Lesson Objectives Express the arrangement of electrons in atoms using E lectron configurations

1. Lesson Objectives • Express the arrangement of electrons in atoms using • Electron configurations • Lewis valence electron dot structures • Electron Arrangement

2. Heisenberg uncertainty principle – it’s impossible to know the exact velocity and position of a particle at the same time • Atomic orbitals – areas where electrons are likely to be found • Four types of orbitals • s, p, d, and f • Quantum numbers– sets of numbers that describe the properties of atomic orbitals and the electrons in them • Atomic Orbitals s-orbital shape p-orbital shape d-orbital shapes

3. Principle quantum number – (n) represents an atomic orbital’s size and principle energy level • Electrons that are further away from the nucleus have more energy • Electrons in larger orbitals are more likely to be further from the nucleus • Principle Energy Levels n = 2 n = 1 nucleus • Larger orbitals = more E

4. Principle energy levels can be divided into sublevels • Sublevels are labeled using their principle energy level and orbital type • Higher principle energy levels are composed of more sublevels Ex) Principle energy level 1 contains one sublevel Ex) Principle energy level 2 contains two sublevels • Quantum Numbers n Orbital type 1s { Sublevel 2s2p

5. Each s sublevel contains one s-orbital • Each psublevel contains three p-orbitals • Each dsublevel contains five d-orbitals • Each fsublevel contains seven f-orbitals • Sublevel Capacities s sublevel p sublevel dsublevel f sublevel

6. Each orbital can hold up to two electrons • Each s sublevel can hold up to two electrons • Each p sublevel can hold up to six electrons • Each d sublevel can hold up to ten electrons • Each f sublevel can hold up to fourteen electrons • Orbital Capacities s sublevel p sublevel dsublevel f sublevel

7. Electron configuration – describes an atom’s electron arrangement • Systems with lower energy are more stable • Ground-state electron configuration – arrangement of electrons that gives an atom the least possible energy • Three rules govern how electrons are arranged in ground-state electron configurations: • Aufbau principle • Pauli exclusion principle • Hund’s rule • Ground-State Electron Configurations

8. Electrons achieve their ground-state when they occupy the closest available orbital to the nucleus • Aufbau Principle – electrons fill available orbitals with the least energy first • Aufbau diagrams show the order of orbitals from least to greatest energy • Aufbau Principle

9. Periodic Table Blocks

10. Orbital Filling Order

11. Pauli Exclusion Principle • Pauli exclusion principle – each orbital can hold a maximum of two electrons • When in the same orbital electrons must have opposite spin • Direction of the electron’s spin is represented the direction of the arrow

12. Hund’s Rule • Negative charges of electrons repel each other • Hund’srule – when filling equal energy orbitals, electrons fill each orbital singly before filling orbitals with another electron in them 2p Energy 2s 1s

13. Boxes or lines = orbitals • Arrows = electrons • Determine the highest energy sublevel • Draw sublevels in the order they are filled • Determine using periodic blocks • Fill orbitals • Number of electrons equals atomic number Ex) Draw the orbital diagram for oxygen • Drawing Orbital Diagrams 1s 2s 2p

14. Determine the highest energy sublevel of the atom • Write the sublevels in the order they are filled • Determine using periodic blocks • Write the number of electrons in each sublevel as a superscript Ex) Write the electron configuration of iron • Electron Configuration Notation 1s 2s 2p 3s 3p 6 4s 6 3d 6 2 2 2 2

15. Filling Electron Orbitals 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 6f 7s 7p

16. Noble gas notation – short hand version of electron configuration notation • Noble gas of the previous period is written in brackets to represent the electron configuration up to that point • Remainder of the electron configuration is written after the noble gas • Noble Gas Configuration Notation • Ex) Write the noble gas configuration of iron 1s 2s 2p 3s 3p 6 4s 6 3d 2 6 2 2 2 Ar

17. Write the noble gas notation for Iron (Fe)

18. Valence Electrons • Valence Electrons • Valence electrons– electrons found in the highest occupied energy level • Outermost electrons of the electron cloud • Establish the chemical characteristics of elements • Only electrons represented in Lewis electron dot structures • Symbolized by dots

19. Number of valence electrons is the same as the group number of representative elements • Electron Dot Periodic Table

20. Number of valence electrons is the same as the group number of representative elements Ex) Group 5A elements have 5 valence electrons • N is in group 5A • Writing Lewis Electron Dot Structures N

21. Identify the number of valence electrons using the periodic table • Place the corresponding number of electron dots around the symbol • First assign one dot per side • If there are still more dotsto assign, assign a second dot Ex) Dot Structure for Phosphorus • Writing Electron Dot Structures P

22. Ions form when electrons are lost or gained • Ionic charges are based on the number of electrons lost or gained • Losing or gaining electrons changes the ratio of positive particles (p+) to negative particles (e-) and causes an overall charge to form • Valence Electrons and Ion Formation Ex) Na lost 1 e- to become Na+ F gained 1 e- to become F- 10 e- 10 e- 11 p+ 9 p+ + + +1 charge -1 charge

23. Valence Electrons and Ion Formation • Generally, charge can be be determined by an ion’s group number • Metals lose valence electrons to form cations • Nonmetals gain valence electrons to form anions 1+ 3+ 2- 1- 3- 2+

24. Electron Dot Structures for Ions • Excess or deficit of electrons will be represented by • Number of electrons around the symbol • Charge outside the dot structure Ex) Neutral calcium becomes a calcium ion Ca Ex) Neutral sulfur becomes a sulfide ion 2- S