Download Ch. 6 PPT

Ch. 6 Periodic Trends
Finish learning the Elements and their symbols
1-36, 38
47,50,51,53-56, 78-80, 82, 92
Ch. 6 The Periodic Table
Valence
Electrons:
Electrons found
in the last/outer
shell of an
atom. Past the
full inner shells
that do not
change.
The Octet Rule: Atoms tend to go thru reactions that
allow them to gain or lose electrons until they have 8
valence electrons. (Exceptions: H,He, Li, Be, B)
lose 1 lose 2
lose 3 gain 4 gain 3 gain 2 gain 1
lose 4
+1
+3
+2
+- 4
-3
-2
-1
no change
0
Valence Electrons
Elements that gain electrons tend to behave in similar ways
Elements that lose electrons tend to behave in similar ways
Development of the Periodic Table
KC 1 : They used the properties of the elements to sort
them into groups
Precursors to the Periodic Table
Triads = groups of 3 elements with similar properties
Octaves = when ordered by atomic weight, the
tendency of atoms to repeat properties every
8th element
Dmitri Mendeleev - Russian scientist that organized the
elements into a table
KC 2: Increasing Atomic Weight (no protons yet)
Unfortunately, it doesn’t increase in order
Development of the Periodic Table
KC 1 : They used the properties of the elements to sort
them into groups
Precursors to the Periodic Table
Triads = groups of 3 elements with similar properties
Octaves = when ordered by atomic weight, the
tendency of atoms to repeat properties every
8th element
Dmitri Mendeleev - Russian scientist that organized the
elements into a table
KC 2: Increasing Atomic Weight (no protons yet)
Unfortunately, it doesn’t increase in order
Mendeleev’s Table
Predicted properties of elements
that had yet to be discovered
Ekasilicon:
Atomic Wt: 72
Melt Pt: High
Density: 5.5 g/mL
Color: Gray
No Rxn: acid / base
Germanium (1886)
Atomic Wt: 72.6
Melt Pt: 947C
Density: 5.4 g/mL
Color: Gray
No Rxn: acid / base
Modern Periodic Table
KC 3: By the number of protons, or Atomic Number
Group: vertical column of the Table, having the
same number of valence electrons or e- config
- also called families
Period: horizontal rows of the Table, show a gradual
changing of properties
Periodic Law: When elements are arranged in order
of increasing Atomic # their properties begin to
repeat in a predictable pattern (think Mendeleev)
Modern Periodic Table
Periodic Trend: A property that repeats itself in a
predictable way when following the Table
Group: vertical column of the Table, having the
same number of valence electrons or e- config
- also called families
Period: horizontal rows of the Table, show a gradual
changing of properties
Periodic Law: When elements are arranged in order
of increasing Atomic # their properties begin to
repeat in a predictable pattern (think Mendeleev)
Modern Periodic Table
Common Periodic Trends:
Physical Properties:
Density
Melting and boiling points
Metallic nature
Atomic Trends:
Electronegativity
Atomic radius
Ionic size
Ionization energy
IUPAC = Intl Union of Pure and Applied Chemistry
Groups Numbered 1-18
1A - 8A = this is the grouping we use, it emphasizes
valence electrons
1B - 8B/10B = is the “d” block, we won’t use this
much
Broad Classes of Elements
KC 4: Metals, Non-metals and metalloids or semimetals
Metallic <----> Metalloids <----> Non-Metals
Lose electrons
Gain electrons
Luster (Shiny)
not ...
Malleable
not…..
Ductile
not…..
Conduct Heat
not….
Conduct Electricity
not….
Mostly Solids
Gases
Outliers: Mercury, Bromine, Aluminum
Properties of the Group I & II Metals
Section 6.2
KC 10: Names
Symbols
Atomic #
Atomic Wt.
Valence (Oxidation States)
Electron Configuration
Density
Melting and boiling point
Section 6.2
KC 11: Representative elements (1-7), Noble
Gases (8), Transition Metals (d block), and Inner
Transition Metals (f block)
Section 6.3
Atomic Radius: essentially the distance from the
nucleus to the valence shell
KC 16: Increases by the number of Energy Levels
as you move down a group, and decreases as you
add protons when you move across a period
Atomic Radii
Atomic Radius increases as you move down the Periodic Table
because you are adding a new Energy Level
Atomic Radius decreases as you move across the Periodic
Table from the left to the right because you are adding more
protons, thereby strengthening the nuclear positive charge that
is pulling inward on the electrons
Ionic Size - change in the size (radius) of an atom when
it gains or loses electrons
Ion = An atom that has gained or lost an electron and
now has a net charge (positive or negative)
KC 17 : When at atom gains or loses an electron
Cation = A positively charged atom that has lost one or
more electrons
Anion = A negatively charged atom that has gained one
or more electrons
KC 19: If the atom gained electrons then it gets bigger.
If the atom loses electrons then it gets smaller.
It means the electrons now outnumber the protons, and
so the nucleus can’t hold the size of the atom as small,
and it gets bigger. Losing electrons is the opposite.
Cation = loses electrons so it decreases in size
loses its entire valence shell
protons outnumber electrons, “pull” them inward
Anion = gains electrons so it increases in size
fills valence shell
electrons outnumber protons and “loosen” outward
Grey = Neutral Radii,
Red = Cationic Radii, Blue = Anionic Radii
Ionization Energy = The energy need to remove an electron
(to make a negative charge)
KC 18 : Decreases within a group (gets easier to steal an
electron as you go down the table)
Increases across a period (gets more difficult to steal
an electron as they get closer to a full shell)
2nd Ionization Energy - when and why does the spike occur?
Periodic Trends in 1st Ionization Energy
Periodic Trends in 1st Ionization Energy
Non-metals, high 1st IE
C
P
I
As
S
Zn
Se
Si
Ga
Beyond 1st Ionization Energy
Electronegativity = An atom’s tendency to gain
electrons in a bond/compound. (its greediness for
electrons)
KC 20 : It increases as you move up a group and it
increases as you move to the right across a period
Electronegativity would increase as you move across
and up the periodic table.
You are closer to a full shell, and the electrons
are closer to the nucleus in the smaller atoms