Electron Configuration PDF

# ELECTRON CONFIGURATION By: Janet Brigida A. Catipon MHS Science 9 Teacher ## OBJECTIVES 1. Define Electron Configuration 2. Discuss the rules in writing electron configuration 3. Write the full and abbreviated electron configuration of the elements from any period of the periodic table. 4. Ill...

# ELECTRON CONFIGURATION By: Janet Brigida A. Catipon MHS Science 9 Teacher ## OBJECTIVES 1. Define Electron Configuration 2. Discuss the rules in writing electron configuration 3. Write the full and abbreviated electron configuration of the elements from any period of the periodic table. 4. Illustrate the orbital diagram for each atom based on their electron configuration ## WHAT DID YOU REMEMBER? 1. How will you describe the location of electrons revolving around the nucleus of an atom? 2. What are quantum numbers? 3. What do these quantum numbers describe? 4. How do we compute for the maximum orbitals per energy level? 5. How do we compute for the maximum number of electrons per energy level? ## WHAT CAN YOU SEE? A picture of a stick figure climbing a ladder. The word "ladder" is written below the picture. ## WHAT CAN YOU SEE? ### Bohr's Model of the Atom - Each orbit was given a number, called the *quantum number*. - Bohr orbits are like steps of a ladder, each at a specific distance from the nucleus and each at a specific energy. A depiction of a ladder with levels numbered from 1 to 6. ## ELECTRONIC CONFIGURATION OF AN ATOM - the arrangement of electrons in the orbital of an atom. - described by - a number that designates the number of principal shell - a letter that designates the subshell (orbital) - a subscript that designates the number of electrons in that particular subshell (orbital) **Example:** 2p4 indicates 4 electrons in the p subshell of the 2nd shell. 3d8 indicates 8 electrons in the d subshell of the 3rd shell. ## RULES FOR ELECTRON CONFIGURATIONS - In order to write an electron configuration, we need to know the rules. - 3 rules govern electron configurations. - Aufbau Principle - Pauli Exclusion Principle - Hund's Rule - Using the orbital filling diagram at the right will help you figure out HOW to write them - Start with the 1s orbital. Fill each orbital completely and then go to the next one, until all of the elements have been accounted for. A diagram showing the order in which the orbitals are filled: ``` FOLLOW THE YELLOW BRICK ROAD.. 1s2 START HERE 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 5f14 6s2 6p6 6d10 7s2 7p6 ``` ## a. AUFBAU (BUILDING-UP) PRINCIPLE "Electrons in an atom occupy first the lowest possible energy levels and/or orbitals." **Order:** 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p ## NO MORE THAN 2 ELECTRONS IN ANY ORBITAL...EVER. - The next rule is the **Pauli Exclusion Principle**: - "No two electrons in the same atom can have the same set of four quantum numbers, i.e., the maximum number of electron in an orbital is limited to two." - The spins have to be paired. - We usually represent this with an up arrow and a down arrow. - Since there is only 1 s orbital per energy level, only 2 electrons fill that orbital. *Quantum numbers describe an electrons position, and no 2 electrons can have the exact same quantum numbers. Because of that, electrons must have opposite spins from each other in order to "share" the same orbital.* ## b. PAULI'S EXCLUSION PRINCIPLE *For 1s orbital: Max electron = 2* one electron: n=1, I=0, ml=0,ms=+1/2 one electron: n=1, I=0, ml=0,ms=-1/2 ## HUND'S RULE - Hunds Rule states that when you get to degenerate orbitals, you fill them all half way first, and then you start pairing up the electrons. - **What are degenerate orbitals?** - Degenerate means they have the same energy. - So, the 3 p orbitals on each level are degenerate, because they all have the same energy. - Similarly, the d and f orbitals are degenerate too. **Diagrams showing the orbital filling for Carbon, Nitrogen and Oxygen:** - **Carbon:** ``` NN↑↑ 1s 23 2p Orbital diagram for carbon ``` - **Nitrogen:** ``` 13 25 2p Orbital diagram for nitrogen ``` - **Oxygen:** ``` 15 2p Orbital diagram for oxygen ``` *Don't pair up the 2p electrons until all 3 orbitals are half full.* ## EXCEPTION TO THE RULE - There are two main exceptions to electron configuration: chromium and copper. - In these cases, a completely full or half full d sub-level is more stable than a partially filled d sub-level, so an electron from the 4s orbital is excited and rises to a 3d orbital. ## ARRANGEMENT OF ELECTRONS IN THE ATOMS OF THE FIRST 10 ELEMENTS A table shows the number of electrons in each orbital for the elements H-Ne. - **H = 1s¹** - **He = 1s²** - **Li = 1s2 2s¹** - **Be = 1s2 2s²** - **B = 1s2 2s² 2p¹** - **C = 1s2 2s² 2p²** - **N = 1s2 2s² 2p³** - **O = 1s2 2s² 2p⁴** - **F = 1s2 2s² 2p⁵** - **Ne = 1s2 2s² 2p⁶** A diagram shows the orbital filling for the first 10 elements, with 1s, 2s and 2p orbitals. ## SAMPLE PROBLEM Determining Electron Configuration **PROBLEM**: Using the periodic table give the full and condensed electrons configurations, partial orbital diagrams showing valence electrons, and number of inner electrons for the following elements: **(a) potassium (K: Z = 19)** **(b) molybdenum (Mo: Z = 42)** **(c) lead (Pb: Z = 82)** **PLAN**: Use the atomic number for the number of electrons and the periodic table for the order of filling for electron orbitals. Condensed configurations consist of the preceding noble gas and outer electrons. **SOLUTION**: * **(a) for K (Z = 19)** - **full configuration**: 1s22s22p63s23p64s1 - **condensed configuration**: [Ar] 4s¹ - **partial orbital diagram**: ``` There are 18 inner electrons. ☐ 4s1 3d 4p ``` * **(b) for Mo (Z = 42)** - **full configuration**: 1s22s22p63s23p64s23d104p65s14d5 - **condensed configuration**: [Kr] 5s14d5 - **partial orbital diagram**: ``` There are 36 inner electrons and 6 valence electrons. 5s1 4d5 5p ``` * **(c) for Pb (Z = 82)** - **full configuration**: 1s22s22p63s23p64s²3d104p65s24d105p6s24f145d106p2 - **condensed configuration**: [Xe] 6s24f145d106p2 - **partial orbital diagram**: ``` There are 78 inner electrons and 4 valence electrons. 6s2 6p2 ``` ## ACTIVITY a. Write the expanded/full electron configurations of the following elements: -1) Calcium -2) potassium b. Write the abbreviated electron configurations of the following elements: -3) Aluminum -4) Copper c. Illustrate the orbital diagram of Rubidium (Rb) ## ASSESSMENT 1. Write the electron configurations (FULL & ABBREVIATED) of each of the following atoms: - 1. Scandium - 2. Gallium 2. Determine what elements are denoted by the following electron configurations: - 3. [Kr] 5s24d105p3 - 4. [Xe] 6s24f145d6 c. Illustrate the orbital diagram for number #4. ## Words to live by..... "We should rather be an ELECTRON so that we may able absorb and release energy to be a good and useful particle moving around the earth..." -Yours truly-