properties in the same column
• Kept “holes” for undiscovered elements, and
predicted the properties in advance
Mendeleev’s Periodic Table
Predicting Properties
New Periodic Table
H. G. Moseley (1887-1915)
• Rearranged the elements by ATOMIC
NUMBER
• This is the MODERN PERIODIC TABLE
What’s on the Periodic Table?
• atomic number
• symbol
• name
• average atomic mass
• electron configuration
Reading the Periodic Table
• GROUP: vertical column (family)
similar chemical properites
• PEROID: horizontal row
same filled energy levels
1
2
3
5
6
7
Period
Group
4
Periodic Table Groups
Properties of Metals
1.
2.
3.
4.
shiny (luster)
conductors of heat and electricity
Reactive with acids
ductile
– can be stretched into a wire
5. malleable
– can be hammered or rolled into sheets
Properties of Nonmetals
1.
2.
3.
4.
Dull and brittle
poor conductors of heat and electricity
Does not react with acids
usually gases at room temp.
PERIODIC LAW
• When elements are arranged in order of
increasing atomic number, their physical
and chemical properties show a periodic
(repeating) pattern.
Which means:
• there are patterns across the periodic
table called periodic trends
Atomic Radius
half the distance from center-center of 2
like atoms
Atomic Radii DOWN a Group
↓ As you go down a group another energy
level is added, the atom size gets larger
Atomic Radius: down group
P
X
X
Na
P P
P P
P
P
P
P
P
P
P
X
X
X
X
X
X
X
X
X
X
Atomic Radius: down group
P
X
X
K
P P
P P
P
P
P
P
P
P
P
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Atomic Radii DOWN a Group
↓ DOWN THE GROUP ATOMIC RADIUS
INCREASES
more energy levels,
the larger the size of the atom
Atomic Radii ACROSS a Period
→ Each atom gains one proton and one
electron in the same energy level
→Each added electron is the same distance
from the nucleus
→The positive charge increases and exerts
a greater force on the electrons thereby
pulling it closer to the nucleus
REMEMBER!
PROTONS
are bigger
and stronger!
+
e
+
P
-electrons
are smaller
and weaker!
Atomic Radius: across period
P
X
X
X
X
X
P P
X
P
P
P
P
P
P
P
X
P
X
X
X
X
Atomic Radii ACROSS a Period
→ACROSS THE PERIOD ATOMIC RADIUS
DECREASES
stronger attraction of protons,
easier to hold on to the electrons
Ionization Energy
amount of energy needed to remove an
electron from an atom
Ion: an atom that has gained or lost electrons
if you lose an electron…
if you gain an electron…
BECOMES POSITIVE!
BECOMES NEGATIVE!
Ionization Energy DOWN a Group
↓ As you go down a group atoms become
larger, electrons are farther from the
nucleus and more easily removed
Ionization Energy DOWN a Group
↓ DOWN THE GROUP IONIZATION ENERGY
DECREASES
greater distance from the nucleus,
the easier to lose an electron
(less energy needed)
Ionization Energy
ACROSS a Period
→As atomic radius decreases there is a
greater attraction between protons and
electrons.
→The stronger the attraction, the more
energy needed to remove an electron.
→The more electrons present, the more
energy required to remove them all to
become STABLE
Ionization Energy
ACROSS a Period
→ACROSS THE PERIOD IONIZATION ENERGY
INCREASES
more electrons on an energy level,
more energy required to remove them all
Electronegativity
tendency for an atom to attract electrons
It is a “tug of war” between the two
.
atoms of a bond
:
:
.
H . F :
Which is the more electronegative element?
Electronegativity
ACROSS the Period
→As you go across a period atomic radius
decreases because there is a greater
attraction between protons and electrons
→Metals do not attract electrons.
→Non-metals do attract electrons.
Electronegativity
ACROSS the Period
→ACROSS THE PERIOD ELECTRONEGATIVITY
INCREASES
stronger the attraction,
the easier to add more electrons
Electronegativity
DOWN the Group
↓ The larger the atom, the less likely it is to
accept more electrons.
Electronegativity
DOWN the Group
↓ DOWN THE GROUP ELECTRONEGATIVITY
DECREASES
farther the distance from the nucleus,
more difficult to attract electrons
PUT IT ALL TOGETHER!
Reactivity of Alkali Metals
Where are the most reactive
metals?
Where are the most reactive
nonmetals?
Activity Series of the Elements
1.Why is sodium not used for
silverware?
It is highly reactive and reacts with water.
2. Why has so much gold jewelry
survived from ancient civilizations?
It does not react with oxygen or
water and therefore does not
readily break down.
3. Why is food canned in containers
made from steel coated with a thin
layer of tin?
Steel makes a strong container and
the tin lining does not react with the
contents.
4. Why are cars painted?
To prevent the iron from rusting by
being exposed to oxygen in air.