Which of the group 4A elements have allotropes with the diamond structure? Which have metallic allotropes? How does the variation in the structure of the group 4A elements illustrate how metallic character varies down a periodic group?

In what forms is oxygen commonly found in nature?

Using the shorthand notation of Figure 22.9, draw the structure of the cyclic silicate anion in which four SiO₄ tetrahedra share O atoms to form an eight-membered ring of alternating Si and O atoms. Give the formula and charge of the anion.

GeCl₄ reacts with Cl^- to give GeCl₆^2-, but CCl₄ does not react with excess Cl^-. Explain.

Describe the structures of the white and red allotropes of phosphorus, and explain why white phosphorus is so reactive.

Give an example of an ionic carbide. What is the oxidation state of carbon in this substance?

Compare some of the physical properties of H₂S, NaH, and PdH_x.

Which element in each of the following pairs has more nonmetallic character?

(a) Se or Te

The following pictures represent various silicate anions. Write the formula and charge of each anion.

In the following pictures of binary hydrides, ivory spheres

represent H atoms or ions, and burgundy spheres represent

atoms or ions of the other element.

(1)

(2)

(3)

(4)

(a) Identify each binary hydride as ionic, covalent, or interstitial.

(b) What is the oxidation state of hydrogen in compounds (1), (2), and (3)? What is the oxidation state of the other

element?

The following pictures represent structures of the hydrides of four second-row elements:

(1)

(2)

(3)

(4)

(a) Which compound has the highest melting point?

a. Why is the SO₃ molecule trigonal planar but the SO₃^2– ion is trigonal pyramidal?

Which compound in each of the following pairs is more covalent?

(a) PCl₃ or AlF₃

An important physiological reaction of nitric oxide (NO) is its interaction with the superoxide ion (O₂^–) to form the peroxynitrite ion (ONOO^–).

a. Write electron-dot structures for NO, O₂^–, and ONOO^–, and predict the O–N–O bond angle in ONOO^–.

Write a balanced net ionic equation for the reaction of the amphoteric oxide Ga₂O₃ with:

a. Aqueous sulfuric acid

Write a balanced net ionic equation for the reaction of the amphoteric oxide ZnO with:

a. Hydrochloric acid

Consider the six second- and third-row elements in groups 4A–6A of the periodic table:

Possible structures for the binary fluorides of each of these elements in its highest oxidation state are shown below.

(a) Identify the nonfluorine atom in each case, and write the molecular formula of each fluoride.

Which compound in each of the following pairs is more ionic?

(b) P4O6 or Ga2O3

Select the group 4A element that best fits each of the following descriptions.

b. Is the least dense semimetal

In the following pictures of binary hydrides, ivory spheres

represent H atoms or ions, and burgundy spheres represent

atoms or ions of the other element.

(1)

(2)

(3)

(4)

(b) What is the oxidation state of hydrogen in compounds (1), (2), and (3)? What is the oxidation state of the other

element?

Consider the six second- and third-row elements in groups 4A–6A of the periodic table:

Possible structures for the binary fluorides of each of these elements in its highest oxidation state are shown below.

(b) Explain why the fluorides of nitrogen and phosphorus have different molecular structures but the fluorides of carbon and silicon have the same molecular structure.

Look at the location of elements A, B, C, and D in the following periodic table:

(b) Classify each oxide as basic, acidic, or amphoteric.

The following pictures represent structures of the hydrides of four second-row elements:

(1)

(2)

(3)

(4)

(b) Which compound has the lowest boiling point?

The following models represent the structures of binary hydrides of second-row elements:

b. Draw an electron-dot structure for each hydride. For which hydride is there a problem in drawing the structure? Explain.

Look at the location of elements A, B, C, and D in the following periodic table:

Which hydride has the lowest boiling point?

Complete and balance the equation for each of the following reactions.

b. Ca(s) + H₂O(l) →

Consider the elements N, Si, Al, S, and F. Identify which of these elements:

c. Is a semiconductor

Identify the group 3A element that best fits each of the following descriptions.

(c) Is extremely toxic

Consider the elements C, Se, B, Sn, and Cl. Identify which of these elements:

c. Is the best electrical conductor

Complete and balance the equation for each of the following reactions.

d. $C_2H_6\left(g\right)+H_2O\left(g\right)\overset{heat}{\underset{catalyst}\rightarrow}$