Dmitri Mendeleev
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Transcript of Dmitri Mendeleev
Dmitri Mendeleev
“The elements, if arranged according to their atomic weights, exhibit an apparent periodicity of properties.”
Periodic Trends
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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
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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
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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-)
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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