8.1 Ionic Bonding

Question 1

Ionic bonding :
* The transfer of electrons
* Think about NaCl. Na has 1 electron in its valence shell while Cl has 7 electrons in its. So essentially 1 is transfered to Cl to complete its octet (making Cl-) and 1 is taken from Na to empty its valance shell (making Na+)
* so you have a transfer of electrons form the metal to the nonmetal which gives you a cation and an anion which are attracted to eachother to form that ionic compound
* This is going to be a metal and non metal = ionic bond
* for ionic compounds the difference in electronegativity has to be >1.7 (the bigger the difference the bigger “ionic chacter”)

Covalent bonding
* The sharing of electrons
* 2 non metals = covalent bonding
* Anything less than 1.7 is considered covalent

2 categories of covalent
* Nonpolar covalent <0.5 difference (know C-H is one of these)
* Polar covalent 0.5-1.7 (because once you go passed 1.7 its ionic). We see partial positive, partial negative charges here.
* 2 identical atoms = non polar, they have the same electronegativity

Electronegativivity is the ability of an atom to pull the electrons closer to it when bonded to another atom (so higher electronegativity = it hogs the electrons)

Question 2

Lattice Energy = a measure of the strength of the ionic bond
* The higher the lattice energy the stronger the ionic bond in an ionic compound
* The stronger the ionic bond holding them together, the more endothermic energy (energy done on the system) you will need to break them apart
* So these reactions are highly endothermic

Two big factors that effect the strenght of lattice energy
1) Charge on the ions
2) Size of ions

latice energy is proportional to the charges on the ions divided by the distance between the ions squared
* so higher charges = bigger lattice energy = stronger bond
* smaller distance between ions = bigger lattice energy = stronger bond
* and its the absolute value of this entire formula
* so a +2 cation would lead to a stronger bond than a +1

Also, having smaller distance between the ions leads to stronger bonds. That happens when the atomic radius is smaller

NOTE: the charge typically has a bigger impact on the latice energy than the size of the atom
* so if you are asked to rank which lattice energy is the biggest look at charges first and if charges are all the same then move onto looking at atomic radii

Question 3

Ranking the highest lattice energy
1) LiF
2) NaF
3) MgO
4) MgCl2

Answer 3

You would start by finding the charges on the ions

add the absoulte value of the charges together and thats going to be your highest lattice E compound (or the one w/ the strongest bond)

Question 4

Name the compound w/ the highest latice energy
1) NaF
2) NaCl
3) NaBr
4) NaI

Answer 4

So all the charges are the same, so we can’t really use that

Next, well look at the atomic radii. Remember, the smaller the radii the highest the latice energy (makes sense, if they’re closer together, they’re going to be more attracted to one another, meaning the bond will be stronger)
* so we look at our atomic radii rules and find that NaF has the smallest radii, meaning that it must have the largest lattice energy

Question 5

Answer 5

Question 6

Answer 6

a

Question 7

Answer 7

c

Question 8

Answer 8

start by comparing the charges on all the compounds because thats the most important part and should be looked at before atomic radii

so this is weird, apparently you just compare the charges on the individual atom, even if there are 2 of the,m

Question 9

Answer 9

Question 10

Answer 10

In this one since 2 of them had the same charge you’re now going to need to compare the atomic radii to decide which one has the higher lattice E
* remember, smaller atomic radii = larger lattice energy (because they’re closer together, which means the bond is stronger)

MgO

Question 11

Question 12

Answer 12