Lesson plan 6 Wednesday PDF

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CHEM 1A - Week 6 Wednesday (November 6, 2019) Lesson Plan for Professor Arasasingham with LARC Leader: Shania Day

LEARNING GOAL: Students will be able to rank atoms and ions in order or decreasing or increasing atomic/ ionic radii and ionization energies. While recognizing the trend on the periodic table. This will be done by working in table groups to brainstorm patterns and solve practice problems.

ICEBREAKER: Take 5 minutes to go around, say your name, year, major and one thing you did this weekend.

Guided Practice: 1. Atomic vs. Ionic Radius Volume occupied by an atom vs. volume occupied by an ion and the size of an atom is the volume of an electron. 2. What is the periodic trend for size and effective nuclear charge? Explain. Size decreasing going to the right across a row and increases going down a column due to the n increasing. The effective nuclear charge trend is the exact opposite, so it increases going to the right and decreases going down a column. Effective nuclear charge increases because the number of electrons increase as well as the number of protons and the charge felt by the electrons is larger since they are now closer to the nucleus. 3. In terms of Ionic Radius, metals tend to _________ electrons to make __________

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while nonmetals tend to _________ electrons to make ___________ Lose electrons to make cations where the charge corresponds to their group number. Gain electrons to make anions where the charge corresponds to their group number - 8 electrons. 4. How do electron- electron repulsions impact the size of an atom? More electron- electron repulsions increase the size of the electron cloud therefore, increasing the size of the atom.  5. What does it mean when ions are Isoelectronic? Can you think of an example? Ions with the same number of electrons and the same electron configuration (Na+ and Mg2+)  6. Why are anions always bigger than their parent atoms? More electron- electron repulsions that cause the atom size to increase.  7. When ranking anions and cations which one is larger and why? Anions are always larger than cations, bigger the - charge, the bigger the atom, bigger the + charge, smaller the atom.  8. If Ionization energy is the energy required to remove an electron from the electron cloud is it endothermic or exothermic? What are the units? What is the periodic trend for ionization energy? Endothermic (+) in kJ/ mol or MJ/ mol and it increases to the right across a row and going up a column  9. Explain the First Ionization Energy trend and it’s exceptions B and O. Since the size is decreasing then the electrons are being held closer to the nucleus 

making it harder for the electrons to be removed, valence electrons are easier to remove than core electrons. Which is why group 1A elements have the lowest ionization energies and group 8A have the highest ionization energies. The exceptions B and O exist because it is more stable/ highly favored when an electron is removed from them than their corresponding elements Be and N. which are have either half or fully filled orbital diagrams in their natural state. 

G  roup Practice: 1. Which pair of elements would you expect to have the most similar atomic radii, and why? a. Si and Ga Ga is larger than Si b. Si and Ge Ge is larger than Si c. Si and As Most similar in size  2. Choose the larger atom in each pair. a. Sn or Si Sn b. Br or Ga Ga c. Sn or Bi Unable to tell from trend alone d. Se or Sn Sn

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3. Arrange these elements in order of decreasing atomic radius: Cs, Sb, S, Pb, Se. Cs > Pb > Sb > Se > S  4. Write orbital diagrams for each ion and determine if the ion is diamagnetic or paramagnetic. a. Cd2+ Diamagnetic b. Au+ Diamagnetic c. Mo3+ Paramagnetic d. Zr2+ Paramagnetic  5. Which is the larger species in each pair? a. Sr or Sr2+ Sr b. N or N3- N3- c. Ni or Ni2+ Ni d. S2- or Ca2+ S2-

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6. Arrange this isoelectronic series in order of increasing atomic radius: Se2-, Kr, Sr2+, Rb+, Br-. Sr2+ < Rb+ < Kr < Br - < Se2-  7. Choose the element with the higher first ionization energy in each pair. a. P or I Unable to tell from trend alone b. Si or Cl Cl c. P or Sb P d. Ga or Ge Ge 8. Arrange these elements in order of decreasing first ionization energy: Cl, S, Sn, Pb. Cl > S > Sn > Pb 

Independent Practice: Use this time to fill out the second tab of your flipbook, making sure to look for constants, formulas, important concepts that were emphasized on the exam, and any practice problems that were embedded in lecture.

ACTIVITY Write down any questions you still have and post them to the discussion board on canvas

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to allow fellow students to answer them.

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