Determine the total number of valence electrons for each of the following: a. $\mathrm{SBr}_2$ b. $\mathrm{NBr}_3$ c. $\mathrm{CH}_3 \mathrm{OH}$ d. $\mathrm{NH}_4{ }^{+}$

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

Compare the electron-dot formulas of $\text{BF}_{3}$ and $\text{NF}_{3}$. Why do these molecules have different shapes?

In a molecule of H_{2}, the four electron groups around the sulfur atom are arranged in a tetrahedral geometry. However, the shape of the molecule is called bent. Why does the shape of the molecule have a different name from the name of the electron group geometry?

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

In the molecule $\text{PCl}_{3}$, the four electron groups around the phosphorus atom are arranged in a tetrahedral geometry. However, the shape of the molecule is called trigonal pyramidal. Why does the shape of the molecule have a different name from the name of the electron group geometry?

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

Predict the shape of a molecule with each of the following:

a. Four bonded atoms

b. Two bonded atoms and two lone pairs

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

Predict the shape of a molecule with each of the following:

a. Two bonded atoms and no lone pairs

b. Three bonded atoms and one lone pair

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 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 $0^{\circ} \mathrm{C} ?(10.5)$

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)