Electron Configuration Ch 13

Review 7 energy levels electrons can be found in As the number of electrons increases, you fill more energy levels Each energy level contains certain sublevels that hold a specific number of electrons s (holds 2 electrons), p (6), d (10), f(14)

Electron Configuration Arrangement of electrons in the energy levels and sublevels Always fill the lowest energy sublevel first Use Aufbau principle to correctly fill the energy levels and sublevels in order

Electron Configuration for Sodium How many electrons does Sodium (Na) have? 11 What is the first sublevel electrons fill? 1s How many electrons can fit in the 1s sublevel? 2 What is the second sublevel electrons fill? 2s How many electrons can fit in the 2s sublevel?

What is filled after the 2s sublevel? 2p How many electrons can fit in the 2p sublevel? 6 How many electrons are left that need a sublevel? 2+2+6=10 have been used 1 left over What sublevel does the one electron belong to? 3s

How to write Electron Configurations Write the sublevels in order from least energy to most energy Write the total number of electrons in each sublevel as a superscript off the sublevel Example: Sodium (Na) 1s22s22p63s1

Iron (Fe) How many electrons does Fe have? 26 What is the electron configuration for Fe? 1s22s22p63s23p64s23d6 *Remember the 3d sublevel has more energy than the 4s energy level so you fill the 4s sublevel first.

What element has the electron configuration 1s22s22p63s23p64s23d104p3? If you count the electrons, you can then use that to determine the atomic number and name of the element. Since there are 33 electrons, the element is As

Periodic Table and Electron Configurations periodic table shows periodicity, elements in the same group have similar properties Holds true for electron configurations The last sublevel you fill relates to what group you are in If last sublevel to fill is the s sublevel Element is in groups 1 or 2 p sublevel groups 13-18 d sublevel groups 3-12 f sublevel Element is a lanthanoid or actinoid

Kernel Structure Short hand way to show electron configuration To write a kernel structure Need to know the noble gas that comes before the element you are writing the kernel structure for Example: What is the noble gas that comes before Beryllium (Be)? Helium (He)

Write the symbol of the noble gas within brackets Then follow with the rest of the elements electron configuration Whenever you are writing kernel structures Noble gas is always followed by a s sublevel The period of the element that follows your noble gas will tell you the energy level you are in

Beryllium (Be) Kernel structure [He]2s1 Long hand version: 1s22s1

What is the kernel structure for Selenium (Se)? First, what is the noble gas the period above selenium? Argon What period is Selenium in? 4th Kernel structure for selenium is: [Ar]4s23d104p4

What are the only 2 elements that do not have kernel structures? H and He Because there is no noble gas that precedes them Therefore, always write long hand electron configuration