(5 points)
2. A neutral atom of phosphorus has 15 electrons. Explain why the electron configuration below is not the correct configuration for a neutral atom of phosphorus in its ground state.
1s2 2s2 2p6 3s2 3p2 4s1

(5 points)
3. Find rubidium, magnesium, and aluminum on the periodic table. Fill in the table below based on the locations of these metals on the periodic table. Be thorough in filling in the far right column!

Element Symbol Group number Number of valence electrons General reactivity of the metal with an explanation for this reactivity based on the number of valence electrons
Rubidium
Magnesium
Aluminum

The reason is, According to Aufbau principle, the electrons will be first filled in the sub-shell having lower orbital energy. As from the given configuration, 3p sub-shell has lower orbital energy than 4s sub-shell. So, the electrons will be filled in 3p sub-shell first. Hence, the ground state electronic configuration of neutral atom of phosphorous is,

[tex]1s^22s^22p^63s^23p^3[/tex]

Answer 3 :

Element Rubidium Magnesium Aluminium

Symbol Rb Mg Al

Group number 1 2 13

Number of valence 1 2 3

electrons

The order of general reactivity on the basis of number of valence electrons.

Rb > Mg > Al

Reason : The reactivity is determined by the number of electrons present in the outermost shell that means the element which have 1 valence electron will be more reactive because they can easily lose electrons.