Section 7 iclicker questions

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1 Reading assignment: As you read ask yourself: What is meant by the expression effective nuclear charge? How can you use this concept to explain the trends in atomic radius in the periodic table? How can you use effective nuclear charge and electron configuration to predict what happens to the radius when ions are formed? Why is the second ionization energy always greater than the first ionization energy? What types of elements have the highest ionization energies and what types have the lowest ionization energies? Why can electron affinity values be both positive and negative? smallest atoms Summary: easy to form negative ions easy to form positive ions largest atoms 1

2 A. The order of atomic masses on the periodic table is in no way related to atomic numbers. B. The atomic number depends on the number of protons in the nucleus, while the atomic weight depends on the number of both protons and neutrons in the nucleus. C. Atomic masses are a function of group numbers on the periodic table and do not increase linearly with atomic number. D. For certain midperiodic table elements, the effective mass of each proton in the nucleus varies. A. The order of atomic masses on the periodic table is in no way related to atomic numbers. B. The atomic number depends on the number of protons in the nucleus, while the atomic weight depends on the number of both protons and neutrons in the nucleus. C. Atomic masses are a function of group numbers on the periodic table and do not increase linearly with atomic number. D. For certain midperiodic table elements, the effective mass of each proton in the nucleus varies. 2

3 In an germanium atom, which electron will experience the greatest effective nuclear charge (Z eff )? An electron in a A) 2s orbital B) 2p orbital C) 3s orbital D) 3p orbital E) 3d orbital In an germanium atom, which electron will experience the greatest effective nuclear charge (Z eff )? An electron in a 2s orbital 2p orbital 3s orbital 3p orbital 3d orbital Ge is 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 2 or [Ar]4s 2 3d 10 4p 2 Z is 32 and S increases as we move to orbitals that are further out. Z eff = Z-S, and therefore 2s has the greatest Z eff 3

4 In an nickel atom, which electron will experience the greatest effective nuclear charge (Z eff )? An electron in a A) 2s orbital B) 2p orbital C) 3s orbital D) 3d orbital In an nickel atom, which electron will experience the greatest effective nuclear charge (Z eff )? An electron in a 2s orbital 2p orbital 3s orbital 3d orbital Ni is 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 8 or [Ar]3d 8 4s 2 Z is 28 and S increases as we move to orbitals that are further out. Z eff = Z-S, and therefore 2s has the greatest Z eff 4

5 What determines the effective nuclear charge on a valence electron? A) The atomic number (number of protons) B) The atomic number and the number of electrons in the core shells. C) The atomic number, the number of electrons in the core shells, the number of electrons in the valence shell. D) The atomic number, the number of electrons in the core shells, the number of electrons in the valence shell and the distance from the nucleus. What determines the effective nuclear charge (Zeff) on a valence electron? C) The atomic number (Z=attraction to nucleus), the number of electrons in the core shells (S=effective shielding, each electron shields for almost 1), the number of electrons in the valence shell (S=contributes, each electron shields for less than 1 (0.35)). D) The atomic number, the number of electrons in the core shells, the number of electrons in the valence shell and the distance from the nucleus. This gives the total attractive force of the electron to the nucleus. 5

6 What is the electron configuration of S? When done identify and count the core electron and valence electrons (next question). A) 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 2 or [Ar]4s 2 4p 2 B) 1s 2 2s 2 2p 4 [He] 2s 2 2p 4 C) 1s 2 2s 2 2p 6 3s 2 3p 4 or [Ar] 3s 2 3p 4 D) 1s 2 2s 2 2p 6 3s 2 3p 6 E) 1s 2 2s 2 2p 6 3s 2 3p 4 or [Ne] 3s 2 3p 4 What are the core and valence electrons of S ( 1s 2 2s 2 2p 6 3s 2 3p 4 or [Ne] 3s 2 3p 4 ) A) 1s 2 2s 2 2p 6 are core (10 total) 3s 2 3p 4 are valence B) 1s 2 2s 2 2p 6 3s 2 (12 total) are core 3p 4 are valence C) 1s 2 2s 2 2p 6 3s 2 3p 3 (15 total) are core 3s 2 3p 1 is valence 6

7 What is the S (shielding value) used to calculate Zeff of the valence electrons in sodium (1s 2 2s 2 2p 6 are core (10 total) 3s 1 are valence) A) Exactly 10 B) Less than 10 C) More than 10 D) Can t tell without Slater s rules calculations What is the S (shielding value) used to calculate Zeff of the valence electrons in sodium (1s 2 2s 2 2p 6 are core (10 total) 3s 1 are valence) A) Exactly 10 B) Less than 10 C) More than 10 D) Can t tell without Slater s rules calculations 7

8 What is the S (shielding value) used to calculate Zeff of the valence electrons in sulphur (1s 2 2s 2 2p 6 are core (10 total) 3s 2 3p 4 are valence) A) Exactly 10 B) Less than 10 C) More than 10 D) Can t tell without Slater s rules calculations What is the S (shielding value) used to calculate Zeff of the valence electrons in sulphur (1s 2 2s 2 2p 6 are core (10 total) 3s 2 3p 4 are valence) A) Exactly 10 B) Less than 10 C) More than 10 D) Can t tell without Slater s rules calculations 8

Which would you expect to experience a greater effective nuclear charge, a 2p electron of a Ne atom or a 3s electron of a Na atom? A) The 2p electron of a Ne atom.

