Answer:
<h2>Oxygen has six valence electrons, two in the 2s subshell and four in the 2p subshell.</h2>
<h3>Valence electrons are the electrons in the outermost shell, or energy level, of an atom. </h3>
<h3>Configuration of oxygen's valence electrons as 2s²2p⁴.</h3>
Explanation:
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Answer:
ΔS = -661.0J/mol is the entropy change for the system 
ΔS = -842J/mol.K is the entropy change for the surroundings
Explanation:
From the relationship between ΔG, T, ΔH and ΔS,
Mathematically, ΔG = ΔH - TΔS
TΔS = ΔH - ΔS
ΔS = ΔH - ΔS / T
but ΔG = -54 kJ/mol, ΔH = -251 kJ/mol and T = 25 °C (298 K)
plugging into the equation, 
ΔS = -251 kJ/mol - ( -54 kJ/mol) / 298
ΔS  = -0.6610KJ/mol or in J.mol
ΔS = -661.0J/mol is the entropy change for the system
- For entropy change for the surroundings = ΔS = ΔH/T
 
- ΔS = -0.84KJ/mol.K or -842J/mol.K is the entropy change for the surroundings
 
 
        
             
        
        
        
Answer:Lithium
Explanation:Lithium has 3 protons, and 4 neutrons making it the lightest element that isn't a gas.