periodic table trends & definitions. how to read the periodic table 6 c carbon 12.011 atomic...
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How to read the Periodic Table
6
CCarbon
12.011
Atomic Number
Elemental Symbol
Elemental Name
Atomic Mass
Periodic Law
• When elements are arranged in order of increasing atomic #, elements with similar properties appear at regular intervals.
0
50
100
150
200
250
0 5 10 15 20
Ato
mic
Ra
diu
s (p
m)
Atomic Number
Chemical Reactivity
• Families• Similar valence e- within a group result in similar
chemical properties
Periodic Trends are Influenced by:
• Energy Level• Higher energy levels are further from the nucleus
• Charge on Nucleus (# of protons)• More charge pulls the electrons in closer• + and – attract each other more
• Shielding Effect• Blocking effect
Periodic Trends• Atomic Radius
• size of atom: half the distance between two nuclei of a diatomic molecule
• Increases to the LEFT and DOWN
1
2
3
4 5
6
7
Atomic Radius
• Why larger going down?• Higher energy levels have larger orbitals
• Shielding - core e- block the attraction between the nucleus and the valence e-
• Why smaller to the right? • Increased nuclear charge without additional
shielding pulls e- in tighter
Periodic Trends
• First Ionization Energy• Energy required to remove one e- from a
neutral atom.• Increases going UP and to the RIGHT
1
2
3
4 5
6
7
Periodic Trends• Electronegativity
• Tendency of an atom to attract electrons when chemically combined
1
2
3
4 5
6
7
Ionic Radius
• Cations (+)• lose e-• smaller
• Anions (–)• gain e-• larger
© 2002 Prentice-Hall, Inc.
Ion Group trends
• Each step down a group is adding an energy level
• Ions therefore get bigger as you go down, because of the additional energy level.
Li1+
Na1+
K1+
Rb1+
Cs1+
Ion Period Trends• Across the period from left to right, the
nuclear charge increases - so they get smaller.
• Notice the energy level changes between anions and cations.
Li1+
Be2+
B3+
C4+
N3-O2- F1-
Size of Isoelectronic ions
• Iso- means “the same”• Isoelectronic ions have the same # of
electrons• Al3+ Mg2+ Na1+ Ne F1- O2- and N3-
• all have 10 electrons• all have the same configuration:
1s22s22p6 (which is the noble gas: neon)