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Dmitri Mendeleev. “The elements, if arranged according to their atomic weights, exhibit an apparent periodicity of properties.”. Periodic Trends. St. Kn. Lt. Fi. Dt. E. Oj. Ns. A. Pr. J. Q. Ch. Br. T. Id. Rx. G. Mc. H. Atomic Radius. 1. Atomic Radius. Across Period - PowerPoint PPT Presentation
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Dmitri Mendeleev
“The elements, if arranged according to their atomic weights, exhibit an apparent periodicity of properties.”
Periodic Trends
Background image:http://www.ul.ie/~slc/Pictures/periodic%20table.jpg
Atomic Radius
1. Atomic Radius
Across PeriodAtomic size DECREASESBecause nuclear charge (# p+) increases, as e- are added to same n, pulls e- in tighter
Down GroupAtomic size INCREASESBecause more n (shells), more shielding,
e- further away from nucleus
Background image:http://www.ul.ie/~slc/Pictures/periodic%20table.jpg
Electronegativity
2. Electronegativity
The ability to attract e-
Across PeriodEN INCREASESBecause nuclear charge (# p+) increases
Down GroupEN DECREASESBecause more n, more shielding, e- further
away from nucleus
Background image:http://www.ul.ie/~slc/Pictures/periodic%20table.jpg
Ionization Potential
3. Ionization Potential/EnergyIE: Energy required to remove e-
Higher the IE: more difficult to remove e-
Across PeriodIE INCREASES** with decrease @ each subshellWhy?
Down GroupIE DECREASESWhy?
4. Ionic Radius
Ion-Charged atom
CationPositive (+) ion (neutral atom looses e-)
AnionNegative (-) ion (neutral atom gains e-)
Background image:http://www.ul.ie/~slc/Pictures/periodic%20table.jpg
Ionic Radius
4. Ionic Radius
Across PeriodIR DECREASES** with jump up in size @ metalloids
Down GroupIR INCREASESCompare to neutral atom Ex. Br
Valence e- are the outermost e- of an atom
5. Metallic Properties
Across PeriodMP DECREASES
Down GroupMP INCREASES