AP Chemistry The Atom 2015-08-25 www.njctl.org Slide 3 / 113 - PDF document

Slide 1 / 113 Slide 2 / 113 AP Chemistry The Atom 2015-08-25 www.njctl.org Slide 3 / 113 Slide 4 / 113 Table of Contents: The Atom (Pt. B) Click on the topic to go to that section Periodic Table · Periodic Table · Periodic Trends Return to Table of Contents Slide 5 / 113 Slide 6 / 113 Special Groups The Periodic Law Some groups have distinctive properties and are given special names. Alkaline Earth Metals Noble Gases Halogens Alkali Metals Transition Metals Recall that the periodic law states that the physical and chemical properties of the elements tend to recur in a systematic way when arranged by increasing atomic number.

Slide 7 / 113 Slide 8 / 113 1 What is the atomic number for the element in 2 What is the atomic number for the element period 3, group 16? in period 5, group 3? Slide 9 / 113 Slide 10 / 113 3 To which group on the periodic table does Neon 4 To which group on the periodic table does Iron belong? belong? Alkali Metals Alkali Metals A A B Transition Metals B Transition Metals Halogens C Noble Gases C Alkaline Earth Metals D Alkaline Earth Metals D Slide 11 / 113 Slide 12 / 113 5 To which group on the periodic table does 6 Two elements are studied. One with atomic Beryllium belong? number X and one with atomic number X+1. It is known that element X is a Noble Gas. Which A Alkali Metals group on the periodic table is X+1 in? Transition Metals B Transition Metals A Halogens C Halogens B Alkaline Earth Metals D Alkali Metals C There is no way to tell D

Slide 13 / 113 Slide 14 / 113 Periodic Table & Electron Configuration Periodic Table & Electron Configuration 1A 2A 8A 1 2 18 3A 4A 5A 6A 7A 13 14 15 16 17 8B } 3B 4B 5B 6B 7B 1B 2B 3 4 5 6 7 8 9 10 11 12 Click here to view an Interactive Periodic Table that shows orbitals for each Element Click here for an electron orbital game. There are two methods for labeling the groups, the older method shown in black on the top and the newer method shown in blue on the bottom. Slide 15 / 113 Slide 16 / 113 7 The highlighted elements below are in the 8 The highlighted elements below are in the A s block A s block B d block B d block C p block C p block D f block D f block Slide 17 / 113 Slide 18 / 113 9 The highlighted elements below are in the 10 The electron configuration ending ns 2 p 6 belongs in which group of the periodic table A s block A Alkali Metals B d block B Alkaline Earth Metals C Halogens C p block D Noble Gases D f block

Slide 19 / 113 Slide 20 / 113 11 An unknown element has an electron Shorthand Configurations configuration ending in s 2 . It is most likely Noble Gas elements are used to write shortened electron in which group? configurations. A Alkaline Earth Metals To write a Shorthand Configuration for an element: B (1) Write the Symbol of the Noble Gas element from Halogens the row before it in brackets [ ]. C Alkali Metals (2) Add the remaining electrons by starting at the s D Transition Metals orbital of the row that the element is in until the configuration is complete. Slide 21 / 113 Slide 22 / 113 12 What would be the expected "shorthand" electron 13 Which of the following represents an electron configuration for Sulfur (S)? configuration of a Halogen? A [He]3s 2 3p 4 A [He]2s 1 B [Ar]3s 2 4p 4 B [Ne]3s 2 3p 5 C [Ar]4s 2 3d 2 C [Ne]3s 2 3p 3 D [Kr]5s 2 4d 10 5p 4 D [Ne]3s 2 3p 4 Slide 23 / 113 Slide 24 / 113 14 The electron configuration [Ar]4s 2 3d 5 belongs in 15 Which of the following represents an electron which group of the periodic table configuration of an alkaline earth metal? A Alkali Metals A [He]2s 1 B Alkaline Earth Metals B [Ne]3s 2 3p 6 C Transition Metals C [Ar]4s 2 3d 2 D [Xe]6s 2 D Halogens

