Use VSEPR theory to predict the shape of each of the following: a. $\mathrm{GaH}_3$ b. $\mathrm{OF}_2$ c. $\mathrm{HCN}$ d. $\mathrm{CCl}_4$

Using only a periodic table as a guide, arrange the following atoms in order of decreasing electronegativity: $\mathrm{In} \quad \mathrm{Se} \quad \mathrm{Sb} \quad \mathrm{Cl} \quad \mathrm{S}$

What is the formula for nickel(III) oxide?

Compare the electron-dot formulas of $\mathrm{CH}_4$ and $\mathrm{H}_2 \mathrm{O}$. Why do these molecules have similar bond angles but different names for their shapes?

Compare the electron-dot formulas of $\mathrm{CF}_4$ and $\mathrm{NF}_3$. Why do these molecules have different shapes?

Choose the shape (1-6) that matches each of the following descriptions (a-c):

1. linear
2. bent $\left(109^{\circ}\right)$
3. trigonal planar
4. bent $\left(120^{\circ}\right)$ 5. trigonal pyramidal
5. tetrahedral a. a molecule with a central atom that has four electron groups and two bonded atoms b. a molecule with a central atom that has two electron groups and two bonded atoms c. a molecule with a central atom that has three electron groups and two bonded atoms

Choose the shape (1-6) that matches each of the following descriptions (a-c):

1. linear $\quad$ 2. bent $\left(109^{\circ}\right) \quad$ 3. trigonal planar
2. bent $\left(120^{\circ}\right)$ 5. trigonal pyramidal
3. tetrahedral a. a molecule with a central atom that has four electron groups and four bonded atoms b. a molecule with a central atom that has four electron groups and three bonded atoms c. a molecule with a central atom that has three electron groups and three bonded atoms

Draw resonance structures for each of the following molecules or ions: a. $\mathrm{HCO}_2^{-}(\mathrm{C}$ is the central atom $)$ b. $\mathrm{N}_2 \mathrm{O}$

A 3.0-kg block of lead is taken from a furnace at $300^{\circ} \mathrm{C}$ and placed on a large block of ice at $0{ }^{\circ} \mathrm{C}$. The specific heat of lead is $0.13 \mathrm{~J} / \mathrm{g}{ }^{\circ} \mathrm{C}$. If all the heat given up by the lead is used to melt ice, how much ice is melted when the temperature of the lead drops to $0{ }^{\circ} \mathrm{C}$ ? $(10.5)$

Draw resonance structures for each of the following molecules or ions: a. $\mathrm{ClNO}_2$ ( $\mathrm{N}$ is the central atom) b. $\mathrm{OCN}^{-}(\mathrm{C}$ is the central atom)

An ice cube at $0^{\circ} \mathrm{C}$ with a mass of $115 \mathrm{~g}$ is added to $\mathrm{H}_2 \mathrm{O}$ in a beaker that has a temperature of $64.0^{\circ} \mathrm{C}$. If the final temperature of the mixture is $24.0^{\circ} \mathrm{C}$, what was the initial mass of the warm water? (10.5)

An ice cube tray holds $325 \mathrm{~g}$ of water. If the water initially has a temperature of $25^{\circ} \mathrm{C}$, how many kilojoules of heat must be removed to cool and freeze the water at $0^{\circ} \mathrm{C} ?(10.5)$

Draw the electron-dot formula for each of the following molecules or ions: a. $\mathrm{HCCH}$ (ethyne) b. $\mathrm{CS}_2$ c. $\mathrm{NO}^{+}$

How many kilojoules are released when $75.0 \mathrm{~g}$ of steam at $100{ }^{\circ} \mathrm{C}$ condenses, cools to $0^{\circ} \mathrm{C}$, and freezes? (Hint: The solution will require three energy calculations.)