Practice problems Electron Configuration And Periodic Properties Practice

Practice problems Electron Configuration And Periodic Properties

Practice Problem #1 • Of the elements Li, O, C, and F, identify the one with the largest atomic radius and the one with the smallest radius. • Atomic radius decreases across a period due to increasing nuclear charge. • Li has the largest atomic radius – it is a group 1 element (i. e. , furthest to the left in the period • F has the smallest atomic radius – it is furthest to the right in the period, has the highest nuclear charge.

Practice Problem #2 • Of the elements Br, At, F, I and Cl, identify the one with the largest atomic radius and the one with the smallest radius. • Atomic radius increases down a group due to the outer electrons filling orbitals in higher main energy levels further from the nucleus. • F has smallest atomic radius (at the top of the group) • At has largest atomic radius (at the bottom of the group)

Practice Problem #3 • What is ionization energy? • Ionization energy is the energy required to remove one electron from a neutral atom of an element. • A + energy A+ + e-

Practice Problem #4 • What is an ion? What is ionization? • An ion is a charged atom or a group of atoms with a charge. The charge can be positive or negative. • Ionization is any process that results in the formation of an ion.

Practice Problem #5 • What are second, third, etc. ionization energies? • The removal of an electron from a neutral atom is the first ionization energy. The removal of additional electrons from a positive ion is the second ionization energy, third ionization energy, etc. • The ionization energy increases for each successive ionization because the electron feels an increasingly stronger nuclear charge.

Practice Problem #6 a • • • Q: 3 s 23 p 5 R: 3 s 1 T: 5 s 24 d 105 p 5 X: 5 s 24 d 105 p 1 What is the block and location of each? Q: p block, group 17; period 3 R: s block, group 1, period 3 T: p block, group 17, period 5 X: p block, group 13, period 5

Practice Problem #6 b • • • Q: 3 s 23 p 5 R: 3 s 1 T: 5 s 24 d 105 p 5 X: 5 s 24 d 105 p 1 Which elements are in the same period? Q & R in same period; T&X in same period Which elements are in the same group? Q&T in same group

Practice Problem #6 c • Q: 3 s 23 p 5 R: 3 s 1 T: 5 s 24 d 105 p 5 X: 5 s 24 d 105 p 1 • Which one has the highest first ionization energy? • Highest first ionization energy: Q (furthest to the top right of periodic table) • Which one has the lowest first ionization energy? • Lowest first ionization energy: R (alkali metal, have low ionization energies.

Practice Problem #6 d • Q: 3 s 23 p 5 R: 3 s 1 T: 5 s 24 d 105 p 5 X: 5 s 24 d 105 p 1 • Which would you expect to have the highest second ionization energy? • After the first ionization, R attains an electron configuration like a noble gas. It would take a lot of energy to remove a second electron. The other elements still have electrons in their outmost energy level, so it would not take as much energy to remove a second electron from those elements.

Practice Problem #7 • Define valence electrons: • Valence electrons are the electrons that are available to be lost, gained, or shared in the formation of a chemical compound.

Practice Problem #8 • In which shells are the valence electrons found and why are they important? • Valence electrons are found in the highest occupied energy level. These are the electrons that are involved in chemical bonding.

Practice Problem #9 • Among the main group elements, what is the relationship between the group number and the number of valence electrons among group members? • Group 1: ns 1 1 valence electron (same as group #) • Group 2: ns 2 2 v. e. (same as group #) • Group 13: ns 2 np 1 3 v. e. (group # -10) • Group 14: ns 2 np 2 4 v. e. (group # - 10) • Etc.

Practice Problem #9 • In general, how do the periodic properties of the dblock elements compare with those of the main group elements? • Atomic radii – decreases across period but the decrease is less than in main group • Ionization energies – different from main group elements in that energies increase going down a group because valence electrons in s sublevel are less shielded • Electronegativity – have the lowest electronegativity values, aside from Groups 1 and 2; but do tend to follow trend that electronegativity increases as radii decrease.