Question

electron configurations, valence electrons, dot diagrams
name
date
period:
arrange the following in order of decreasing energy: 2p, 4s, 3s, 3d, 3p

write the electron configuration of each of the atoms listed. determine the number of valence electrons for each atom.

draw the electron dot diagram for each element:

Explanation:

Step1: Determine the order of energy levels

According to the Aufbau principle and the order of filling orbitals based on energy (using the \(n + l\) rule, where \(n\) is the principal quantum number and \(l\) is the azimuthal quantum number:

• For \(2p\): \(n = 2\), \(l=1\), so \(n + l=3\)
• For \(4s\): \(n = 4\), \(l = 0\), so \(n + l=4\)
• For \(3s\): \(n = 3\), \(l = 0\), so \(n + l=3\). When \(n + l\) values are equal (e.g., \(2p\) and \(3s\)), the orbital with higher \(n\) has higher energy. So \(3s>2p\)
• For \(3d\): \(n = 3\), \(l = 2\), so \(n + l=5\)
• For \(3p\): \(n = 3\), \(l = 1\), so \(n + l=4\). When \(n + l\) values are equal (e.g., \(4s\) and \(3p\)), the orbital with higher \(n\) has higher energy. So \(4s>3p\)

Step2: Arrange in decreasing order

Based on the above analysis:
\(3d>4s > 3p>3s>2p\)

Answer:

\(3d>4s > 3p>3s>2p\)