Alchemy Inv III Lesson 6 Electron GPS HonChem

Alchemy Unit – Investigation III

Lesson 7: Electron GPS

The Big Question

• How do electron subshells relate to the periodic table?

You will be able to:

• Identify an element based on its electron configuration.

Activity Purpose: This lesson you will learn another way to show the distribution of electrons in an atom called electron configuration.

(cont.)

Orbitals per subshell •  The s-subshell has

one s-orbital •  Each p subshell from

level 2 and above have three separate p-orbitals.

•  There are 5 separate orbitals in the d subshell.

•  How many separate f-orbitals are in an f subshell?

Unit 1 • Investigation III

Electron Configuration

•  Remember that we can get the distribution of electrons in an atom by following 3 rules to give us the most stable distribution of electrons in an atom called the ground state configuration.

•  Any other distribution of electrons is either not allowed or is in a less stable distribution (higher energy) called an excited state.


Quantum Numbers


Erwin Schröndinger developed a mathematical model that incorporated what scientists knew about the electron during the first half of the Twentieth Century. One of the key features of his model was that it took into account both the particle and wave behavior observed in electrons

Aufbau Principle


Electrons fill the orbitals with the lowest energy first.

Pauli Exclusion Principle


No two electrons may have the same set of quantum numbers. These are the values of variables that result in a solution to the Schrödinger equation which gives us the allowable energy and locations of electrons in an atom.

In practical terms, this results in a maximum of 2 electrons can occupy an orbital and must have opposite spins.

Hund’s Rule

•  When more than one orbitals in the same subshell is available, each orbital receives an electron before the electrons are paired.

•  This results in distributing electron in an atom that that the lowest energy state.



•  Another way to represent the distribution of electrons in an atom is to write out the shell and subshells where electrons are found.

•  The shells and subshells should be written out in the order of shell number.

•  The total number of electrons in the subshell is written as superscript to the right of the shell and subshell is used.


• An electron configuration is an ordered list of orbitals occupied electrons for a given atom.

• The number of electrons in a subshell is specified as a superscripted number.

Notes

• The ground-state electron configuration is a list of all the subshells that have electrons for a given element filled from the lowest to the highest energy subshell.

• The excited-state electron configuration has one or more electrons for a given element not in the lowest possible energy subshell.

Notes

Writing Electron Configurations •  Notice, the shell that the subshell belongs is written first. •  Then give the subshell where you are placing the

electrons. •  Finally give the number of electrons in the subshell as a

superscript.

Activity •  When you write out the electron configuration for an

atom that uses more than one subshell, start with the electrons in the lowest subshell first.

•  Then write the next highest subshell. If there are more than one equivalent subshell (such as “p” subshells), you can write all the electrons in those subshells together in one superscript.



Compare the orbital representation with the electron configuration for fluorine (9).

1s2 2s2 2p5



Compare the orbital representation with the electron configuration for sulfur (16).

1s2 2s2 2p6 3s2 3p4 3p3 3p2 3p1



Compare the orbital representation with the electron configuration for vanadium (23).

1s2 2s2 2p6 3s2 3p6 4s2 3d3

Electrons in Subshells Order of Filling By Subshells

Maximum # electrons

1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2


1.  What seems to be the maximum number of electron that can be placed into any s-subshell?

2.  What is the maximum number of electron that can be placed into any p-subshell?

3.  What is the maximum number of electron that can be placed into any d-subshell?

Rules for writing …

•  Except for a few exceptions in the “d” and “f’ subshell, the lowest numbered subshells are filled with electrons before the higher ones. This is because the electrons placed in lower-numbered subshells also have lower (and more stable) energy.

•  The locations of each set of electrons are written from left to right.

•  For example, the electron configuration for nitrogen’s 7 electrons is …


N: 1s2 2s2 2p3

Practice Element Atomic

number #

electron Electron

Configuration

Carbon Fluorine Sodium Neon

Calcium


6 6 1s2 2s2 2p2

9 9 1s2 2s2 2p5

11 11 1s2 2s2 2p63s1

10 10 1s2 2s2 2p6

20 20 1s22s22p63s23p64s2

More Practice

•  Fill out the ground state electron configuration for the first two periods of the periodic table.


Abbreviated or Noble Gas Notation

•  Some electron configurations can become very long. Chemists often use a shortened method of writing the configurations. This method is called the abbreviated electron configuration or noble gas notation.

•  The abbreviated or noble gas configuration substitutes a bracket and the symbol of the noble gas ([He]) for the portion matching the core noble gas shell filled to reach the target element.


Abbreviated or Noble Gas Notation

•  Brackets by themselves should not be used for noble gases.

