Transcript Section 3 - E. R. Greenman

Chemistry Chapter 5 Section 3

Atomic Radius
 Definition: ½ distance between center of
adjacent nuclei of bonded atoms

Trends: p141
 Within group, radius increases as go from top to
bottom of table
 Within period, atomic radius decreases as go from
left to right in s and p block
 Transition elements slightly varied due to half and
full d and f orbital
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
Defined:
 Amount of energy required to remove one
electron from an atom
 Atom becomes an ion
 Cation

Trends: p 143
 Within group: generally ionization energy
decreases as go from top to bottom of table
 Within period: ionization energy increases as go
from metal to nonmetal

P 146

Definition:
 Energy change that occurs when an atom gains an
electron
 Ion formed: anion
 If electron affinity is positive, energy must be added,
and atom is unstable

Trends: p 147
 Group trends not constant, but more positive number
as go from top to bottom of group
 Across period, largest negative value in group 17
(halogen)

Definition:
 Electrons available for bonding (usually outer
electrons unless transition element)
 Usually s and p orbital electrons (unless transition)

Trends:
 Within group, valence electrons constant
 Across period, valence electrons increase from left
to right

Cation:
 Formed by losing electron(s)
 Smaller than atom due to loss of electron and
increased pull by nucleus

Anion:
 Formed by gaining electron(s)
 Larger than atom because electrons not as strongly
held

Trends: p 149
 Within group, size of ion increases as go from top to
bottom
 Within period, cations formed on left, anions on right

Defined:
 Measure of ability of atom to attract electrons of
another atom
 Most electronegative element assigned number
4.0 and other calculated wrt this

Trends: p 151
 Group: electronegativity generally decreases as
go from top to bottom of table
 Period: generally increase from left to right across
period
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