Periodicity Trends in the Periodic Table. Atomic Radius One half the distance between nuclei of...
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Transcript of Periodicity Trends in the Periodic Table. Atomic Radius One half the distance between nuclei of...
Periodicity
Trends in the Periodic Table
Atomic Radius• One half the distance between nuclei of identical
atoms that are bonded together• Decrease across a period due to increasing positive
nuclear charge• Increase down a group due to increasing number of
energy levels (outer electrons are farther from the nucleus)
Ionization Energy
Ion: An atom or group of atoms that has a positive (cation) or negative (anion) charge
Ionization: The formation of an ionIonization Energy: The energy
required to remove one electron from a neutral atom of an element, measured in kilojoules/mole (kj/mol)
Ionization Energy• IE increases for each successive
electron• Each electron removed experiences a
stronger effective nuclear charge• Greatest increase in IE comes when
trying to remove an electron from a stable, noble gas configuration.
Ionization Energy1. IE tends to increase across each period.
• Atoms are getting smaller, electrons are closer to the nucleus
2. IE tends to decrease down a group• Atoms are getting larger, electrons are farther from the
nucleus• Outer electrons becomes increasingly more shielded
from the nucleus by inner electrons
3. Metals have characteristically low IE4. Nonmentals have high IE5. Noble gases have a very high IE
Ionic Radius• Cations have a smaller ionic radius
than corresponding atom• Protons outnumber electrons• Less shielding of electrons
• Anions have a larger ionic radius than corresponding atom
• Electrons outnumber protons• Greater electron-electron repulsion
• Ion size decreases down a group
Electron AffinityEnergy change that occurs when an atom accepts an electron1. Halogens have the highest electron affinities2. Metals have low electron affinities3. Affinity tends to increase across a period and decrease
down a group
ElectronegativityThe ability of an atom to attract electrons when bonded1. Nonmetals have high electronegativity2. Metals have low electronegativity3. Electronegativity increases across a period and
decreases down a group
Electronegativity
Ele
ctro
nega
tivity