University:
Winston-Salem Forsyth County Schools
Course:
AP Chemistry
Academic year:

2013
Views:

477

Pages:

24
Author:

lervotikzen

Electron Configurations Wrap Up The Layout of the Periodic Table  Elements in the same families have very similar electron configurations. All Alkali Metals end in s1  All Alkaline Earth Metals end in s2  Different chunks of the Periodic Table all have end in the same subshells  The period number determines the highest shell that is occupied.  Lanthanum, Actinium, Lutetium, Lawrencium  These don’t quite fit into our nice neat blocks  Think of Lanthanum and Actinium being in the f block  Think of Lutetium and Lawrencium being in the d block Losing and Gaining Electrons  Ion – an atom that has gained or lost electrons. O 2− Patterns in Forming Ions  Lots of atoms form ions that allow them to get close to a noble gas electron configuration.  Noble gas configurations are especially stable  Will lose or gain electrons depending on which way it is easier to go. Patterns in Forming Ions  Alkali Metals (Sodium)   Alkaline Earth Metals (Magnesium)   Easiest to lose two electrons Group 13 (Aluminum)   Easiest to lose one electron Easiest to lose three electrons Group 14 (Carbon)    Can go both ways Can lose four electrons or gain four electrons In reality does a variety of different things and is not always predictable Patterns in Forming Ions  Group 15 (Nitrogen)   Chalcogens (Oxygen)   Easiest to gain 2 electrons Halogens (Fluorine)   Easiest to gain 3 electrons Easiest to gain 1 electron Noble Gasses (Neon)  Usually don’t react Chemistry Always has Exceptions! Some elements do not make it to a noble gas configuration.  Ga3+ - is actually 1s22s22p63s23p63d10  Gallium ions do not follow the diagonal line diagram.  Pseudo-noble gas configurations – stable configurations with all occupied subshells completely filled.  Other Examples of Exceptions  Copper Expect 1s22s22p63s23p64s23d9  Actually 1s22s22p63s23p64s13d10  Copper gains stability with a full d-subshell   Chromium Expect 1s22s22p63s23p64s23d4  Actually 1s22s22p63s23p64s13d5  Chromium gains stability with a half-full dsubshell  Transition Metal Ions  Gets complicated because of the d-orbitals  Typically form +2 ions but can have many different charges Stable Electron Configurations  Least stable configuration Partially filled subshell  Half filled subshell  Full subshell  Noble Gas Configuration   Most Stable Configuration Predicting Common Ion Charges  You can predict charges on ions formed from elements close to the Noble Gasses   Groups 1 and 2, and the nonmetals You are unlikely to be able to predict the charge on anything else The Octet “Rule”  Most stable ions have noble gas configurations   Xe = 1s22s22p63s23p64s23d104p65s24d105p6 Usually making the most stable ion leaves 8 electrons in the outermost n shell  For example: 5s2 and 5p6 Valence electrons - the number of electrons in the outermost n shell  Core electrons – non-valence electrons   All d and f electrons are core electrons. Why? Valence Electrons           How many valence electrons does each family have? Group 1 (Alkali Metals) have 1 valence electron Group 2 (Alkaline Earth Metals) have 2 valence electrons. Transition Metals and F-Blocks have 2 valence electrons. Group 13 has 3 valence electrons Group 14 has 4 valence electrons Group 15 has 5 valence electrons Group 16 (Chalcogens) has 6 valence electrons Group 17 (Halogens) has 7 valence electrons Group 18 (Noble Gases) has 8 valence electrons Even More Shorthand  Based on the stability of the noble gas configurations  Noble gas becomes the “core” of the configuration.  Leave the outermost electrons alone because this is where the reactions happen. Condensed Electron Configurations For silicon the electron configuration is normally written 1s22s22p63s23p2  Find the previous noble gas   Put it in brackets in place of the electron configuration of the noble gas. For silicon the previous noble gas is Neon.  Neon’s configurations is 1s22s22p6  Silicon = [Ne] 3s23p2  Condensed Electron Configurations  Antimony, Sb  Mercury, Hg  Fermium, Fm  Darmstadium, Ds, #110 MORE Shorthand? AAAHHH!  Lewis Dot Diagrams – using dots to represent the valence electrons of an atom. Write the symbol of the element in the middle.  Draw dots to represent the valence electrons only.  One side is used to represent the valence s orbital.  Other three sides are used for valence p orbitals.  Must use Hund’s Rule for placing the electrons in p orbitals.  Lewis Dot Diagrams Practice  Potassium  Calcium  Chromium  Gallium Lewis Dot Diagram Practice  Germanium  Arsenic  Selenium  Bromine  Krypton