Given the following electronic configurations, identify how many valence electrons each atom has. A=
Element
Electron Configuration
Number
of
Valence
Electrons
B =
C=
Sodium
(Na)
152 2s 2p 3s
А
DONE
Oxygen (0)
1s 2s 2p
B
Iron (Fe)
1s 2s 2p 3s 3p 452
306
С

sodium=atomic number 11 it electronic configuration is ,K=2, L=8,M=1 Valence is 1

oxygen= atomic number 8 it electronic configuration is K=2, L=6 Valence is 2

iron= atomic number 26 it electronic configuration is K= 2 L= 8,M=8 N=6 Valence 2

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%