Question

brief instructions
an electron configuration is a method of indicating the arrangement of electrons about a nucleus. a typical electron configuration consists of numbers, letters, and superscripts with the following format:

1. a number indicates the energy level (the number is called the principal quantum number.).
2. a letter indicates the type of sublevel/orbital; s, p, d, f.
3. a superscript indicates the number of electrons in the orbital. example: 1s² means that there are two electrons in the ‘s’ orbital of the first energy level. the element is helium.

to write an electron configuration:

1. determine the total number of electrons to be represented.
2. the sum of the superscripts should equal the total number of electrons.

example: mg - 12 is: 1s² 2s² 2p⁶ 3s²
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
2. mn
3. sr
4. cu
5. n
6. he
7. ti
8. be
9. cl
10. al
11. identify the element that has the following electron configuration

a. 1s² 2s²2p⁶ 3s²3p⁶ 4s² 3d¹⁰ 4p⁴

Explanation:

Step1: Recall atomic numbers

Find the atomic number of each element as the atomic number = number of electrons in a neutral atom.

Step2: Follow electron - filling rules

Fill electrons into orbitals according to the Aufbau principle (fill lower - energy orbitals first), Pauli exclusion principle, and Hund's rule.

1. Na (Sodium), atomic number = 11

• Fill electrons: $1s^{2}2s^{2}2p^{6}3s^{1}$

1. Mn (Manganese), atomic number = 25

• Fill electrons: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{5}$

1. Sr (Strontium), atomic number = 38

• Fill electrons: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}$

1. Cu (Copper), atomic number = 29

• Due to the stability of a half - filled or fully - filled d - subshell, the electron configuration is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{1}3d^{10}$

1. N (Nitrogen), atomic number = 7

• Fill electrons: $1s^{2}2s^{2}2p^{3}$

1. He (Helium), atomic number = 2

• Fill electrons: $1s^{2}$

1. Ti (Titanium), atomic number = 22

• Fill electrons: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{2}$

1. Be (Beryllium), atomic number = 4

• Fill electrons: $1s^{2}2s^{2}$

1. Cl (Chlorine), atomic number = 17

• Fill electrons: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{5}$

1. Al (Aluminum), atomic number = 13

• Fill electrons: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{1}$

1. For the electron configuration $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{4}$

• Calculate the total number of electrons by adding the superscripts: $2 + 2+6 + 2+6 + 2+10 + 4=34$
• The element with atomic number 34 is Se (Selenium)

Answer:

1. $1s^{2}2s^{2}2p^{6}3s^{1}$
2. $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{5}$
3. $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}$
4. $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{1}3d^{10}$
5. $1s^{2}2s^{2}2p^{3}$
6. $1s^{2}$
7. $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{2}$
8. $1s^{2}2s^{2}$
9. $1s^{2}2s^{2}2p^{6}3s^{2}3p^{5}$
10. $1s^{2}2s^{2}2p^{6}3s^{2}3p^{1}$
11. Se