University:
Cameron University
Course:
1364 | General Chemistry I
Academic year:

2024
Views:

34

Pages:

2
Author:

Elise Donaldson

aufbau diagram of Parodic Table Electron configurations to describe and communicate the arrangement of electrons around the nucleus of atoms. Steps for determining electron configurations: 1. Identify how many electrons are in the atom or in ion. Example: Carbon has 6 electrons, Al3+ has 10 electrons. 2. Determine the principal energy level (n) of the atom n = 2 for carbon (it is in the second period), n=3 aluminum (it is in the third period). 3. Determine the number of sublevels.     For the principal energy level (n) there are sublevels (l= 0, 1, 2, 3, n-1). Example: for n = 4, l = 0,1,2,3 Each sublevel has a letter name as: l = 0 l = 1 l = 2 l = 3 l =4 S P d f g Maximum electrons in each subshell: S 2 P 6 d 10 f 14 g 18 𝑛𝑙#𝑒 4. Assign electrons to the sublevels as: follow the order of the subshells (aufbau rule = building-up principle) in the periodic table: Move from top to the bottom periods (rows) in order & from left to right of each period (row). n 1 1 1S 2S 3S 4S 5S 6S 7S 2 3 4 5 6 7 2 3 4 5 6 Aufbau Parodic Table 7 8 9 10 11 12 13 14 15 16 17 18 1S 4f 5f 3d 4d 5d 6d 2p 3p 4p 5p 6p In order as: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p…     1s will be filled first, with the maximum of 2 electrons. 2s will be filled next, with the maximum of 2 electrons. 2p will be filled next, with the maximum of 6 electrons. Continue until no any electrons left. Example: write electron configuration for titanium (Ti) atom.   Look at the periodic table, atomic number is 22. (For a normal atom, atomic number gives number of electrons). Follow the subshells order (aufbau rule): n = 22 2 2 6 2 6 2 2 22𝑇𝑖: 1s , 2s , 2p , 3s , 3p , 4s , 3d Also, an abbreviated method for electron configurations is to use the Core Electrons (Noble Gas Core) for presentation of electron configuration:    Choose the nearest noble gas to the element in your question. Use square brackets [ ] around the chemical symbol of the noble gas. Continue to write remaining subshell after the noble gas core. An Example: Write electron configuration for potassium atom. Solution:  The nearest noble gas element to the potassium is argon (Ar).  The electron configuration for argon is: Ar: 1s2 2s2 2p6 3s2 3p6  The electron configuration for potassium is: K: 1s2 2s2 2p6 3s2 3p6 4s1   As we see Potassium has an argon core plus 4s1 The abbreviated electron configuration for potassium is: K: [Ar] 4s1 An Example: Write electron configurations for vanadium atom and vanadium ion (𝑉 3+ ). Answer: 𝑉: [𝐴𝑟] 4𝑠 2 , 3𝑑 3 𝑉 3+ : [𝐴𝑟]3𝑑 2 Special rule: In general, electrons are removed from the valence-shell s orbitals before they are removed from valence d orbitals when transition metals are ionized.

Aufbau Diagram of Periodic Table

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