Neon is [He] 2s2 2p6 and not [Ne] •  Only noble gas core shells can be used. Germanium is [Ar] 3d10 4s2 4p2, not [Zn]4p2.



Order of Filling By Subshells

Maximum # electrons

1s 2

2s 2

2p 6

3s 2

3p 6

4s 2

3d 10

4p 6

5s 2

4d 10

5p 6

6s 2

4f 14

5d 10

6p 6

7s 2

[He] = 1s2 = 2

[Ne] = 1s22s22p6 = 10

[Ar] = 1s22s22p63s23p6

= 18

[Kr] =1s22s22p63s23p6

4s23d104p6 = 36

[Xe] =[Kr]5s25d105p6

= 54

[Rn] =[Xe]6s24f145d10

6p6

= 86

Abbreviated Electron Configuration


To get the abbreviated electron configuration for sulfur (16) , [Ne] is substituted for the first 10 electrons.

1s2 2s2 2p6 3s2 3p4 [Ne] 3s1 3p1 3p2 3p3



To get the abbreviated electron configuration for vanadium (23), we can substitute [Ar] for the first 18 electrons.

1s2 2s2 2p6 3s2 3p6 4s2 3d3 [Ar] 4s1 3d2 3d1

Practice Element Atomic

number #

electron Electron

Configuration

Carbon Fluorine Sodium Neon

Calcium


6 6 1s2 2s2 2p2

9 9 1s2 2s2 2p5

11 11 1s2 2s2 2p63s1

10 10 1s2 2s2 2p6

19 19 1s22s22p63s23p64s2

[He] 2s2 2p2

[He] 2s2 2p5

[Ne] 3s1

[Ar]4s2 [He] 2s2 2p6

More Practice

•  Fill out the ground state electron configuration for the period 3 and period 4 of the periodic table using the noble gas notation.


Electron configuration Element

[He]2s1

Nitrogen, N

[Ne]3s23p5

[Ar]4s23d6

[Ar]4s23d104p2

Tellurium,Te

Making sense Copy and complete the chart below.

Lithium, Li

[He]2s22p3

Chlorine, Cl

Iron, Fe

Germanium, Ge

[Kr] 5s24d105p4

Making Sense

• What is the same about the electron configurations for the elements in the alkali metals family?

• What is the same about all the electron configurations for the elements in the alkali earth family?

Making Sense

• What is the same about all the electron configurations for the elements in the boron family?

• What is the same about all the electron configurations for the elements in the carbon family?

• What is the same about all the electron configurations for the elements in the nitrogen family?

Making Sense

• What is the same about all the electron configurations for the elements in the oxygen family?

• What is the same about all the electron configurations for the elements in the halogen family?

Making Sense

• Except for helium, what is the same about all the electron configurations for the elements in the noble gas family?

• What happens to the electron configuration for the element that follows an noble gas?

Making Sense

• What do the electron configurations for the elements in the transition metals family have in common?

• How does the shell level compare to the period number that the transition elements are found?

• How does the shell level compare to the period number for the “s” and “p” subshells?

Making Sense

• How is the organization and structure of the periodic table related to electron subshells?

• Examine the chart on the next slide. How does the energy level for the “f” subshell compare to the period number of the elements with “f” subshell electrons?

(cont.)

Making Sense

Making sense

• How many “s” orbitals are there per shell?

• What is the maximum number of electrons that can be placed into any “s” subshell?

• What shell do “p” orbitals first appear? How many “p” orbitals are there per shell?

• What is the maximum number of electrons that can be placed into “p” subshell in one shell?

Making sense • What shell do “d” orbitals first appear? • How many “d” orbitals are there per shell? • What is the maximum number of electrons

that can be placed into “d” subshell for one shell?

• What shell do “f” orbitals first appear? How many “f” orbitals are there per shell?

• What is the maximum number of electrons that can be placed into “f” subshell for one shell?

Making sense

• Explain how you can use a periodic table to get the ground-state electron configuration for any element.

Making Sense


f-block (n-2)

s-bl

ock

(n)

p-block (n) d-block (n-1)


1s1 1s2 2s1 2s2 2p1 2p2 2p3 2p4 2p5 2p6 3s1 3s2 3p1 3p2 3p3

Full electron configuration


[Ar] 4s1 4s2 3d10 4p1 4p2 4p3 4p4

Abbreviated electron configuration


s2dx s1dx+1


s2dx s0dx+2


s2dx s1dx+1


S2 d1 fx s2 d0 f x+1

See chapter 8 of text

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Alchemy Inv III Lesson 6 Electron GPS HonChem