56. Barium

Barium has an s-orbital di-electron in the 6th shell. It has the same electron configuration as strontium, but with five full shells within that have the identical configuration to xenon. Being one shell larger than strontium, its valence electrons are less well bound. This causes it to have a lower ionization energy and be more reactive and more soluble than calcium and strontium, allowing it to form the 2+ ion more readily.

CLICK HERE to interact with this object

RETURN to the Periodic Table

GROUP II: Beryllium, Magnesium, Calcium, Strontium, Barium

55. Cesium

Cesium has one electron in the 6th shell. It has the same electron configuration as rubidium, but with five full shells within that have the identical configuration to xenon. Being one shell larger than rubidium, cesium has a lower ionization energy and is therefore more reactive, forming the 1+ ion more readily.

CLICK HERE to interact with this object

RETURN to the Periodic Table

GROUP I: Lithium, Sodium, Potassium, Rubidium, Cesium

54. Xenon

Xenon is the sixth element with electrons in the 5p orbital. Xenon has five full shells. Like neon, argon, and krypton, it achieves symmetrical stability without the need to hybridize its 5s and 5p orbitals. It is not as unreactive as the other noble gases since its large size lowers its ionization energy to the point that it can bond with, for example, the electronegative oxygen and fluorine atoms.

CLICK HERE to interact with this object

RETURN to the Periodic Table

GROUP VIII: Helium, Neon, Argon, Krypton, Xenon

53. Iodine

Iodine is the fifth element with electrons in the 5p orbital. It has the same electron configuration as bromine, just one shell larger. Like chlorine and bromine, iodine can support multiple possible molecular geometries, and can sustain multiply bonded atoms (with stronger electronegativity than iodine). (The wireframe simply indicates the boundary of the n=5 shell, since there are no electrons defining the boundary of its sphere.)

CLICK HERE to interact with this object

RETURN to the Periodic Table

GROUP VII: Fluorine, Chlorine, Bromine, Iodine