Periodic Trends Flashcards
Effective nuclear charge formula
Z (atomic number - shielding constant)
wherein sc = # of inner e- &
atomic number = Z
what does a high Zeff value mean?
stronger attraction of valence e- to nucelus
what do you call ions with the same number of electrons but with different overall charges
ISOELECTRONIC SERIES
WHAT element has equal Zeff and Z?
Hydrogen cuz no electron shielding
3 ways to measure the size of an atom
Covalent Radius
Metallic Radius
van der Waals Radius
Trend for Atomic Radius?
Increasing: left, down
Decreasing Zeff: left, down
Where is the basis for Ionic Radius?
Isoelectronic Series
Comparison of size of cation and anion with PARENT NEUTRAL ATOM
cation < parent (less e-)
anion > parent (more e-)
Effect of subtraction & addition of e- TO
- e- repulsion
- Z eff
- sub - less
- more - add - more
- less
(1) repulsions between electrons in the same principal shell decrease because fewer
electrons are present, and (2) the Zeff felt by the remaining electrons increases because there are
fewer electrons to shield one another from the nucleus.
IONIZATION ENERGY (2 definitions)
- energy required to remove an e-
- related to the tendency of atoms to form CATIONS
Main trend present in IONIZATION ENERGY
and (2) reasons for this
INCREASING: right, up
the succeeding e- after the 1st removed will require greater energy because…
as you remove e-,
- the nucleus becomes more positively charged thereby increasing the attraction of e- toward the center
- there are less e- = less repulsive forces
MAIN TREND present in Electron Affinity
INCREASING: right, up
Electron Affinity (2 definitions)
- change in energy as atom gains/loses e-
- related to the tendency to form ANIONS
highest EA value
Chlorine
Exception to EA
Nobles Gases cuz stable
