Transcript Periodic Trends

Periodic Trends
Ionization Potential
Atomic Emissions
Electron Affinity
Electronegativity
Metallic character
Atomic Radius
Ionization Energy
 Ionization energy is the energy required to move one electron
from an atom.
 Ionization energy increases as you move across the periodic table
from group 1 to group 8 and decreases as you move down the
periodic table from period 1 to period 7.
 Ionization energy increases across a period because the greater
number of protons (given by the atomic number) attract the
orbiting electron more strongly, thereby increasing the energy
required to remove one of the electrons.
 Ionization energy decreases down a group because the valence
electrons are further away from the nucleus and therefore
experience a weaker attraction to it.
Ionization Energy
Electron Affinity
 Electron affinity is the energy required to detach an electron
from a singly-charged anion.
 Electron affinity increases as you move across the periodic
table from group 1 to group 8 and decreases as you move
down the periodic table from period 1 to period 7.
 Electron affinity increases across a period because of the
larger attraction from the nucleus and the atom wanting the
electron more as it reaches maximum stability.
 Electron affinity decreases down a group because of the large
increase in the atomic radius.
Electron Affinity
Metallic Character
Metals tend to be
 Be shiny, lustrous, and malleable
 Be good conductors of both heat and electricity
 Have low ionization energies (so they commonly for cations)
 Form ionic compounds with chlorine (metal chlorides)
 Form basic, ionic compounds with oxygen (metal oxides)
Metallic character
 -decreases as you move across the periodic table from group 1 to group
8
 -increases as you move down the periodic table from period 1 to period
7
Metallic Character
Atomic Emissions
Is the emission of radiation as electrons of an atom
move from excited state to ground state
 As a result of the electron transition there is
visible emission on a spectrum
 The gap in energy between the initial and final
state determines the wavelength of light emitted
Electronegativity
 Electronegativity is the chemical property that describes how
well an atom or molecule attracts electrons and therefore
tends to become a negative ion. The higher the
electronegativity, the more it attracts electrons.
Electronegativity is shown as a dimensionless quantity
running from approximately 0.7 to 3.98. Generally, as you
move across the periodic table from group 1 to group 8,
electronegativity increases and as you move down the
periodic table from period 1 to period 7, electrongativity
decreases.
Electronegativity
Atomic Radius
 The atomic radius of an atom is the average distance from the
nucleus of the atom to the boundary of the electron cloud.
The concept is generally difficult to define because electrons
do not have definite orbits and have conceptual positions
around the atom’s nucleus. Atomic radius is measured in
picometers (1x10-12m) and most elements fall in the range
of 30-300 pm. Generally, as you move across the periodic
table from group 1 to group 8, atomic radius decreases and as
you move down the periodic table from period 1 to period 7,
atomic radius increases.
Atomic Radius