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Match the molecule with the kind of bond which is made. (All answers must be correct for credit.)
FI = 4.0 - 2.6 = 1.4 (polar covalent)
CsI = 0.7 - 2.7 = 2.0 (ionic)
H2 = 2.1 - 2.1 = 0 (pure covalent
What is the difference in electronegativity for the most ionic of the following compounds: CsCl, MgF2, FI, and NH3?
CsCl: 0.7 - 3.0 = 2.3
MgF2 : 1.2 - 4.0 = 2.8
FI : 4.0 - 2.5 = 1.5
NH3 : 0.9 - 2.1 = 1.2
What is the difference in electronegativity between the atoms in HI?
HI : 2.1 - 2.5 = 0.4
I is more electronegative than H, which means that I is polarized with negative charge. Therefore, H has to be positively charged. If H is positive than it attracted to the negative plate.
Which of the following ionic compounds has the highest melting point?
The molecule with the smallest radius of elements (means they share have a strong bond) and highest total charge is the ionic compound with the highest melting point.
Be O : (+2) ( - 2) = -4
radius: Be has smaller radius than Sr
This formula is used to determine the strength of the bond. The stronger the force the higher the melting point.
The molecule with the biggest radius of elements (means they share have a weaker bond) and smallest total charge is the ionic compound with the lowest melting point.
This formula is used to determine the strength of the bond. The weaker the force the lower the melting point.
[Ar] 3d10 4s2 4p5
How to create Lewis Structure
Which of the following statements about Lewis Structures is FALSE?
Carbon can make only 4 bonds.
Write the Lewis structure for H2O and check those statements which are correct.
Write the Lewis structure for NH41+ and check those statements which are correct.
Which bonding structure (lone pairs of electrons not shown) correctly represents hydroxylamine, NH3O? Also, check those statements which are correct for the completed Lewis structure.
Left Structure: oxygen has -1 charge making overall charge -1
Right Structure: all element have 0 charge making overall charge 0 corresponds to the overall charge of the formula NH3O. (best choice)
Which bonding structure (lone pairs of electrons not shown) correctly represents phosphorous acid, H3PO3? Also, check those statements which are correct for the completed Lewis structure satisfying the octet rule.
Formaldehyde, H2CO, is a gas with a characteristic pungent odor. Draw its Lewis structure. Which statements are correct regarding its Lewis structure?
Draw the Lewis structures for the carbonate ion, CO32-. Which statements are correct regarding its Lewis structures?
Steric Number: number of lone pairs + number of bonds (single, double, triple bonds are counted as one)
Nitrogen Steric Number
1 lone pair + 1 bond = 2
Draw the Lewis structure for the PCl5. Which statements are correct regarding its Lewis structure?
P Cl : 5 + (5 x 7) = 40 valence electrons
P : 5 bonds + 0 lone pairs = 5
octet rule is not obeyed because more than 8 electrons are shared by P
I3- : ( 3 x 7 ) + 1 = 22
IO2F2- : 7 + (6 x 2) + (7 x 2) + 1 = 34 valence electrons
I = 5 bonds + 0 lone pair = 5 steric number
Arrange the following diatomic molecules in order of weakest to strongest bond: HF, HCl, HBr, and HI. Write your answer with or without commas and do not include the "and". For example, alphabetically, you would write: HBr, HCl, HF, HI or HBr HCl HF HI.
Aside, do you notice a pattern?
H - Br : 368 kJ/mol
HCl: 431 kJ/mol
HF: 569 kJ/mol
HI: 297 kJ/mol
lowest to highest
HI HBr HCl HF
O2 : 498 kJ/mol
O-O: 146 kJ/ mol
498 kJ/mol - 146 kJ/mol = 352kJ/ mol
What energy in kJ is required to break 3.31 mol of NH3 into atoms? As noted below, this information can be used to calculate ΔH for gas-phase reactions.
3 x N-H =1167 kJ/ mol
3.31 mol x 1167 kJ/ mol = 3862.77 kJ
What is the approximate ΔH in kJ for the following reaction as written:
2NH3(g) --> 3H2(g) + N2(g)
Careful, what kind of bond does the nitrogen molecule make?
ΔH = H(products) - H(reactants)
ΔH = [(3*436) + 946] - 2*[3*389]
ΔH = -80 J/mol
It should be positive because it is endothermic reaction and bonds are being broken to single elements.
so... ΔH = 80 J/mol
Nitrogen makes a triple bond with itself, therefore, use that value (N≡N ~ 946 kJ/mol)