Name: Period: Date: UNIT 3: Electrons Lesson 4: The Octet Rule Do Now: By the end of today, you will have an answer to: What role do valence electrons play in chemical changes? Draw the following lewis dot diagrams. Nitrogen Neon Carbon He List two elements that have similar chemical properties to Fluorine. Explain your answer. THINK ABOUT IT!!! Potassium atom Potassium is the eighth most abundant element on the earth, but it is never found free in nature. Draw the lewis dot diagram for potassium (K). Number of protons: Number of neutrons: Number of electrons: Electron Configuration: Potassium Ion Potassium ions are necessary for the function of all living cells. Here is the Lewis dot diagram for potassium ion (K + ). Number of protons: 19 Number of neutrons: 20 Number of electrons: 18 [K] + Electron Configuration: 2-8- 8 COMPARE AND CONTRAST: How are potassium atoms different from potassium ions? THINK ABOUT IT: A potassium ion (K 1+ ) has a +1 charge. Explain, in terms of subatomic particles why it has a charge of +1.
The Octet Rule: Every element wants eight valence electronsa full valence electron shell. Noble Gases (Group 18) are the most stable atoms. Why is this statement true based on the octet rule? Formation of Ions: What happens to an atom that does not have a full octet? IONIZATION ENERGY (definition): Example: 1. From which of these atoms in the ground state can a valence electron be removed using the least amount of energy? (1) Nitrogen (2) Carbon (3) Oxygen (4) Chlorine GIVE IT A TRY! Determine the number of electrons needed to fulfill the octet rule. Circle whether it is easier to gain or lose electrons. Na O N Si Ne F THINK and WRITE: Why does it make sense that sodium has a lower ionization energy than carbon?
Net Charge: How does an atom of an element differ from an ion of that same element? Vocabulary Definition Examples Ion Anion Cation In terms of the number of subatomic particles, what does it mean if an ion has a positive charge? A negative charge? ATOM CATION (POSITIVE CHARGE) ANION (NEGATIVE CHARGE) Example: What ion will the following atom form? 1. How many protons does this atom have? 2. How many electrons does this atom have? 3. How many electrons does this atom need gain or lose in order to fulfill a full octet? Gain: Lose: 4. What is the electron configuration of the Li ion? 5. What is the charge of this ion? 6. Which noble gas configuration does the Li ion have? SUMMARIZING QUESTIONS: 1. How is an ion different from an atom? 2. What is the charge of a calcium ion? 3. What does it mean if an ion has a negative charge?
Name: Pd: Date: CW 3.4- Ions 10 points Calcium atom: ion: Charge of protons: Charge of electrons: Charge of the ion: Berylium atom: ion: Charge of protons: Charge of electrons: Charge of the ion: Regents Practice 1. Which symbol represents a particle with a total of 10 electrons? (1) N (2) N 3+ (3) Al (4) Al 3+ 2. What is the total number of electrons found in an atom of sulfur? (1) 6 (2) 8 (3) 16 (4) 32 3. What is the net charge on an ion that has 9 protons, 11 neutrons, and 10 electrons? (1) 1+ (2) 2+ (3) 1- (4) 2-4. How many electrons are in an Fe 2+ ion? (1) 24 (2) 26 (3) 28 (4) 56 5. Which electron configuration is correct for a sodium ion? (1) 2 7 (2) 2 8 (3) 2 8 1 (4) 2 8 2 6. Compared to a calcium atom, the calcium ion Bromine atom: ion: Charge of protons: Charge of electrons: Charge of the ion: Ca 2+ has (1) more protons (2) fewer protons (3) more electrons (4) fewer electrons Sulfur atom: ion: Charge of protons: Charge of electrons: Charge of the ion: 7. Which atom in the ground state requires the least amount of energy to remove its valence electron? (1) Lithium atom (2) Potassium atom (3) Rubidium atom (4) Sodium atom 8. Which particle has the same electron configuration as a potassium ion? (1) Fluoride ion (2) Sodium ion (3) Neon atom (4) Argon atom 9. An atom of argon rarely bonds to an atom of another element because an argon atom has (1) 8 valence electrons (2) 2 electrons in the first shell (3) 3 electron shells (4) 22 neutrons 10. Which ion has the same electron configuration as an atom of He? (1) H - (2) O 2- (3) Na + (4) Ca +
11. Which set of symbols represents atoms with valence electrons in the same electron shell? (1) Ba, Br, Bi (2) Sr, Sn, I (3) O, S, Te (4) Mn, Hg, Cu 12. When metals form ions, they tend to do so by (1) losing electrons and forming positive ions (2) losing electrons and forming negative ions (3) gaining electrons and forming positive ions (4) gaining electrons and forming negative ions Free Response Practice 13. Explain, in terms of electron configuration, why an oxygen ion is more stable than an oxygen atom. Use the information below to answer questions 14 and 15. In a chemical reaction, Zn changes to become Zn +2. 14. State what happens to the number of protons in a Zn atom when it changes to Zn 2+ in this reaction. 15. State what happens to the number of electrons in a Zn atom when it changes to Zn 2+ as the redox reaction occurs.
