1.) What is the ground-state electron configuration of the oxide ion O2−? Express your answer in condensed form, in order of increasing orbital energy. For example, [He]2s22p2 should be entered as [He]2s^22p^2 .

2.) Which element has the following configuration: [Xe]6s24f15d1?
Enter the chemical symbol for the element.

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.

c, liquids evaporate, creating a gas