Transcript Unit 4 Trends ppt

Periodic Table
Trends
Trends of the Periodic Table:
At the conclusion of our time
together, you should be able to:
1. Give a trend across and down the Periodic
Table for metallic characteristics, reactivity,
atomic radius and ion radius, electron affinity,
ionization energy, electronegativity, density,
melting point and boiling point
2. Pick the element with the higher trend above
from a list of several elements
Atomic Radius
½ the distance between the nuclei of two
identical atoms that are bonded together.
1.
Electron – electron repulsion
Makes radius larger
1.
Very weak interactions
Atomic Radius con‘t
2. Proton – electron attraction =
Makes radius smaller
Very Strong interactions

Proton electron attraction is a million times
stronger than electron electron repulsion
Atomic Radius con’t
Down a group/family
3. Energy level, n, increases from
top to bottom
Radius gets larger by adding large
amounts of electrons
Think Bohr model (adding rings)
Atomic Radius Trends
Atomic Radius Trends
Top to Bottom
Left to Right
Increases
Decreases
Electron Affinity
The energy change that occurs
when a neutral atom acquires an electron.
Electron Affinity Trends
Top to Bottom
Left to Right
Decreases
(less negative)
Increases
(more negative)
Noble Gases = 0
Ionization Energy
The energy required to remove one electron
from a neutral atom.
The closer to the nucleus, the harder to pull the
electron.
The farther away, more interference from other
electrons, therefore, the easier it is to pull the
electron.
Ionization Energy Trends
Ionization Energy Trends
Top to Bottom
Left to Right
Decreases
Increases
Electronegativity
The ability of an atom to attract electrons.
The most electronegative element is
F – Fluorine
It is assigned the number 4 and all other values
are based on that value.
Electronegativity Trends
Electronegativity Trends
Top to Bottom
Left to Right
Decreases
Increases
Ionic Radius
1.
Cations lose electrons, therefore they tend
to be
Positive Ions - Metals
2.
Anions gain electrons, therefore they tend
to be
Negative Ions - Nonmetals
Ionic Radius Trends
More electron – electron
repulsion = larger radius
Less electron – electron
Repulsion = smaller radius
Ionic Radius Trends
Metals
Nonmetals
Smaller
Larger
Anion radius is larger compared to
the atom
Cation radius is smaller compared
to the atom
Metallic Character
1.
2.
3.
4.
5.
Low ionization energy
Low electronegativities
High luster – shiny
Good conductor or electricity and heat
Malleable and ductile
Most metallic element = Francium
Metallic Characteristic Trends
Top to Bottom
Left to Right
Increases
Decreases
Conductivity
Shininess
Malleability
Ductility
Non Metallic Character
1.
2.
3.
4.
5.
High ionization energy
High electronegativities
Little or no metallic luster
Poor electrical and thermal conductors
Fewer solids
Most nonmetallic element = Fluorine
Metalloid Character
1. Characteristics of both metals and
nonmetals
2. Electronegativities between those of
metals and nonmetals
3. Ionization energies between those of
metals and nonmetals.
4. Boiling pts, Melting pts and Densities
vary widely
Silicone
1. High luster
2. Brittle
3. Good conductor
Reactivity Trends
metals ….Francium
nonmetals …Fluorine
Top to Bottom
Left to Right
Increases with
Metals
Decreases with
Nonmetals
Decreases with
Metals
Increases with
Nonmetals
Density
Mass of a Material / Volume of that Material
Density Trends
Density Trends
Top to Bottom
Left to Right
Increase
Increases then
Decreases
Boiling Point
Temperature at which a system moves from the
liquid state to the gaseous state. The
external pressure pushing into the liquid is
equal to the internal pressure pushing out of
the liquid.
Melting Point
The temperature at which a solid becomes a
liquid. The external pressure pushing into the
solid is equal to the internal pressure pushing
out of the solid.
Boiling Point Trends
Boiling/Melting Point Trends
Top to Bottom
Left to Right
Increases except
Groups 1, 2, 12,
13, 14
Increases then
Decreases
Trends of the Periodic Table:
Let’s see if you can:
1. Give a trend across and down the Periodic
Table for metallic characteristics, reactivity,
atomic radius and ion radius, electron affinity,
ionization energy, electronegativity, density,
melting point and boiling point
2. Pick the element with the higher trend above
from a list of several elements