Chapter 8

Question 1

what is periodic property?

Answer 1

a property of an element that is predictable based on the elements position in the periodic table

Question 2

what are valence electrons?

Answer 2

the electrons important in chemical bonding. for main group elements, these electrons are found in the outermost principal energy level

Question 3

what are core electrons?

Answer 3

electrons in complete principal energy levels, and complete d and f sublevels not including the valence electrons

Question 4

orbital blocks in the periodic table?

Answer 4

you can see that the number of columns in a block correspond to the maximum number of electrons that can occupy the particular sublevel of the block

Question 5

principal level and rows in the periodic table?

Answer 5

the row number in the periodic table is equal to the number (or n value) of the highest principal level
ie) since Cl is in the 3rd row its highest principal level is n=3

Question 6

Summarizing the periodic table organization?

Answer 6

1. The periodic table is divisible into four blocks corresponding to the filling of the four quantum sublevels (s,p,d,f)
2. The row number of a main-group element is equal to the highest principal quantum number of that element

Question 7

How do we fill the f-block?

Answer 7

for the principal quantum number of the f orbitals being filled across each row in the inner transition series is the row number minus TWO

Question 8

what is a non-bonding atomic radius (Van der Waals radius) ?

Answer 8

a way to determine and atomic radius of an element: The radius of an atom determined from the distance between atomic centres in an atomic solid

Question 9

what is the Van der Waals radius?

Answer 9

is one-half the distance between adjacent nuclei in the atomic solid

Question 10

what is a bonding atomic radius (covalent radius) ?

Answer 10

For non-metals: one-half the distance between the two atoms bonded together
For metals: one-half the distance between two of the atoms next to each other in a crystal of the metal

Question 11

what is an atomic radius?

Answer 11

average bonding radius for a given element, determined from large numbers of compounds

Question 12

what are the general trends in the atomic radii of main group elements?

Answer 12

1. the principal quantum number ( n) of the electrons in the outermost principal energy level increases, resulting in larger orbitals and therefore larger atomic radii.
2. the effective nuclear charge experienced by the electrons in the outermost principal energy level in-creases, resulting in a stronger attraction between the outermost electrons and the nucleus, and smaller atomic radii.

Question 13

what is the effective nuclear charge?

Answer 13

The effective nuclear charge experienced by a particular electron in an atom is the actual nuclear charge (Z) minus the charge shielded by other electrons (S)

Zeff = Z - S

Question 14

what do core electrons do?

Answer 14

Core electrons efficiently shield electrons in the outermost principal energy level from nuclear charge, but outermost electrons do not efficiently shield one another from nuclear charge.

Question 15

what are Slater’s rules?

Answer 15

empirical rules for estimating the shielding constant and the effective nuclear charge experienced by each valence electron

S = N(n)f(n) + N(n-1)f(n-1) + N(

Question 16

what is lanthanoid contraction?

Answer 16

the trend toward leveling off in size of the atoms in the third and fourth transition rows due to the ineffective shielding of the f sublevel electrons

Question 17

sizes of atoms and their cations?

Answer 17

cations are much smaller than their corresponding atoms

Question 18

sizes of atoms and their anions?

Answer 18

anions are much larger than their corresponding atoms

Question 19

what is ionization energy?

Answer 19

The energy required to remove an electron from an atom or ion in its gaseous state

Question 20

summarizing ionization energy for main-group elements?

Answer 20

1. Ionization energy GENERALLY DECREASES as we move down a column in the periodic table because electrons in the outermost principal level are increasingly farther away from the positively charged nucleus and are therefore held less tightly
2. ionization energy GENERALLY INCREASES as we move to the right across a row in the periodic table because electrons in the outermost principal energy level generally experience a greater effective nuclear charge (Zeff)

Question 21

what is electron affinity?

Answer 21

the energy required to remove an electron from a negative ion in the gas phase: The energy change associated with the gaining of an electron by an atom in the gaseous state

Question 22

Summarizing electron affinity for main group elements

Answer 22

1. most groups of the periodic table do not exhibit any definite trend in electron affinity: however among the group 1 elements the electron affinity decreases as we move down the column
2. electron affinity GENERALLY INCREASES as we move to the right across the row in a periodic table

Question 23

what are the trends in metallic character?

Answer 23

1. as we move down a column in the periodic table, metallic character INCREASES
2. as we move to the right, across a row in the periodic table, metallic character DECREASES