Trends Review History of the Periodic Table Oxidation

Trends Review, History of the Periodic Table, Oxidation Numbers

• Objective – Today I will be able to: • Apply the trends of ionization energy, electronegativity and atomic radius to problem solving. • Explain the history of the periodic table. • Identify the oxidation numbers for the families of elements on the periodic table. • Evaluation/ Assessment – Informal assessment – Listening to group interactions and discussions as they complete the analyzing the periodic trends graphing activity – Formal Assessment – Analyzing student responses to the exit ticket, graphs and periodicity practice • Common Core Connection – – Build Strong Content Knowledge Value Evidence Reason abstractly and quantitatively Look for and make use of structure

Lesson Sequence • Warm – Up • Evaluate: Review Chapter 5 worksheet • Informal assessment • Elaborate: Periodicity Practice – Formal assessment • Explain: history of the periodic table and oxidation numbers • Elaborate: Practice and Exam Review – Informal Assessment • Evaluate: Exit ticket • Formal assessment

Warm - Up • What is ionization energy? – How does it change down a family? • Why does this trend occur? – How does atomic radius change across a period? • Why does this trend occur? • How does an atomic radius compare to an ionic radius?

Objective • Today I will be able to: • Apply the trends of ionization energy, electronegativity and atomic radius to problem solving. • Explain the history of the periodic table. • Identify the oxidation numbers for the families of elements on the periodic table.

Homework • Periodic Table (mini-exam) on Thursday and Friday next week • STEM Fair – Final Research Paper due Monday December 17 – In Class Presentations Wednesday January 23

Agenda • • Warm – Up Study guide Review Homework Periodicity Practice Worksheet History of the Periodic Table Notes Oxidation Number Notes Exam Review Exit ticket

Review HW – Chapter 5 Worksheet Discuss answers to selected problems and then turn in

Periodicity Practice Complete Worksheet and Review as a class

History of the Periodic Table and Oxidation Number Notes

Johann Dobereiner (1829) • Law of Triads - in triads of elements the middle element has properties that are an average of the other two members when ordered by the atomic weight • Example - halogen triad composed of chlorine, bromine, and iodine

John Newlands (1864) • Law of Octaves - states that any given element will exhibit analogous behavior to the eighth element following it in the periodic table

Dmitri Mendeleev (1871) • Developed the first Periodic Table • He arranged his table so that elements in the same column (groups) have similar properties; increasing atomic mass

Dmitri Mendeleev (1871) • • • Broke the trend of arranging elements solely by their atomic mass Wanted to keep elements with similar properties in the same columns Left gaps in his early tables; predicted elements that had not been discovered would fill in those gaps - Ekasilicon Germanium - Germanium was discovered in 1886

Dmitri Mendeleev (1871)

Henry Moseley (1913) • Found a relationship between an element’s X-ray wavelength and it’s atomic number (number of protons) • Periodic Law - when elements are arranged in order of increasing atomic number, their physical and chemical properties show a periodic (repeating) pattern • The periodic law is the basis for arranging elements in the periodic table

Glenn Seaborg • He reconfigured the periodic table by placing the actinide series below the lanthanide series • Awarded a Nobel Prize in 1951 • Element 106, Seaborgium (Sg), is named in his honor

Oxidation Numbers

Oxidation Numbers • Remember, most atoms strive to have eight valence electrons (some are satisfied with only two) • Atoms will form various bonds by gaining, losing, or sharing electrons, in order to satisfy the Octet Rule

Oxidation Numbers • An atom’s electron configuration is used to determine how many electrons need to be gained, lost, or shared • Example – Na (11 electrons) • 1 s 2 2 p 6 3 s 1 – 1 valence electron • In order for Na to have eight valence electrons, would it be easier for it to gain 7 electrons, or lose 1? • Losing 1 is easier

Oxidation Numbers • When Na loses an electron it becomes an Na+1 ion • 1 s 2 2 p 6 3 s 1 becomes… • 1 s 2 2 p 6 – 8 valence electrons • Na carries a +1 charge because it has lost an electron, and it now has more positively charged protons than negatively charged electrons

Oxidation Numbers • Another Example – Fluorine (9 electrons) • 1 s 2 2 p 5 – 7 valence electrons • In order for F to have eight valence electrons, would it be easier for it to gain 1 electron, or lose 7? • Gaining 1 is easier

Oxidation Numbers • • When F gains an electron it becomes an F-1 ion 1 s 2 2 p 5 becomes… 1 s 2 2 p 6 – 8 valence electrons F carries a -1 charge because it has gained an electron, and it now has more negatively charged electrons than positively charged protons

Oxidation Numbers • There is a fairly consistent pattern to oxidation numbers with families • Transition Metals and Inner Transition Metals usually have a varying number of valence electrons • Some don’t – Zn+2, Cd+2, Sc+2, Ag+1

Exam Review Complete with the people in your row. If you have questions please ask Ms. Ose

Exit Ticket • Which element is more likely to have a higher (more negative) electron affinity, Aluminum or Sulfur? • List the oxidation number for the following families – Alkali metals – Alkaline earth metals – Halogens – Noble Gases