1). to achieve an octet in the valence energy level, an oxygen atom will gain two electrons. true false 2). the abbreviated electron configuration for cesium is [kr] 5s24d105p66s1. true false

1) True

2)false

Explanation:

1) oxygen has six electrons in its outermost shell, 1s2 2s2 2p4. This implies that it needs only two more electrons to attain the noble has configuration hence it gains two electrons to form a divalent negative ion.

2) The correct shortened electronic configuration for Ceasium is shown below, followed by the longhand electronic configuration of the element.

Caesium:

Electron configuration:

[Xe]6s1

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s1