What is the mass of 0.500 mole of ba? (watch sf’s) 68.7 g 137.3 g 68.65 g 69 g

68.7g

molar mass of Ba(137.327)x (.500)= 68.6635

.500 has 3 sig figs.

if two electrons have the same n, the same ℓ, and the same ml, then they are in the same orbital. the pauli exclusion principle states that no two identical fermions (a fancy word for electrons and other subatomic particles like electrons) may occupy the same quantum state in an atom simultaneously.

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.