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)• 1s2 2s2 2p6 3s1 – 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
• 1s2 2s2 2p6 3s1 becomes…• 1s2 2s2 2p6 – 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)• 1s2 2s2 2p5 – 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• 1s2 2s2 2p5 becomes…• 1s2 2s2 2p6 – 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