Trends in Ionization Energy
All the atoms in the same period have the same valence energy level and the same shielding. The increasing nuclear charge increases the attraction of valence electrons so ionization energy generally increases from left to right. The exceptions at full and ½ filled orbitals break the pattern because removing an electron from a stable (low energy) configuration will require more energy. Li has a low 1st ionization because 2 core electrons block the +3 nuclear charge more than they could block the +10 nuclear charge in the Ne atom that would have large ionization energy. Trends in Electron Affinity
Electron affinity is low for metals and high for nonmetals. It is easiest for group 7Ato get and hold an extra electron because it gets them to full energy level. Electron affinity increases from left to right as atoms become smaller, with greater nuclear charge and get closer to a full energy level. http://hrsbstaff.ednet.ns.ca/benoitn/chem11/units/review/periodic_table/trends_p_table.htm• The electrons in the outer shell are called valence electrons. • Valence electrons are found in the outermost shell of an atom and that determines the atom’s chemical properties. • Elements with the same number of valence electrons tend to react in similar ways. • Because s and p electrons fill sequentially
• A horizontal row on the periodic table is called a period. Elements in the same period have the same number of occupied energy levels. http://www.oakland.k12.mi.us/Portals/0/Learning/PeriodicTable.pdfThe electrons in the partially filled outermost shell (or shells) determine the chemical properties of the atom; it is called the valence shell. Periods 1, 2, & 3
The first three rows of the periodic table, called periods 1, 2 and 3, corresponding to the n=1, n=2 and n=3 levels, visible in the green numbers to the left. Hydrogen is seen to have 1 electron in the 1s level, and to the right, helium, in Group 18, has...
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