quiz #3

Question 1

elements in groups exhibit…

Answer 1

similar chemical behaviour

Question 2

why doe elements in groups exhibit similar chemical behavior?

Answer 2

members of a group have the same number and distribution of valence electrons

Question 3

the physical and chemical behavior of elements is ultimately based on what?

Answer 3

the electron configuration of their atoms

Question 4

definition of atomic radii

Answer 4

distance between electrons and nuclei

Question 5

definition of metallic radii (used for metals)

Answer 5

1/2 the distance between 2 atoms in a crystal of the element

Question 6

atomic size

Answer 6

1/2 the distance between nuclei of identical covalently bonded atoms

Question 7

explain changes in the principle quantum number (n)

Answer 7

atoms become larger as “n” increases - the probability that the outer electrons will spend more time farther from the nucleus increases

Question 8

explain changes in Zeff

Answer 8

atoms become smaller as Zeff increases - as effective nuclear charge increases, outer electrons are pulled closer to the nucleus

Question 9

what is Zeff

Answer 9

effective nuclear charge, it is how much an electron feels the pull of protons in the nucleus (therefore, more protons = more pull)

Question 10

explain how n increases on the periodic table

Answer 10

n increases down a group (more electrons = larger orbitals), so atoms become larger

Question 11

explain how Zeff increases on the periodic table

Answer 11

Zeff dominates across a period as protons increase, and electrons feel a greater pull from the nucleus (atoms become smaller)

Question 12

what causes changes in atomic size?

Answer 12

changes in principle quantum number, changes in Zeff

Question 13

atomic size in transition elements

Answer 13

shielding by inner d-electrons counteracts the increase in Zeff, so size remains relatively constant across a period

Question 14

ionic size vs atomic size - cations

Answer 14

cations are smaller tha their parent ions: electron repulsion decreases, Zeff increases

Question 15

ionic size vs atomic size - anions

Answer 15

anions are larger than their parent atoms: electron repulsion increases so they take up more space

Question 16

define ionization energy

Answer 16

the energy in kJ require for the complete removal of 1 mol of electrons from 1 mol of gaseous atoms/ions

Question 17

simplify ionization energy

Answer 17

taking an electron away, making the atom POSITIVE

Question 18

general trend for ionization energy:

Answer 18

as size decreases, it takes more energy to remove an electron = higher ionization energy

Question 19

what are the exceptions/anomalies for ionization energy?

Answer 19

B has lower IE than Be; O has lower IE than N

Question 20

why doesn’t IE decrease between Al and Ga?

Answer 20

due to the increased Zeff in Ga; 4p orbitals penetrate more than 3d so the electrons in Ga feel a much larger Zeff than in Al

Question 21

define electron affinity

Answer 21

energy change in kJ accompanying the addition of 1 mol of electrons to 1 mol of gaseous atoms/ions

Question 22

what is the EA trend for reactive metals?

Answer 22

group 1A and 2A have low IE and slightly positive EA - they form positive ions

Question 23

what is the EA trend for reactive nonmetals?

Answer 23

group 6A and 7A form negative ions

Question 24

explain EA on the periodic table

Answer 24

it decreases down a group (with many exceptions) and increases along a period

Question 25

define ionic bonding

Answer 25

transfer of electrons from metal to nonmetal to form ions that come together in a solid ionic compound

Question 26

define lattice energy

Answer 26

the energy associated with forming crystalline lattice of alternating anions and cations from the gaseous ion - exothermic process

Question 27

what does lattice energy indicate?

Answer 27

strength of ionic interactions, influences melting point, solubility & other properties

Question 28

why do ionic solids exist?

Answer 28

the lattice energy exceeds the energetically unfavorable electron transfer

Question 29

how are lattice energies calculated?

Answer 29

using the Born-Haber cycle, which is a series of chosen hypothetical steps with known enthalpies

Question 30

ionic solids, ie:

Answer 30

energy require for elements to lose/gain electrons is supplied by the attraction between the ions they form

Question 31

what does lattice energy depend on?

Answer 31

depends on ionic size, ionic charge and ionic arrangement in a solid

Question 32

what is coulomb’s law?

Answer 32

lattice energy is proportional to charge over radius

Question 33

what happens to lattice energy when ionic size increases?

Answer 33

lattice energy decreases

Question 34

what is the formula for electrostatic force?

Answer 34

electrostatic force is proportional to charge/distance^2

Question 35

what is the formula for energy?

Answer 35

force x distance