Electrons in Atoms

​Lesson 1.5: Electrons in Atoms

​Let's review our electric hotel for electrons

​You are the desk clerk....

​

Check in Fluorine​

​Check in Calcium

Multiple Choice

How many sub-levels are in the 2nd Energy Level

• 1

• 2

• 3

• 4

Multiple Choice

How many orbitals are on the 3rd energy level?

• 1

• 9

• 12

• 3

Multiple Choice

How many energy levels are on the periodic table

• 3

• 18

• 5

• 7

Multiple Choice

How many electrons can you put in the 2nd Energy Level?

• 2

• 6

• 8

• 18

Multiple Choice

How many sub-levels are in the 4th Energy Level?

• 1

• 2

• 3

• 4

Multiple Choice

How many electrons can fit in the 3rd Energy Level?

• 18

• 8

• 2

• 32

S-block

Experience Chemistry | Lesson 1.5

P-block

Experience Chemistry | Lesson 1.5

d-block

Experience Chemistry | Lesson 1.5

f-block

Experience Chemistry | Lesson 1.5

Electron Configurations​

• Electron Configurations: The way in which electrons are arranged in various orbitals around the nuclei of atoms

  • Electrons fill orbitals following certain rules​

Experience Chemistry | Lesson 1.5

Energy and Stability in Electron Configurations

• Energy plays a major role in how electrons arrange themselves in an atom

• Three rules for Electron Configurations

  • The Aufbau Principle: Electrons occupy the lowest energy sub-shells first​

    • This makes elements more stable

    • the 1s orbitals will always fill before the 2s orbitals

    • Order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p....

      • d sub-shells are always a lower energy level than the rest of the period

    ​

Experience Chemistry | Lesson 1.5

Energy and Stability in Electron Configurations

• Three rules for Electron Configurations

  • Pauli's Exclusion principle: 2 electrons to an orbital. Electrons in the same orbital can not be in the same spot at the same time

    • Spin: a property of electrons that describes their orientation in an orbital

    • We show this with two verticle arrows pointing in opposite directions

Experience Chemistry | Lesson 1.5

Writing Electron Configurations

• Step 1: Use the Atomic number to determine the number of electrons

  • Example: Oxygen​

Experience Chemistry | Lesson 1.5

Multiple Choice

Write the electron configuration for Beryllium

• 1S2S²

• 2S²

• 1S²2s²

• 1s²2S²2P²

Exceptions to Electron Configuration Rules

• Some elements do not follow the normal electron configuration rules that others do

  • Chromium: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁵ 4s¹

  • Copper: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4s¹

Experience Chemistry | Lesson 1.5

Noble Gas Short-Hand Configurations

• Electron Configurations can get long

• You can shorten the writing by starting with the Noble Gas before the element, and only writing what is in the period of the element in questions​

Experience Chemistry | Lesson 1.5

Noble Gas Short-Hand Configurations

• Example: Sulfur​

  • The noble Gas before Sulfur is Ne

  • Shortened Configuration: [Ne] 3s²3p⁴

• Example: Potassium

  • Noble Gas Before Potassium is Argon

    • Shortened Configuration: [Ar] 4s¹​

Experience Chemistry | Lesson 1.5

Multiple Choice

Write the shorthand electron configuration for Ca

• 1S²2S²2P⁶3S²3P⁶4S²

• [Kr]4S²

• [Ar]4S²

• [Ar)2P²

Complete Electron Configuration Worksheet 1

Multiple Choice

What atom matches this electron configuration?

1s²2s²2p⁶3s²3p⁶4s²3d¹⁰

• Zinc

• Copper

• Nickel

• Germanium

Multiple Choice

Identify the Electron Configuration for Aluminum (Al)

• 1s² 2s² 2p⁶ 3s² 3p¹

• 1s² 2s² 2p⁶ 3s² 3p³

• 1s² 2s² 2p⁶ 3s² 4p¹

Multiple Choice

What electron configuration matches an oxygen atom?

• 1s²2s²2p⁶3s2, 3p⁶4s²3d¹⁰4p⁵

• 1s²2s²2p⁴

• 1s²2s²2p⁶

• 1s²2s²2p⁶3s²3p⁶4s²3d¹

Orbital Configuration

the more visual way to represent the arrangement of all the electrons in a particular atom

Each sublevel is labeled by its principal energy level and sublevel

Electrons are indicated by arrows inside the circles. An arrow pointing upwards indicates one spin direction, while a downward pointing arrow indicates the other direction.

Energy and Stability in Electron Configurations

• Three rules for Electron Configurations

  • Hunds Rule: In sub-shells with multiple orbitals (p, d, f), all orbitals must be filled before getting a second electron

    • Every orbital has to get an electron before getting seconds

Experience Chemistry | Lesson 1.5

Multiple Choice

Which element is pictured?

• neon
• fluorine
• magnesium
• argon

Multiple Choice

What element has this orbital notation?

• lithium

• beryllium

• boron

• carbon

Hunds Rule

every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied, and all electrons in singly occupied orbitals have the same spin.

​Electron Orbital Notation Worksheet

Multiple Choice

Valence electrons are: 

• Electrons farthest away from the nucleus
• Electrons closest to the nucleus
• Electrons that just come and go - they don't stay with the atom
• Electrons in the second shell

Multiple Choice

How many valence electrons does Lithium (Li) have?

• 8

• 1

• 5

• 2

​Electron Dot Diagram Worksheet

Multiple Choice

This is a correct dot diagram for neon (Ne)

• true

• false

Multiple Choice

This could be the dot diagram of 

• Ne
• Si
• Al
• Be

Multiple Choice

This could be the dot diagram of

• Mg

• Cl

• C

• O

Multiple Choice

How many VALENCE ELECTRONS does Boron have?

• 3

• 5

• 2

Multiple Choice

How many VALENCE ELECTRONS does Nitrogen have?

• 7

• 5

• 2

Multiple Choice

Which is a CORRECT electron dot diagram for Beryllium?