9 Which would you expect to experience a greater effective nuclear charge, a 2p electron of a Ne atom or a 3s electron of a Na atom? A) The 2p electron of a Ne atom. B) This cannot be determined without knowing the charge of the atom. C) Both the 2s electron and 2p electron experience the same effective nuclear charge. D) The 3s electron of a Na atom. Which would you expect to experience a greater effective nuclear charge, a 2p electron of a Ne atom or a 3s electron of a Na atom? D) The 3s electron of a Na atom. Z increases by one as we move from Ne to Na and S increases by slightly less than one (as shielding is not perfect), therefore Zeff is greater. Zeff=Z-S 9

10 Which of the following is expected to be the correct order of atomic radii from smallest to largest? A) H < C < F B) Mg < Ar < Al C) S < Si < Na D) Ne < B < H Which of the following is expected to be the correct order of atomic radii from smallest to largest? A) H < C < F B) Mg < Ar < Al C) S < Si < Na D) Ne < B < H 10

11 F, Ne, and Na+ are isoelectronic. Which of the following gives the correct ordering of their ionic size (from smallest to largest)? I A) F < Ne < Na+ B) Ne < F < Na+ C) Na+ < Ne < F F, Ne, and Na+ are isoelectronic. Which of the following gives the correct ordering of their ionic size (from smallest to largest)? A) F < Ne < Na+ B) Ne < F < Na+ C) Na+ < Ne < F 11

I 2 (carbon) > is I 1 (carbon) and I 1 (carbon) > I 1 (boron), therefore I 2 for the carbon atom

12 A. I 1 for the boron atom is equal to I 2 for the carbon atom. B. I 2 for the carbon atom is greater. C. I 1 for the boron atom is greater. A. I 1 for the boron atom is equal to I 2 for the carbon atom. B. I 2 for the carbon atom is greater. C. I 1 for the boron atom is greater. I 2 (carbon) > is I 1 (carbon) and I 1 (carbon) > I 1 (boron), therefore I 2 for the carbon atom is greater.. 12

13 Based on periodic trends, which of the following elements is expected to have the largest first ionization energy? A. Li B. Be C. B D. N Based on periodic trends, which of the following elements is expected to have the largest first ionization energy? A. Li B. Be C. B D. N 13

14 Taking into account specific orbitals, which of the following elements is expected to have the largest first ionization energy? A. Li B. Be C. B D. N E. O Taking into account specific orbitals, which of the following elements is expected to have the largest first ionization energy? A. Li B. Be C. B D. N E. O 14

15 Suppose you were asked for a value of the first ionization energy of the Cl - (g) ion. What is the relationship between this quantity and the electron affinity of Cl(g)? Both are endothermic and the EA for Cl is significantly more endothermic than I 1 for Cl. Both are exothermic and the I 1 for Cl is significantly more exothermic than EA for Cl. They are similar in magnitude and opposite in sign. They are similar in magnitude and have the same sign. Suppose you were asked for a value of the first ionization energy of the Cl - (g) ion. What is the relationship between this quantity and the electron affinity of Cl(g)? Both are endothermic and the EA for Cl is significantly more endothermic than I 1 for Cl. Both are exothermic and the I 1 for Cl is significantly more exothermic than EA for Cl. They are similar in magnitude and opposite in sign. They are similar in magnitude and have the same sign. 15

16 Based on periodic trends, which of the following elements is expected to have the largest (i.e., most negative) electron affinity? A. K B. Na C. Si D. S Based on periodic trends, which of the following elements is expected to have the largest (i.e., most negative) electron affinity? A. K B. Na C. Si D. S 16

17 A. the uncertainty principle B. the Pauli exclusion principle C. Hund s rule D. the photoelectric effect Using the periodic table only, which of the following has the lowest Electron affinity? A) N B) Si C) P D) Cl E) O 17

18 Using the periodic table only, which of the following has the lowest Electron affinity? A) N B) Si C) P D) Cl E) O Four atoms and/or ions are sketched below. Which of the following sets of species are compatible with the sketch? A) Br, Li +, Se, I - B) Sr, Cl, Cl -, Na + C) Li +, Br -, Cl -, Mg 2+ 18

19 Four atoms and/or ions are sketched below. Which of the following sets of species are compatible with the sketch? A) Br, Li +, Se, I - B) Sr, Cl, Cl -, Na + C) Li +, Br -, Cl -, Mg 2+ 19

Name: Block: Date: Atomic Radius: the distance from the center of the nucleus to the outer most electrons in an atom.

Name: Block: Date: Atomic Radius: the distance from the center of the nucleus to the outer most electrons in an atom. Name: Block: Date: Chemistry 11 Trends Activity Assignment Atomic Radius: the distance from the center of the nucleus to the outer most electrons in an atom. Ionic Radius: the distance from the center