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

 Page 142

 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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