Which of the following is the ground state of an atom? which is its excited state? which is an impossible electron configuration? identify the element and briefly explain your choices. a. 1s^2 2s^2 2p^6 3s^2 3p^6 5p^1 b. 1s^2 2s^2 2p^3 3s^2 3p^6 4s^-1 c. 1s^2 2s^2 2p^6 3s^2 3p^7

a. Excited

b. Ground

c. Impossible

Element: Potassium

Explanation:

a.

In this electronic configuration we observe that the last electron is in the 5p energy level, and normally this electron should be in the 4s level.

Since the last electron is at a higher energy level (5p) than the level where the electron should normally be located. This indicates that the atom is in an excited state

b.

In this configuration we observe that the electrons are in the expected energy level (see attached table of energy levels) therefore the atom is in its ground state

c.

In this configuration we observe that in the last level of energy 3p there are 7 electrons which is impossible because the sub-level of energy p can only support a maximum of 6 electrons

To know what the element is we add the electrons distributed in the energy levels

We have a total of 19 electrons

In a neutral atom the total number of electrons is equal to the number of protons in the nucleus.

the number of protons in the nucleus is equal to the atomic number (Z) which is what allows one element to be differentiated from another

the atomic number 19 (total gates in the nucleus) in the periodic table corresponds to potassium

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