Slide 25 / 113 Slide 26 / 113 Stability Stability Elements of varying stability fall into one of 3 categories. The most stable atoms have completely full energy levels. When the elements were studied scientists noticed that some of them do not react in certain situations in which others do. These elements ~Full Energy Level were labeled "stable" because they did not change easily. When these ~Full Sublevel (s, p, d, f) stable elements were grouped together, it was noted that periodically, ~Half Full Sublevel ( d 5 , f 7 ) there were patterns in the occurrence of stable elements. 1 Today we recognize that this difference in stability is due to electron 2 configurations. 3 4 5 6 7 6 7 Slide 27 / 113 Slide 28 / 113 Stability Stability Finally, the elements with half full sublevels are also stable, but not as Next in order of stability are elements with full sublevels. stable as elements with fully energy levels or sublevels. ~Full Energy Level ~Full Energy Level ~Full Sublevel (s, p, d, f) ~Full Sublevel (s, p, d, f) ~Half Full Sublevel ( d 5 , f 7 ) ~Half Full Sublevel ( d 5 , f 7 ) 1 1 2 2 3 3 4 4 5 5 6 6 7 7 6 6 7 7 Slide 29 / 113 Slide 30 / 113 16 The elements in the periodic table that 17 Alkaline earth metals are more stable than have completely filled shells or subshells alkali metals because... are referred to as: A they have a full shell. A noble gases. B B they have a full subshell. halogens. C C alkali metals. they have a half-full subshell. D transition elements. D they contain no p orbitals.

Slide 31 / 113 Slide 32 / 113 Electron Configuration Exceptions 18 The elements in the periodic table which lack one electron from a filled shell are referred to as: You should know the basic exceptions in the d- and f-sublevels. A These fall in the circled areas on the table below. noble gases. B halogens. 1 2 C alkali metals. 3 4 D transition elements. 5 6 7 6 7 Slide 33 / 113 Slide 34 / 113 Electron Configuration Exceptions Energies of Orbitals Chromium Expect: [Ar] 4s 2 3d 4 Actually: [Ar] 4s 1 3d 5 Because of how close the f For some elements, in order to exist in a more stable state, electrons 7f and d orbitals are to the s from an s sublevel will move to a d sublevel, thus providing the 7d orbitals an electron very little 6f stability of a half-full sublevel. To see why this can happen we need 7 energy is required to move an 7p 6d to examine how "close" d and s sublevels are. electron from the s orbital 5f 6 7s (leaving it half full) to the f or d 6p 1 5d 4f orbital, causing them to also Energy 5 2 6s 5p be half full. 4d 3 4 5s 4 Cr 4p (It's kind of like borrowing a 3d 5 3 4s cup of sugar from a neighbor. 3p 6 You'd only borrow it from 2 3s 7 someone you were close to 2p 1 and only if you needed it.) 2s 6 7 1s Slide 35 / 113 Slide 36 / 113 19 The electron configuration for Copper (Cu) is Electron Configuration Exceptions A [Ar] 4s 2 4d 9 Copper Expected: [Ar] 4s 2 3d 9 Actual: [Ar] 4s 1 3d 10 B [Ar] 4s 1 4d 9 Copper gains stability when an electron from the 4s C [Ar] 4s 2 3d 9 orbital fills the 3d orbital. D [Ar] 4s 1 3d 10 1 2 3 4 Cu 5 6 7 6 7

Slide 37 / 113 Slide 38 / 113 20 What would be the expected "shorthand" electron 21 What would be the expected "shorthand" electron configuration for Silver (Ag)? configuration for Molybdenum (Mb)? A [Kr]5s 2 5d 9 A [Kr]5s 2 5d 4 B [Ar]5s 1 4d 10 B [Ar]5s 2 4d 4 C [Kr]5s 2 4d 9 C [Kr]5s 1 4d 5 D [Kr]5s 2 4d 4 D [Kr]5s 1 4d 10 Slide 39 / 113 Slide 40 / 113 Periodic Trends There are four main trends in the periodic table: Periodic Trends Size or radius of atoms/ions Electronegativity Ionization energy Metallic character Return to Table of Contents Slide 41 / 113 Slide 42 / 113 Effective Nuclear Charge Periodic Trends In a multi-electron atom, electrons are both attracted to the These four periodic trends are all shaped by the interactions positive nucleus and repelled by other electrons. between the positive charge of the atomic nucleus and the negative charges of electrons. The nuclear charge that an electron experiences depends on both factors. For example, here's sodium. Valence 3s electron - 10- [Ne] inner shell electrons (10-) 11+ Nucleus (11+) Combined effect = 11-10 = 1+