Chapter 2

Give the names and symbols of three elements.

Describe where protons, neutrons, and electrons are located in an atom.

How many protons are in the nucleus of each of the following atoms? a. neon (Ne) b. gold (Au) c. strontium (Sr) d. uranium (U)

A certain atom contains 28 protons, 28 electrons, and 31 neutrons. Provide the following: a. atomic number b. mass number c. name of element

How many protons, neutrons, and electrons are in an atom of cesium-133?

How many protons, neutrons, and electrons are there in the atom \({ }_{9}^{19} \mathrm{~F}\) ?

How many protons, neutrons, and electrons are there in an atom of lead-207?

A certain atom has an atomic number of 36 and a mass number of 84 . Write out the designation for this isotope in both nuclide symbol form and in hyphenated form.

An atom has a mass number of 59 and contains 32 neutrons in its nucleus. What element is it?

Which one is an isotope of \({ }_{18}^{40} \mathrm{Ar}\) ? Explain. a. \({ }_{20}^{40} \mathrm{Ca}\) b. \({ }_{18}^{39} \mathrm{Ar}\) c. \({ }_{18}^{40} \mathrm{Ar}\)

Define matter and give three examples of matter.

Explain the differences between compounds and mixtures.

Explain the differences between pure substances and mixtures.

Identify each of the following as a pure substance or a mixture. a. salt water b. \(\mathrm{NaCl}\) c. brewed coffee d. air

Label each of the following as an element, compound, homogeneous mixture, or heterogeneous mixture. a. silicon b. sulfuric acid c. air d. soda e. sugar f. muddy water g. chicken noodle soup h. scoop of sand from the beach

Identify each of the following elements as a metal, nonmetal, or metalloid. a. iron (Fe) b. gallium (Ga) c. phosphorus (P) d. potassium (K) e. neon (Ne) f. germanium (Ge)

Identify each of the following elements as a metal, nonmetal, or metalloid. a. chlorine (Cl) b. hydrogen (H) c. antimony (Sb) d. titanium (Ti) e. nitrogen (N) f. selenium (Se)

Describe how you identify molecular and ionic compounds.

Label each as an ionic or molecular compound. a. \(\mathrm{H}_{2} \mathrm{O}_{2}\) b. \(\mathrm{N}_{2} \mathrm{O}_{5}\) c. \(\mathrm{PF}_{3}\) d. \(\mathrm{MgCl}_{2}\) e. \(\mathrm{KBr}\) f. \(\mathrm{AlCl}_{3}\)

Label each as an ionic or molecular compound. a. \(\mathrm{CaO}\) b. \(\mathrm{Na}_{2} \mathrm{~S}\) c. \(\mathrm{NH}_{3}\) d. \(\mathrm{CO}_{2}\) e. \(\mathrm{N}_{2} \mathrm{H}_{4}\) f. \(\mathrm{N}_{2} \mathrm{O}\)

Define "counting number".

What seven elements exist as diatomic molecules in nature?

How many atoms of helium are present in each of the following samples? a. 1 mole b. 2 moles c. \(2.5\) moles d. \(0.5\) moles e. \(0.35\) moles

How many molecules of water are present in each of the following samples? a. 1 mole b. 2 moles c. \(2.5\) moles d. \(0.5\) moles e. \(0.35\) moles

How many moles of silicon is \(6.73 \times 10^{25}\) atoms of silicon?

How many moles of sodium is \(4.29 \times 10^{22}\) atoms of sodium?

How many atoms of each element are in one unit of each compound? a. \(\mathrm{H}_{2} \mathrm{O}_{2}\) b. \(\mathrm{N}_{2} \mathrm{O}_{5}\) c. \(\mathrm{PF}_{3}\) d. \(\mathrm{MgCl}_{2}\) e. \(\mathrm{KBr}\) f. \(\mathrm{AlCl}_{3}\) g. \(\mathrm{CaO}\) h. \(\mathrm{Na}_{2} \mathrm{~S}\) i. \(\mathrm{NH}_{3}\) j. \(\mathrm{CO}_{2}\) k. \(\mathrm{N}_{2} \mathrm{H}_{4}\) l. \(\mathrm{N}_{2} \mathrm{O}\)

How many moles of each element are in one mole of each compound? a. \(\mathrm{H}_{2} \mathrm{O}_{2}\) b. \(\mathrm{N}_{2} \mathrm{O}_{5}\) ?. \(\mathrm{PF}_{3}\) d. \(\mathrm{MgCl}_{2}\) e. \(\mathrm{KBr}\) f. \(\mathrm{AlCl}_{3}\) g. \(\mathrm{CaO}\) h. \(\mathrm{Na}_{2} \mathrm{~S}\) i. \(\mathrm{NH}_{3}\) j. \(\mathrm{CO}_{2}\) k. \(\mathrm{N}_{2} \mathrm{H}_{4}\) l. \(\mathrm{N}_{2} \mathrm{O}\)

How many moles of carbon are in \(0.75\) moles of \(\mathrm{CCl}_{4}\) ? How many moles of chlorine?

