2.2 electrons, bonding and structure

Question 1

what is ionic bonding

Answer 1

the electrostatic force of attraction between positive and negative ions

Question 2

what are giant ionic lattices?

Answer 2

three dimensional structure of oppositely charged ions, bonded together by strong ionic bonds acting in all directions.
all ioinc compounds are GIANT IONIC LATTICES

Question 3

describe the MP/BP of ionic compounds

Answer 3

high vs most covalent substances
-almost ALL ionic compounds are solid at room temp

Question 4

explain the MP/BP of ionic compounds?

Answer 4

High MP/BP
- high temps are required to provide the large quantities of energy needed to overcome the strong electrostatic forces of attraction between oppositely charged ions

Question 5

suggest a reason for the difference in BP of NaI, NaBr, and NaCl?

Answer 5

chloride ions are smaller than Bromide ions and much smaller than iodide ions, allowing them to be held together closer in their ionic lattice structure, strengthening the forces of attraction between the oppositley charged ions in NaCl vs NaBr and NaI, so more energy is required to overcome the bonds

Question 6

why does KBr have a lower BP than NaBr

Answer 6

-sodium ions are smaller than potassium ions so can pack more closely together in their giant ionic lattice tsructure.
-increases strength EfAs between oppositely charged ions
-more energy to overcome

Question 7

describe and explain the solubility of many ionic compounds?

Answer 7

-dissolve in polar substances [water]
-polar water molecues are attracted to ions on the surface of the lattice
-water molecules bond to the ions, weakening the ionic bonding
-ionic bonds are broken
-ions become surrounded by water molecules and break free from the lattice

Question 8

why may an ionic compound not be considered very soluble?

Answer 8

-in compounds made of ions w large charges
- ionic bonds may be too strong for water molecules to break down the lattice structure
- compound is therfore insoluble in water

Question 9

what must take place in order for an ionic compound to dissolve in water?
what does solubility on an ionic compound depend on?

Answer 9

-Water molecules MUST attract and surround the ions
-ionic lattivce MUST be broken down

-relative strength of attractions within giant ionic lattice
-attraction between ions and water molecules

Question 10

what must take place in order for an ionic compound to dissolve in water?
what does solubility on an ionic compound depend on?

Answer 10

-Water molecules MUST attract and surround the ions
-ionic lattice MUST be broken down

-relative strength of attractions within giant ionic lattice
-attraction between ions and water molecules

Question 11

describe the electrical conductivity of ionic compounds?

Answer 11

-solid state > do not conduct (insulators)
- molten (liquid state) or aqueous (disssolved in water) > electrical conductors

Question 12

explain the electrical conductivity of ionic compounds?

Answer 12

solid
-ions held in fixed position in lattice
-there are no mobile charge carriers
-so cannot conduct electrical energy

molten/aqueous
-solid ionic lattice breaks down
-ions now free to move as mobile charge carriers
-can conduct electrical energy

Question 13

how is electrical conductivity typically effected by concentration?

Answer 13

typically increases, bc more charge-carriers (free-ions) to carry current through the water

Question 14

why would the same conc solution of CaCl2 conduct better than NaCl?

Answer 14

more dissolved ions in the Calcium Chloride solution which are able to carry a charge

Question 15

why would the same conc solution of CaCl2 conduct better than NaCl?

Answer 15

more dissolved ions in the Calcium Chloride solution which are able to carry a charge

Question 16

describe and explain the malleabilty of ionic compounds?

Answer 16

brittle
disruption of the arrangement of (+) and (-) ions is almost guaranteed to end up with repulsions between similarly charged ions that end up next to each other

Question 17

what is a covalent bond?

Answer 17

the strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms

Question 18

which elements form ‘multiple’ covaleent bonds?

Answer 18

oxygen- double
nitrogen- treble

Question 19

*what is a dative covalent bond

Answer 19

covalent bond (EfA between shared pair e-s and nucluei of bonded atoms) in which shared pair electrons are supplied by one of the bonding atoms only
-show as 2 dots/2 crosses

Question 20

example of dative covalent bond formations?

Answer 20

ammonia (NH3) and hydrogen (H+) ion
H+ ion has no electrons
NH3 has 1 lone pair on Nitrogen atom
(draw as two dots/crosses-same as using for N) and (an arrow from N to H to show that they bothe come from N)

Question 21

how many electrons can fill the first 4 shells?

Answer 21

1, 2
2, 8
3, 18
4, 32

Question 22

define the term atomic orbital

Answer 22

region around the nucleus that can hold up to two electrons with opposite spins

Question 23

define the term shell

Answer 23

a number of orbitals with the same principal quantum number(n)

Question 24

define the term electron

Answer 24

cloud of negative charge
-negative charge cloud takes shape of orbital it occupies

Question 25

define the term sub shell

Answer 25

orbitals of the same type in the same shell

Question 26

how many electrons can the 3d orbital hold?

Answer 26

2
ORBITALS CAN HOLD MAX ELECTRONS

Question 27

how many electrons can the s sub shell hold

Answer 27

2

Question 28

how many electrons can a p sub shell hold

Answer 28

(3x2) 6

Question 29

how many electrons can a d sub shell hold?
(5x2) 10

Question 30

how many electrons can the f sub sell hold?

Answer 30

97x2) 14

Question 31

what shape is the s sub shell

Answer 31

sphere
-draw circle

Question 32

what shape is the p sub shell?

Answer 32

dumbell
-draw figure of 8

Question 33

what order do shells fill in?

Answer 33

shells fill in order of increasing energy

Question 34

rules for filling orbitals?

Answer 34

1.orbitals w lowest energy fill first
2. up to 2 electrons per orbitals but MUST have opposite spins
3. If have orbitals w same energy, put electrons into individual orbitals before pairing them (electrons in sam eorbital repel)

Question 35

state the subshells in order of increasing energy up to 4f

Answer 35

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 4d, 4f
4s is LOWER energy> 3d so fills first

Question 36

2 exceptions for electron orbital filling

Answer 36

chromium and copper:
Cr: expected: 3d^4 4s^2 Actual: 3d^5 4s^1
Cu: expected: 3d^9 4s^2 Actual: 3d^10 4s^1

In both cases 4s subshell only contains 1 electron even though there are electrons in the 3d subshell, this is because the 3d subshell is more stable when either half full (Cr) or full (Cu)

Question 37

define electronegativity

Answer 37

ability of an atom to attract the pair of electrons in a covalent bond

Question 38

define non-polar bond

Answer 38

bonded electron pair shared equally between the nuclei of the bonded atoms

Question 39

when do non-polar bonds occur?

Answer 39

small diff in electronegativity
-bonded polar atoms are the same (H2, Cl2)
-bonded atoms have same/similar electronegativities (C and H)

Question 40

what is a pure covalent bond?

Answer 40

non-polar bond, no/negligible diff in electronegaticity, electron pair shared equally between nuclei of bonded atoms

Question 41

what is a polar bond?

Answer 41

bonded pair of electrons is shared unequally between bonded atoms
-each atom will have a small partial +/- charge

form “polar covalent bonds”

Question 42

define the term dipole

Answer 42

the seperation of opposite (partial) charges

Question 43

which shapes are symetrical?

Answer 43

linear
trigonal planar
tetrahedral
octahedral