Today’s Do Now 9/11/2014 You will need 4 different colors of writing utensils today – please take these out and have them on your desk 1. Which of the following scientist(s)’ models of the atom contained electrons in a uniform, homogenous background of positive charge? A. Thomson B. Moseley C. Rutherford D. Bohr E. A and C 2. How did Bohr’s model of the atom differ from Rutherford’s model? A. The presence of negatively charged electrons B. A positively charged nucleus that is small and dense C. Electrons embedded within positively charged material D. Electrons only located in quantized energy levels E. None of the above 3. Pick two experiments pivotal to the understanding of the atom and describe a similarity between the two experiments and describe the most important observations from each one.

Electron Configurations 1s 2 2s 2 2p 6 …….

Today’s Game Plan Do Now 10 minutes Electron Configurations 35 minutes Other Ways to Represent Electrons 10 minutes Guided Practice 15 minutes Homework and Closing 10 minutes

Last class…  Electrons exist in quantized energy levels

Last class… # of # of Shape orbitals electrons s 1 2 p 3 6 d 5 10 f 7 14 # of # of Shape orbitals electrons s 1 2 p 3 6 d 5 10 f 7 14 In each energy level, multiple shapes may exist

Orbitals in the first two energy levels.

Electron Configuration  Electron configuration is the arrangement of electrons in an atom.  The electron configuration of an atom is written by stating the number of electrons in each energy subshell and writing the subshells in order of increasing energy.

Aufbau Principle  An electron occupies the lowest- energy orbital that can receive it

Hydrogen…where do we put the electron?

Pauli Exclusion Principle  An atomic orbital can hold a maximum of 2 electrons and those 2 electrons must have opposite spins

Hund’s Rule  Electrons will fill sublevels of equal energy value one at a time before doubling up Do you ever double up on the bus before you have to???

Hund’s Rule 1s2s 2p Oxygen Electron Box Configuration

Hund’s Rule

 The s block is two boxes wide, and the s subshell holds a maximum of 2 electrons.  The p block is 6 boxes wide, which represents the 6 electrons that the p subshell can hold.  The d block is 10 boxes wide, which represent the 10 electrons that the d subshell can hold.  The f block has 14 boxes, which represent the 14 electrons that the f subshell can hold.

 The s and p blocks keep their row/period numbers, while the d block is the row number minus 1 (period # - 1) and the f block is the row number minus 2 (period # - 2)  Example: The fourth period has 3d, not 4d.

Using the Periodic Table to determine electron configuration 1. Determine the location of the element on the Periodic Table. 2. List and “fill in” orbitals by following the Periodic Table until you reach the desired element. 3. Add all the numbers of electrons in the electron configuration to make sure that it matches the number of electrons for the atom.

Carbon e e e e 1s 2 2s 2 2p e e e e e e e e 2

Example: Sulfur 1. Locate sulfur on the Periodic Table. It is in the third period, in the p block of elements. (Indicated in red below) 2. In order to reach sulfur, following the Periodic Table, you first have to fill 2 electrons in the 1s.( Each “box” represents an electron.) Then, 2 electrons would fill in the 2s subshell, then 6 electrons in 2p, then 2 electrons in 3s, and finally there would be 4 electrons to fill the 3p subshell. 3. Therefore, the electron configuration would be: 1s 2 2s 2 2p 6 3s 2 3p 4

Calcium & Magnesium Ca: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 Mg: 1s 2 2s 2 2p 6 3s 2

Practice Write the electron configuration of the following elements: 1. Na 2. Mn 3. P 4. He 5. Kr Bonus: Ra

Today’s Game Plan Do Now 10 minutes Electron Configurations 35 minutes Other Ways to Represent Electrons 10 minutes Guided Practice 15 minutes Homework and Closing 10 minutes

Noble Gas Notation  An even shorter way of writing electron configuration  ONLY uses NOBLE GASES (Group 18 elements)

Electron Configuration of Noble Gases  Write the electron configuration for the following elements: 1. Helium 2. Neon 3. Argon 4. Krypton

Electron Configuration of Noble Gases  Write the electron configuration for the following elements: 1. Helium - 1s 2 2. Neon - 1s 2 2s 2 2p 6 3. Argon - 1s 2 2s 2 2p 6 3s 2 3p 6 4. Krypton - 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6

Noble Gas Notation Helium - 1s 2 Carbon - 1s 2 2s 2 2p 2 Carbon: [He]2s 2 2p 2

Noble Gas Notation Sulfur - 1s 2 2s 2 2p 6 3s 2 3p 4 Which the noble gas configurations (Helium, Neon, Argon, Krypton) is highlighted in orange?  Neon!! Sulfur – [Ne]3s 2 3p 4

Calcium & Magnesium Noble Gas Notation Ca: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 Mg: 1s 2 2s 2 2p 6 3s 2 Ca: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 [Ar]4s 2 Mg: 1s 2 2s 2 2p 6 3s 2 [Ne]3s 2

Lewis Dot Structures  A drawn representation of an atom that shows the valence electrons

How do I draw a Lewis Dot Structure? 1. Write the symbol of the element 2. Find out how many valence electrons the element has 3. Place dots on the four sides of the symbol one at a time

Class Example #1  Draw a Lewis Dot Diagram of Sulfur

Today’s Game Plan Do Now 10 minutes Electron Configurations 35 minutes Other Ways to Represent Electrons 10 minutes Guided Practice 15 minutes Homework and Closing 10 minutes

Guided Practice  Horse Races!! Everyone starts with 5 points…if my expectations are not met we will enter into silent practice.

Write the electron configuration for Chlorine 1s 2 2s 2 2p 6 3s 2 3p 5

Write the Noble Gas configuration for Chlorine [Ne] 3s 2 3p 5

 Draw a Lewis Dot Diagram of Calcium

Draw the electron configuration for Na 1s 2 2s 2 2p 6 3s 1

Draw the electron configuration for Iron 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 6

Draw the Noble Gas configuration for Iron [Ar] 4s 2 3d 6

 Draw a Lewis Dot Diagram of Oxygen

Write the electron configuration for Bromine 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5

Write the Noble Gas configuration for Bromine [Ar] 4s 2 3d 10 4p 5

Today’s Game Plan Do Now 10 minutes Electron Configurations 35 minutes Other Ways to Represent Electrons 10 minutes Guided Practice 15 minutes Homework and Closing 10 minutes

Today’s Practice and Homework  Electron Configuration Worksheet