Chapter 8

Question 1

actinides

Answer 1

the Period 7 elements that constitute the second inner transition series (5f block), which includes thorium (Th; Z = 90) through lawrencium (Lr; Z = 103)

Question 2

amphoteric

Answer 2

able to act as either an acid or a base

Question 3

atomic size

Answer 3

a measure of how closely one atom lies next to another, determined from the distances between nuclei of adjacent atoms

Question 4

aufbau principle

Answer 4

the conceptual approach for building up atoms by adding one proton at a time to the nucleus and one electron to the lowest energy sublevel that is available, to obtain the ground-state electron configurations of the elements

Question 5

covalent radius

Answer 5

one-half the shortest distance between nuclei of identical covalently bonded atoms

Question 6

dimagnetism

Answer 6

the tendency of a species not to be attracted (or to be slightly repelled) by a magnetic field as a result of its electrons being paired

Question 7

effective nuclear charge (Zeff)

Answer 7

the nuclear charge an electron actually experiences as a result of shielding effects due to the presence of other electrons

Question 8

electron affinity (EA)

Answer 8

the energy change (in kJ) accompanying the addition of 1 mol of electrons to 1 mol of gaseous atoms or ions.

Question 9

electron configuration

Answer 9

the distribution of electrons within the levels and sublevels of the atoms of an element; also the notation for such a distribution

Question 10

Hund’s rule

Answer 10

a principle stating that, when orbitals of equal energy are available, the electron configuration of lowest energy has the maximum number of unpaired electrons with parallel spins

Question 11

inner (core) electrons

Answer 11

electrons that fill all the energy levels of an atom except the valence level; electrons also present in atoms of the previous noble gas and any completed transition series

Question 12

inner transition elements

Answer 12

the elements of the periodic table in which the seven inner f orbitals are being filled; the lanthanides and the actinides

Question 13

ionic radius

Answer 13

the size of an ion as measured by the distance between the nuclei of adjacent ions in a crystalline ionic compound

Question 14

ionization energy (IE)

Answer 14

the energy (in kJ) required for complete removal of 1 mol of electrons from 1 mol of gaseous atoms or ions

Question 15

isoelectronic

Answer 15

having the same number and configuration of electrons as another species

Question 16

lanthanides

Answer 16

the Period 6 (4f) series of inner transition elements, which includes cerium (Ce; Z = 58) through lutetium (Lu; Z = 71)

Question 17

metallic radius

Answer 17

one-half the shortest distance between the nuclei of adjacent individual atoms in a crystal of an element

Question 18

orbital diagram

Answer 18

a depiction of orbital occupancy in terms of electron number and spin shown by means of arrows in a series of small boxes or on a series of short lines

Question 19

outer electrons

Answer 19

electrons that occupy the highest energy level (highest n value) and are, on average, farthest from the nucleus

Question 20

paramagnetism

Answer 20

the tendency of a species with unpaired electrons to be attracted by an external magnetic field

Question 21

pauli exclusion principle

Answer 21

a principle developed by Wolfgang Pauli stating that no two electrons in an atom can have the same set of four quantum numbers. the principle arises from the fact that an orbital has a maximum occupancy of two electrons and their spins are paired

Question 22

penetration

Answer 22

the phenomenon in which an outer electron moves through the region occupied by the core electrons to spend part of its time closer to the nucleus; penetration increases the average effective nuclear charge for that electron

Question 23

periodic law

Answer 23

a law stating that, when the elements are arranged by atomic mass, they exhibit a periodic recurrence of properties

Question 24

pseudo-noble gas configuration

Answer 24

the (n − 1)d10 configuration of a p-block metal ion that has an empty outer energy level

Question 25

shielding

Answer 25

the ability of other electrons, especially those occupying inner orbitals, to lessen the nuclear attraction for an outer electron

Question 26

spin quantum number

Answer 26

a number, either +1/2 or -1/2 that indicates the direction of electron spin

Question 27

transition elements

Answer 27

an element that occupies the d block or the f block (inner transition element) of the periodic table