5 September, 10:18

# What is the difference between atom A and atom B? A - 1s22s22p63s1 B - 1s22s22p65s1 Answers to choose from: 1) Atom B has lost some inner electrons. 2) The outer electron of atom B has moved to a lower energy state. 3) The outer electron of atom B has moved to a higher energy state.

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1. 5 September, 10:55
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2) The outer electron of atom B has moved to a lower energy state.

Explanation:

Properly writing the sublevel notations:

Atom A = 1s² 2s² 2p⁶ 3s¹

Atom B = 1s² 2s² 2p⁶ 5s¹

Solution:

According to the Aufbau's principle, "the sublevels with the lower energies are filled up before those with higher energies".

The pattern of filling is shown below:

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5d, 6s, 4f, 5d, 6p, 7s, 5f, etc.

The configuration of atom A having a total of 11 electrons follows the Aufbau's rule as we can see.

For atom B, we see a higher energy level which is the 5s coming into the lower energy orbitals. Therefore, the outer electrons of atom B has moved to a lower energy state.