Periodic Trends
Atomic Radii• Defined by the edge of its
orbital but since the edges are fuzzy, difficult to determine
• Atomic Radii – half the distance between the nuclei of identical atoms that are bonded together
Atomic/Ionic Radii
Arrange the following groups in order of increasing atomic size:
• Rb, Na, Be
• Sr, Se, Ne
• Fe, P, O
Ionization Energy
• An electron can be removed from an atom if enough energy is used
• Ionization energy – the energy required to remove one electron from a gaseous neutral atom
A + energy A+ + e-
Ionization Energy
Ionization Energy
Arrange the following groups in order of increasing first ionization energy:
• Rb, Na, Be
• Sr, Se, Ne
• Fe, P, O
Electron Affinity
Electron Affinity – the energy change when an electron is added to a gaseous neutral atom, exothermic process
A + e- A- + energy
Electron Affinity
Order the atoms in each of the following sets from the least
exothermic electron affinity to the most.
• N, O, F
• Al, Si, P
Electronegativity• applies when an atom is in a compound NOT
alone• Electronegativity – measure of how strongly
an atom attracts electrons when it is in a compound
• Fluorine (the most electronegative element) is assigned a 4.0 and then all the others were determined by comparison
Electronegativity
Predict some of the properties of element 117 (Uus):
• What will be its electron configuration?• What element will it resemble most
chemically?• What will be the formula of the neutral binary
compounds it forms with sodium, magnesium, carbon, and oxygen?