Periodic Properties

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Transcript Periodic Properties

Periodic
Properties
Periodic Table with f-block included
A. Electron Configurations
II. The Modern Periodic Table
• Arises from Periodic
Law:
A. Includes:
1. periods/rows
2. groups/families
• There are 4 categories of
groups:
1. Representative (also Main
Group Elements)
2. Transition elements
3. Inner transition (also
Lanthanide and Actinide)
4. Noble Gases
• Some groups have special names:
– 1A (Alkali Metals)
– 2A (Alkaline Earth Metals)
– 7A (Halogens)
– 8A I (Noble Gases)
• The letters A and B in the group
distinguish families
– A = representative
– B = transition
Groups
• The group # is the number assigned to a
vertical column on the periodic table.
• Another name is a Family.
• 18 groups in the periodic table.
• Groups 1, 2, 13 – 18 are representative (A)
• Groups 3 – 12 are transition (B)
• Some label periodic tables label these
groups.
Periods
• 1. The period number is the number
assigned to a horizontal row on the
periodic table.
• 2. The number of protons increase from
left to right across a period.
• 3. This number is the atomic number.
• The period number indicates how many
energy levels (rings) each atom has.
alkali
Alkaline earth
<---transition-------------------->
h
a
l
o
g
e
n
s
N
o
b
l
e
g
a
s
<-----------------Inner transition------------------>
METALS
•
•
•
•
•
•
shiny-luster
solids (except Hg)
malleable
ductile (stretch to wire)
conduct heat & electricity
most elements are metals
NONMETALS
•
•
•
•
•
solids, liquids & gases
luster-dull
brittle
poor conductors
upper-right hand corner (& H)
Metalliods
• along stairstep line – between B & Al
(Al is not a metalloid!)
• classified as nonmetals but conduct
heat and electricity under certain
conditions
• some metal & nonmetal properties
Group 1 - Alkali Metals
• soft, shiny
• reacts violently with water
• VERY reactive, one valence e- to
lose;
• cation
Alkali metals
• http://www.youtube.com/watch?v=m55kgy
ApYrY&safety_mode=true&persist_safety_
mode=1
Group 2 - Alkaline
Earth Metals
• 2 valence e-; cation
• reactive
• http://www.youtube.com/watch?v=m55kgy
ApYrY&safety_mode=true&persist_safety_
mode=1
Transition Metals
• Elements in groups
3-12
• Less reactive harder
metals
• Includes metals used
in jewelry and
construction.
• Metals used “as
metal.”
Transition Metals
• Groups 3-12
• Ions change – changes
properties
• NOT REPRESENTATIVE!
Halogens
• Elements in group 17
• Very reactive, volatile,
diatomic, nonmetals
• Always found
combined with other
element in nature .
• Used as disinfectants
and to strengthen teeth.
Halogens
• -Group 17
• -1 ions, highly reactive
• 7 valence e-
Noble Gases
• Elements in Group 18
• Noble gases are usually
unreactive.
• This is because they have full
valence shells.
• Elements with full valence shells
do not easily gain or lose
electrons.
Noble Gas Stability
• Atoms want to gain stability, like the
noble gases.
• Atoms will try to gain or lose electrons
to have a full valence shell.
Phases of Elements
• 1. Liquids: You must know: Hg and Br
• 2. Gases: Don’t memorize, but you need
to know their general location. Gases are
towards the right side of the periodic
table.
• 3. Solids: All metals, except Hg mercury
Periodic Trends
MetallicCharacter –
elements having
properties of metals
i)
L to R: metals to nonmetals
ii) Nonmetals are at the right of the Table.
They tend to be insulators and react easily with metals.
iii) Metalloids separate the metals and nonmetals and have
intermediate properties
iv) Noble Gases exist at the extreme right, are chemically stable and
have full valence shells
Atomic Radius
– Atomic radius – size of a neutral atom
• Shielding effect – inner energy levels ‘shield’ the outermost
electrons from the positive charge pull of the nucleus
– Atomic radius increases as you move down the groups
• Great distance (adding energy levels) from nucleus = less pull
towards center
– Decreases as you move left to right
• More pull from nucleus (more protons), but no new distance
– EXCEPTION: Noble Gases – much bigger than group
17 – full outer shell
Atomic Radii
Ionic Size (Radius)
– Ionic Radius - size of an ion
– Cations (+) are always SMALLER than neutral
atom
• Nuclear charge the same, less e- = strong pull inwards
– Anions (-) are always LARGER than neutral atom
• Nuclear charge the same, MORE e- = less pull inwards
– Increases as you go down a group
– Decreases from left to right
Ionic Radii
Ionization Energy
– Ionization energy – the energy that is required to
remove an e- from an atom
– Ion – atom which has gained or lost electrons
• Cation – (+) charged ion (lost e-)
• Anion – (-) charged ion (gained e-)
– Decreases as you move down the periodic table
• Outermost electron gets further from nucleus, easier to pull off
– Increases as you move across a period
• No more distance from nucleus, but higher charge = held more
tightly
Ionization Energy
Electronegativity
• Elements relative ability of its atoms to attract
electrons in a chemical bond
• Fluorine – Most electronegative
• Francium – Least electronegative
• Nobel Gases are left out because they form
very few compounds
• Increase across a period
• Decrease down a group
Electronegativity