brief
an ele
configuration con
1. a number indicates the
2. a letter indicates the type of orbital; s, p, d, f
3. a superscript indicates the number of electrons in the orbital. exampl
in the s orbital of the first energy level. the element is helium.
how to write an electron configuration:
a. determine the total number of electrons to be represented.
b. use the aufbau process to fill the orbitals with electrons. the aufbau process requires that electrons fill the
lowest energy orbitals first. in another words, atoms are built from the ground upwards.
c. the sum of the superscripts should equal the total number of electrons. example: 12mg $1s^2 2s^2 2p^6 3s^2$
configuration writing practice
write a ground state electron configuration for each neutral atom. ground state means that all of the lowest
possible energy levels (up to the proper number of electrons for the element) are filled.
1. na 3. sr 5. n 7. ti 9. cl
2. pb 4. u 6. ag 8. ce 10. hg
write a ground state electron configuration for these ions. remember that ions have a change in the total
number of electrons (positive have lost electrons and negative have gained). example: $n^{3-}$ is $1s^2 2s^2 2p^6$. it
has three extra electrons
11. $o^{2-}$ 12. $fe^{2+}$ 13. $b^{3+}$ 14. $ni^{2+}$ 15. $k^+$ 16. $co^{3+}$
17. if each orbital can hold a maximum of two electrons, how many electrons can each of the following hold?
a. 2s c. 4f e. 4d
b. 5p d. 3d
18) isoelectronic species have similar electron configurations. which of these are isoelectronic?
a)$li^+$, h, he b) $ca^{2+}$, ne, $s^{2-}$

Question

brief
an ele
configuration con
1. a number indicates the
2. a letter indicates the type of orbital; s, p, d, f
3. a superscript indicates the number of electrons in the orbital. exampl
in the s orbital of the first energy level. the element is helium.
how to write an electron configuration:
a. determine the total number of electrons to be represented.
b. use the aufbau process to fill the orbitals with electrons. the aufbau process requires that electrons fill the
lowest energy orbitals first. in another words, atoms are built from the ground upwards.
c. the sum of the superscripts should equal the total number of electrons. example: 12mg $1s^2 2s^2 2p^6 3s^2$
configuration writing practice
write a ground state electron configuration for each neutral atom. ground state means that all of the lowest
possible energy levels (up to the proper number of electrons for the element) are filled.
1. na  3. sr  5. n  7. ti  9. cl
2. pb  4. u  6. ag  8. ce  10. hg
write a ground state electron configuration for these ions. remember that ions have a change in the total
number of electrons (positive have lost electrons and negative have gained). example: $n^{3-}$ is $1s^2 2s^2 2p^6$. it
has three extra electrons
11. $o^{2-}$  12. $fe^{2+}$  13. $b^{3+}$  14. $ni^{2+}$  15. $k^+$  16. $co^{3+}$
17. if each orbital can hold a maximum of two electrons, how many electrons can each of the following hold?
    a. 2s  c. 4f  e. 4d
    b. 5p  d. 3d
18) isoelectronic species have similar electron configurations. which of these are isoelectronic?
    a)$li^+$, h, he  b) $ca^{2+}$, ne, $s^{2-}$

Accepted Answer

# Explanation:
## Step1: Determine Na's atomic number
Sodium (Na) has an atomic number of 11, so it has 11 electrons.
## Step2: Apply Aufbau principle
Fill orbitals in order of increasing energy: $1s$ (max 2), $2s$ (max 2), $2p$ (max 6), $3s$ (max 2), etc.
- $1s^2$ (2 electrons)
- $2s^2$ (2 electrons, total 4)
- $2p^6$ (6 electrons, total 10)
- $3s^1$ (1 electron, total 11)

# Answer:
The ground - state electron configuration of Na is $1s^{2}2s^{2}2p^{6}3s^{1}$

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QUESTION IMAGE

Question

Explanation:

Step1: Determine Na's atomic number

Step2: Apply Aufbau principle

Answer: