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?