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Atomic Orbital Filling Order and Electron Configurations.

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Presentation on theme: "Atomic Orbital Filling Order and Electron Configurations."— Presentation transcript:

1 Atomic Orbital Filling Order and Electron Configurations

2 There are 3 main rules for filling atomic orbitals 1. Aufbau principle - Electrons get filled in order from lowest to highest energy levels. Each atom has seven possible energy levels (cleverly labeled 1 through 7). One is the lowest, seven is the highest. They go by period (rows) in the periodic table. Each atom has seven possible energy levels (cleverly labeled 1 through 7). One is the lowest, seven is the highest. They go by period (rows) in the periodic table. The possible number of electrons for an energy level is found by using the equation 2n 2 (where n = an energy level, 1-7). The possible number of electrons for an energy level is found by using the equation 2n 2 (where n = an energy level, 1-7).

3 Each energy level is further divided into sublevels. There are four basic types of sublevels which are arranged by groups. Each energy level is further divided into sublevels. There are four basic types of sublevels which are arranged by groups. s -- The “s” sublevel has one orbital. s -- The “s” sublevel has one orbital. p -- The “p” sublevel has three orbitals. p -- The “p” sublevel has three orbitals. d -- The “d” has 5 orbitals. d -- The “d” has 5 orbitals. f -- The “f” sublevel has 7 orbitals. f -- The “f” sublevel has 7 orbitals.

4 Increasing energy 1s 2s 3s 4s 5s 6s 7s 2p 3p 4p 5p 6p 3d 4d 5d 7p 6d 4f 5f Orbital diagram Aufbau is German for “building up” We must follow this orbital energy diagram! Notice that the 4s orbital will fill before the 3d because it is lower in energy!

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6 2. Pauli exclusion principle - Only two electrons can fit in each orbital, one with an “up” spin, the other with a “down” spin - Only two electrons can fit in each orbital, one with an “up” spin, the other with a “down” spin -This means that each “s” has 2 electrons, “p” has 6 (3 orbitals with 2 e- each), “d” has 10, and “f” has 14. -This means that each “s” has 2 electrons, “p” has 6 (3 orbitals with 2 e- each), “d” has 10, and “f” has 14. To show the different direction of spin, a pair in the same orbital is written as:

7 3. Hund’s rule When filling a sublevel with multiple orbitals (p, d, or f), each orbital gets one electron (the “up” spin) before any get two. When filling a sublevel with multiple orbitals (p, d, or f), each orbital gets one electron (the “up” spin) before any get two.

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9 Orbital Diagram form Sodium 1s 2s 2p 3s 3p 4s Sodium has 11 electrons Energy

10 Electron Configuration An atom’s electron configuration is the position of its electrons around the nucleus. It reflects the orbital filling diagram. An atom’s electron configuration is the position of its electrons around the nucleus. It reflects the orbital filling diagram. The electron configuration of Sodium is 1s 2 2s 2 2p 6 3s 1 The electron configuration of Sodium is 1s 2 2s 2 2p 6 3s 1 -- This goes in order on the periodic table from the first level to last electron the atom has. -- This goes in order on the periodic table from the first level to last electron the atom has. The number in front of the letter tells the current energy level (1-7). The number in front of the letter tells the current energy level (1-7). The letter tells you the sublevel. The superscript after the letter tells you how many electrons have been filled in that sublevel. The letter tells you the sublevel. The superscript after the letter tells you how many electrons have been filled in that sublevel.

11 Writing Electron Configuration of Sodium 1s 2s 2p 3s 3p 4s Energy 1s 2 2s 2 2p 6 3s 1

12 Electron Configurations - Ions If you know how many electrons an element or ion has, you can write its electron configuration or draw its orbital filling diagram. If you know how many electrons an element or ion has, you can write its electron configuration or draw its orbital filling diagram. Even for an ion! Even for an ion! Example - Na has 11 electrons, Na +1 (the ion) has 10 electrons. Example - Na has 11 electrons, Na +1 (the ion) has 10 electrons. Ions will form so that it ends with a completely filled main energy level. Ions will form so that it ends with a completely filled main energy level.

13 Writing Electron Configuration of Sodium Ion 1s 2s 2p 3s 3p 4s Energy 1s 2 2s 2 2p 6 3s 1 Na + Means it lost 1 electron Na+ electron configuration 1s 2 2s 2 2p 6

14 Adding Electrons = (-) Ions If it needs one to three more electrons to complete the main energy level, then it will tend to gain those electrons and become a (-) charged ion. If it needs one to three more electrons to complete the main energy level, then it will tend to gain those electrons and become a (-) charged ion. –If it needs to gain 1 electron, it is a (-1) charged ion. –If it needs to gain 2 electrons, then it will become a (-2) charge ion. Etc……

15 Removing Electrons = + Ions If the atom has 3 electrons or less in a main energy level, then it will lose those electrons to become a (+) charge ion. If the atom has 3 electrons or less in a main energy level, then it will lose those electrons to become a (+) charge ion. –If it loses 1 electron  +1 ion, –if it loses 2 electrons  +2 ion, etc.


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