Name: Pd: Date: HW 3.4- Ions 10 points REVIEW HW: 1. How many electrons are contained in an Au 3+ ion? (1) 76 (3) 82 (2) 79 (4) 197 4. Which Lewis electron- dot diagram is correct for a S 2- ion? 2. Which two particles make up most of the mass of a hydrogen- 2 atom? (1) Electron and neutron (2) Electron and proton (3) Proton and neutron (4) Proton and positron 3. Which statement explains why sulfur is classified as a Group 16 element? (1) A sulfur atom has 6 valence electrons (2) A sulfur atom has 16 neutrons. (3) Sulfur is a yellow solid at STP. (4) Sulfur reacts with most metals. 5. Write an electron configuration for an atom of aluminum- 27 in an excited state. Name: Pd: Date: HW 3.4- Ions 10 points REVIEW HW: 1. How many electrons are contained in an Au 3+ ion? (3) 76 (3) 82 (4) 79 (4) 197 4. Which Lewis electron- dot diagram is correct for a S 2- ion? 2. Which two particles make up most of the mass of a hydrogen- 2 atom? (5) Electron and neutron (6) Electron and proton (7) Proton and neutron (8) Proton and positron 3. Which statement explains why sulfur is classified as a Group 16 element? (5) A sulfur atom has 6 valence electrons (6) A sulfur atom has 16 neutrons. (7) Sulfur is a yellow solid at STP. (8) Sulfur reacts with most metals. 5. Write an electron configuration for an atom of aluminum- 27 in an excited state.
6. Draw a Lewis electron- dot diagram for an atom of boron. [1] 7. Explain, in terms of atomic structure, why the noble gas is an unreactive element. [1] Base your answers to questions 8 through 10 on the information below. Elements with atomic numbers 112 and 114 have been produced and their IUPAC names are pending approval. However, an element that would be put between these two elements on the Periodic Table has not yet been produced. If produced, this element will be identified by the symbol Uut until an IUPAC name is approved. 8. Draw a Lewis electron- dot diagram for an atom of Uut. 9. Determine the charge of an Uut nucleus. Your response must include both the numerical value and the sign of the charge. 10. Identify one element that would be chemically similar to Uut. 6. Draw a Lewis electron- dot diagram for an atom of boron. [1] 7. Explain, in terms of atomic structure, why the noble gas is an unreactive element. [1] Base your answers to questions 8 through 10 on the information below. Elements with atomic numbers 112 and 114 have been produced and their IUPAC names are pending approval. However, an element that would be put between these two elements on the Periodic Table has not yet been produced. If produced, this element will be identified by the symbol Uut until an IUPAC name is approved. 8. Draw a Lewis electron- dot diagram for an atom of Uut. 9. Determine the charge of an Uut nucleus. Your response must include both the numerical value and the sign of the charge. 10. Identify one element that would be chemically similar to Uut.
Name: Pd: Date: Exit Ticket Quiz 3.4- Ions 4 points 1. What is the difference between an atom and an ion? 2. What is the total number of electrons in a Cr 3+ ion? (1) 18 (2) 21 (3) 24 (4) 27 3. Which species does not have a noble gas electron configuration? (1) Na + (2) Mg 2+ (3) Ar (4) S Name: Pd: Date: Exit Ticket Quiz 3.4- Ions 4 points 1. What is the difference between an atom and an ion? 2. What is the total number of electrons in a Cr 3+ ion? (1) 18 (2) 21 (3) 24 (4) 27 3. Which species does not have a noble gas electron configuration? (1) Na + (2) Mg 2+ (3) Ar (4) S