# 2.E: Atoms, Molecules, and Ions

1. Which law is supported by each of the following statements? (The laws are: conservation of mass, definite proportion, and multiple proportions.)

1. In hydrogen peroxide there are 15.9 grams of oxygen per 1.00 g of hydrogen and in water there are 7.94 grams of oxygen per 1.00 g of hydrogen.
2. The total mass of reactants (starting materials) is the same as the total mass of products when a chemical reaction is carried out in a closed system.
3. In any sample of a given compound, the mass proportion of each element is the same.

1. What are two conclusions supported by Rutherford’s experiment?

1. Fill in the following table:
 Nuclear Symbol Atomic Number Mass Number Number of Protons Number of Electrons Number of Neutrons Charge $$\mathrm{^{40}_{18}Ar}$$ 39 19 18 16 20 -2
1. Write the nuclear symbols for the isotopes of neon which contain 10 neutrons and 12 neutrons.

1. For each of the following elements, indicate whether it is a main group element (MG), transition metal (TM), or inner transition metal (ITM).  If the element is a main group element, indicate the group number and whether it is a metal, a nonmetal or a metalloid.  Also indicate the Period of each element.
1. $$\ce{Sr}$$ (atomic # 38)
2. $$\ce{Br}$$ (atomic # 35)
3. $$\ce{Mo}$$ (atomic # 42)
4. $$\ce{P}$$ (atomic # 15)
5. $$\ce{B}$$ (atomic # 5)
6. $$\ce{U}$$ (atomic # 92)
7. $$\ce{Sn}$$ (atomic # 50)
8. $$\ce{Hg}$$ (atomic # 80)

1. Provide the common names of Groups 1, 2, 17 and 18.

1. Give an example of at least one element made up of molecules and one compound made up of molecules.

1. For each of the following atoms, indicate whether it forms a positive or a negative ion, and include the ion charge.
1. $$\ce{Na}$$
2. $$\ce{Ba}$$
3. $$\ce{Cl}$$
4. $$\ce{S}$$
5. $$\ce{Ag}$$

1. Which of the following are ionic compounds?  Which are covalent compounds?  Name each compound.
1. $$\ce{N2O}$$
2. $$\ce{K2O}$$
3. $$\ce{PCl3}$$
4. $$\ce{AlPO4}$$
5. $$\ce{HCl}$$
6. $$\ce{NH4F}$$
7. $$\ce{Pb(NO2)2}$$
8. $$\ce{H2SO3}$$

1. Name the following ionic compounds:
1. $$\ce{CaCO3}$$
2. $$\ce{ZnS}$$
3. $$\ce{CuOH}$$
4. $$\ce{Mg(ClO4)2}$$

1. Give the formulas for the following ionic compounds:
1. potassium phosphate
2. ammonium sulfate
3. cobalt(II) hydroxide
4. iron(III)nitride

1. Provide the formulas for the following covalent compounds:
1. phosphorus triiodide
2. dinitrogen pentoxide
3. chloric acid