Transcript Periodic table and Reactivity

Periodic Table
and Reactivity
Essential Questions:
1. How do valence electrons
determine an atom’s chemical
properties, including reactivity.
2. How are elements classified on the
periodic table?
Periodic Table and Reactivity
Atom
• The basic unit of a chemical
element. (ex: gold, oxygen,
mercury)
• Consists of 3 basic parts.
(protons, neutrons, electrons)
• The atomic mass is the sum of
the protons and neutrons.
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Periodic Table and Reactivity
Electrons
• Negatively charged
subatomic particle.
• Located outside the
nucleus.
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Periodic Table and Reactivity
Valance Electron
• An electron in one of the
outer shells of an atom that
can participate in forming
chemical bonds with other
atoms.
• The number of valance
electrons determines the
element’s reactivity.
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Periodic Table and Reactivity
Periodic Table
• The periodic table arranges
all of the known elements in
order of increasing atomic
number (# of protons).
• Order generally coincides
with increasing atomic
mass, too.
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Periodic Table and Reactivity
What can we tell about this
element (atom) from the periodic
table?
1. The atomic number(14), which is
also the number of protons.
2. The symbol for nitrogen. (Si)
3. The atomic mass. (28.0086)
4. The element’s (atom’s) name.
(Silicon)
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14
Si
28.0086
Silicon
Periodic Table and Reactivity
Periodic Table Classification:
Metals (blue) properties:
• Solid at room temperature (except
mercury)
• Shiny luster
• Ductile (bend into a wire)
• Malleable (hammered)
• Good conductor (heat and
electricity)
• High density
• High melting point
• Reactivity – those metals at the
bottom left corner of the PT are
most reactive
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Metals, Nonmetals & Metalloids
Periodic Table and Reactivity
Periodic Table Classification:
Nonmetals (red) properties:
• No luster (dull appearance)
• Poor conductor of heat and
electricity
• Brittle (breaks easily)
• Not ductile
• Not malleable
• Low density
• Low melting point
• Less reactive than metals
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Metals, Nonmetals & Metalloids
Periodic Table and Reactivity
Periodic Table Classification:
Metalloids (green)
Elements on both sides of
the zigzag line (staircase)
have properties of both
metals and nonmetals.
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Metals, Nonmetals & Metalloids
Quick Action – Match the words with the
definition
With a partner match the classification with the object.
1.
Metal
2.
Nonmetal
3.
Metalloid
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A.
B.
C.
D.
E.
Shiny new Yeti cup
Carbon in your pencil lead
Yellow glob of sulfur
Nitrogen in the air
Silicon used in microprocessors
in cell phones
F. Helium in a balloon
G. An aluminum can
Quick Action – INB Template
Periodic Table INB
2
• Cut out the INB template
and paste the tab of this
template on top of the
previous one, so that it
flips up.
• Circle the groups (1) on
the periodic table in
green.
• Circle the period (2) on
the period table in red.
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1
Periodic Table and Reactivity
Periods on the Periodic Table
• The periods on the PT are the
rows numbered from 1-7.
• Atomic number increases
from left to right.
• Those in the same period
have the same number of
energy levels or shells.
• Chemical properties are not
all similar.
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Periodic Table and Reactivity
Groups on the Periodic Table
• The groups or families on the PT
are the columns numbered from
1-18.
• Same number of valance
electrons.
• Chemical properties are very
similar.
• Groups 1 is the most reactive and
group 18 is the most inert
(stable).
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Quick Action – INB Template
Trends on the Periodic Table
2
• Elements in Period 3 have 3 orbitals
• Elements in Period 7 have 7 orbitals
• Moving down the Period increases the
reactivity
• Cs is more reactive than K
• Li is less reactive than Na
• Draw a down arrow next Period 1-7
and put the words “increasing energy
and reactivity.”
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Increasing energy and reactivity
• Moving down the Period (Rows 1-7)
the number of energy levels or shells
increases by 1.
1
Quick Action – INB Template
• IA Group has one valance
electron.
• 5A Group has five valance
electrons.
• Copy the notes and orange
arrow.
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2
Increasing energy and reactivity
Trends on the Periodic Table
• Groups (Columns 1-18) –
elements have the same
number of valance electrons
in each group.
• Valance electrons are the
electrons in the outer energy
level (shell).
Same# of valance
electrons going
down the column
1
Quick Action – INB Template
Trends on the Periodic Table
• Reactivity increases as you
move from right to left across
the periodic table.
Same# of valance
electrons going
down the column
1
Increasing energy and reactivity
• Draw an arrow indicating
“increasing reactivity.”
2
Increasing reactivity
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Periodic Table and Reactivity
Reactivity of atoms
• The ability of atoms to
combine or separate with
other atoms to create new
substances (chemical
reaction)
• Valance electrons are the key
to this process.
• Reactivity changes across the
periodic table.
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Periodic Table and Reactivity
What makes an atom “happy”
(stable)
• Having its outer energy level (shell)
filled with electrons.
• Example: (8A) highlighted in red.
• These atoms do not want to bond
with other atoms. (inert)
• Helium is the exception because it is
“happy” (stable) with only two
valence electrons.
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8A
Periodic Table and Reactivity
What happens if an atom doesn’t
have 8 valence electrons?
• Hydrogen has only one valance
electron. (Group 1A).
• Does not follow the rule of 8, but
its “happy” number is 2.
Who might hydrogen bond with
to make itself “happy (stable)?”
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Hydrogen
Periodic Table and Reactivity
Hydrogen easily bonds with
itself!
This way both hydrogen
atoms can share an electron
and be “happy (stable).”
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Hydrogen
Hydrogen
Periodic Table and Reactivity
Let’s look at oxygen?
Oxygen has six valence electrons
(It’s in Groups 6A.)
It needs to bond with one atom
that either has two valance
electrons, or two atoms that have
one valance electron.
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Oxygen
Periodic Table and Reactivity
• Now oxygen is “happy”
(stable).
Hydrogen
Hydrogen
• It bonded with 2 hydrogen
atoms making a molecule of
H20 (water).
• Sometimes called the Mickey
Mouse Molecule.
Oxygen
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