91Ó°ÊÓ

The greater the electronegativity difference between two bonded atoms, the greater the percent character of the bond.

Arrange in order of increasing ionic character: \(\mathrm{CsBr}, \mathrm{KBr}, \mathrm{PBr}_{3} \mathrm{MgBr}_{2}\)

Why is HF not considered an ionic compound even though its percent ionic character is greater than \(50 \%\) ?

Give the formula for (a) calcium phosphate, (b)) potassium hydrogen phosphate, (c) magnesium cyanide, (d) barium chlorate.

Hydroxylamine is a compound that contains one nitrogen atom and one oxygen atom connected with a single bond. The remaining atoms are hydrogens. Predict the formula for hydroxylamine and draw its dot diagram.

Give the formula for each compound and indicate whether it is ionic or polar covalent: (a) Copper(I) sulfide (electronegativity of Cu is 1.9) (b) Aluminum carbide (c) Diiodine pentoxide (d) Chlorine trifluoride

Hydrogen sulfide and hydrosulfuric acid have the same molecular formula. How are they different?

It is convenient to classify substances as ionic or covalent. How would you classify sodium sulfate? Explain fully.

\(\mathrm{P}\) is immediately under \(\mathrm{N}\) in the periodic table. Both react with three atoms of chlorine to form \(\mathrm{NCl}_{3}\) and \(\mathrm{PCl}_{3} .\) However, phosphorus also forms \(\mathrm{PCl}_{5}\), whereas nitrogen does not. Draw dot diagrams for all three molecules. In doing so, you will have to violate the octet rule for \(\mathrm{PCl}_{5}\). That is OK. Do it. Then explain why phosphorus can do this but nitrogen can't. (Hint: Nitrogen has only \(2 \mathrm{~s}\) and \(2 p\) orbitals in its valence shell, which together can hold a maximum of eight electrons. Read section \(5.8\) about expanded octet atoms.) Then postulate what kind of atoms might be expected to exceed the octet rule.

Draw a diagram that shows both the covalent and ionic nature of the compound sodium azide, formula \(\mathrm{NaN}_{3}\) (the \(\mathrm{N}_{3}\) portion is linear in shape). If there are resonance forms, then include them.