Electron Configuration

Unit 7 opening topic:

Electron Configuration

​describing the organization of the electrons in the electron cloud

Learning Objectives for this Quizizz Lesson

• Determine # of electrons in an atom based on Atomic Number

• Recognize simple electron configurations based on format “#-#-#”

• Locate the electron configuration of an element on the Periodic Table

• Explain electron energy levels (aka “shells”).

• Recall the maximum number of electrons for shells 1, 2, and 3

• Define the term valence electrons

• Identify # of valence e^-s from an electron configuration

Open Periodic Table in a separate tab for quick reference

https://www.sciencegeek.net/tables/NYregents.pdf

(Zoom in using "Ctrl +" , move around screen using arrow keys)

Multiple Choice

Examine the electron configurations of elements in rows 2 and 3 of the Periodic Table...

What seems to be the maximum number of electrons that can go in the first energy level?

• 2

• 4

• 6

• 8

• 18

Multiple Choice

Review question...

An Electron ___________.

• exists outside the nucleus, has a positive charge of 1+ , and has almost no mass

• exists outside the nucleus, has a negative charge of 1- , and has almost no mass

• exists outside the nucleus, has a negative charge of 1- , and has mass of 1 u

Multiple Choice

An atom of nitrogen (N) has how many electrons?

(Hint: the term "atom" implies it has a net charge of zero... # electrons = # protons)

• 6

• 7

• 14

• 15

Nitrogen atoms have 7 electrons

• Atomic Number of 7 (Z = 7)

• if Z = 7 , # protons = 7

• 7 protons means nuclear charge of 7+

• Need 7- to balance the 7+ to be neutral

• each electron has charge of 1-

• Thus, nitrogen atoms have 7 electrons

Electron Configuration

• Describes the organization of atom's electrons into different energy levels

• energy levels are often called "shells"

• number to the far left is nearest the nucleus

• As you read to the right, each digit represents a new energy level that is a greater distance [from nucleus] AND higher energy!

Model of carbon atom showing the electrons in different energy levels

• (electrons are blue spheres in this model)

• Carbon's electron configuration is 2-4

• 2 electrons are shown in the 1st "shell"

• 4 electrons are shown in the 2nd "shell"

• 2nd shell elecrons have higher energy than those in 1st shell

Multiple Choice

Using your Periodic Table, identify the electron configuration of oxygen.

• 2-5

• 2-6

• 2-7

• 2-8

electron configuration of an oxygen atom is 2-6

(8 total electrons; 2 in the 1st energy level ; 6 in the 2nd energy level)

Multiple Choice

Based on the pattern in electron configurations on your Periodic Table, determine the maximum number of electrons that can fit in the first "shell" of an atom.

• 2

• 4

• 6

• 8

• 18

Multiple Choice

Based on the pattern in electron configurations on your Periodic Table, determine the maximum number of electrons that can fit in the 2nd "shell" of an atom.

• 2

• 4

• 6

• 8

• 18

Maximum # of electrons in energy levels 1-3 (shells 1-3)

• Max of 2 e^- in Level 1

• Max of 8 e^- in Level 2

• Max of 18 e^- in Level 3

electrons in the outermost shell are called valence electrons

These are the most important electrons of an atom.

Carbon has electron configuration 2-4. It has 4 valence electrons.

Multiple Choice

How many valence electrons does an atom of chlorine have?

(chemical symbol Cl, atomic number 17)?

• 2

• 8

• 7

• 17

Multiple Choice

How many valence electrons does an atom of fluorine have?

(chemical symbol F, atomic number 9)?

• 2

• 7

• 9

Chlorine and fluorine both have 7 valence electrons

• elements in the same column of PT have the same number of valence electrons.

• This is the other key factor in how the PT is organized.

Learning Objectives revisited...

Can you ... ?

• Determine # of electrons in an atom based on Atomic Number

• Recognize simple electron configurations based on format “#-#-#”

• Locate the electron configuration of an element on the Periodic Table

• Explain electron energy levels (aka “shells”).

• Recall the maximum number of electrons for shells 1, 2, and 3

• Define the term valence electrons & Identify # of valence e^-s

Poll

Rate yourself on a 1 to 4 basis for the objectives on the previous slide.

(1 meaning you are struggling, 4 meaning you could tutor someone since you know it so well)

• 1

• 2

• 3

• 4