How many atoms of carbon are in \(0.75\) moles of \(\mathrm{CCl}_{4}\) ? How many atoms of chlorine?

How many moles of hydrogen are in \(2.5\) moles of \(\mathrm{H}_{2} \mathrm{O}\) ? How many moles of oxygen?

How many atoms of hydrogen are in \(2.5\) moles of \(\mathrm{H}_{2} \mathrm{O}\) ? How many atoms of oxygen?

A sample of propane gas \(\left(\mathrm{C}_{3} \mathrm{H}_{8}\right)\) contains \(5.39 \times 10^{24}\) atoms of carbon. How many atoms of hydrogen are in the sample?

What is the molar mass of each of the following elements (in atomic form)? a. carbon b. nitrogen c. sodium d. hydrogen e. potassium f. phosphorus

Calculate the moles of each of the following samples. a. \(25.0 \mathrm{~g} \mathrm{CO}_{2}\) b. \(10.0 \mathrm{~g} \mathrm{~N}_{2} \mathrm{H}_{4}\) c. \(85.0 \mathrm{~g} \mathrm{CaF}_{2}\) d. \(15.5 \mathrm{~g} \mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\) e. \(20.0 \mathrm{~g} \mathrm{CH}_{4}\) f. \(100.0 \mathrm{~g} \mathrm{C}_{6} \mathrm{H}_{6}\) g. \(30.0 \mathrm{~g} \mathrm{Na}_{2} \mathrm{SO}_{4}\) h. \(75.0 \mathrm{~g} \mathrm{~K}_{3} \mathrm{PO}_{4}\) i. \(50.0 \mathrm{~g} \mathrm{Al}\left(\mathrm{NO}_{3}\right)_{3}\) j. \(47.2 \mathrm{~g} \mathrm{Mg}_{3}\left(\mathrm{PO}_{4}\right)_{2}\)

Calculate the mass of each of the following samples. a. \(3.5 \mathrm{~mol} \mathrm{CO}_{2}\) b. \(0.45 \mathrm{~mol} \mathrm{~N}_{2} \mathrm{H}_{4}\) c. \(2.25 \mathrm{~mol} \mathrm{CaF}_{2}\) d. \(1.75 \mathrm{~mol} \mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\) e. \(4.9 \mathrm{~mol} \mathrm{CH}_{4}\) f. \(8.75 \mathrm{~mol} \mathrm{C}_{6} \mathrm{H}_{6}\) g. \(2.35 \mathrm{~mol} \mathrm{Na}_{2} \mathrm{SO}_{4}\) h. \(0.672 \mathrm{~mol} \mathrm{~K}_{3} \mathrm{PO}_{4}\) i. \(0.95 \mathrm{~mol} \mathrm{Al}\left(\mathrm{NO}_{3}\right)_{3}\) j. \(1.15 \mathrm{~mol} \mathrm{Mg}_{3}\left(\mathrm{PO}_{4}\right)_{2}\)

What is the electron arrangement for each of the elements? a. Na b. Ne c. Be d. \(\mathrm{N}\)e. \(\underline{S}\) f. \(\mathrm{Cl}\)

How many valence electrons are in each element? a. K b. P c. F d. \(\mathrm{S}\) e. \(\mathrm{Li}\) f. B

What is the octet rule?

Define ion.

How are anions and cation the same? Different?

What is the most common ion formed from each element? a. \(\mathrm{Li}\) b. Na c. Ca d. B e. \(\mathrm{P}\) f. \(\mathrm{S}\) g. Cl h. Br

Identify the following elements. a. An ion with a \(3+\) charge and two electrons. b. An ion with a \(1-\) charge and 18 electrons. c. An ion with a \(1+\) charge and 18 electrons. d. An ion with a 3 - charge and 10 electrons.

Describe a polyatomic ion.

Which are polyatomic ions? a. \(\mathrm{NO}_{3}^{-}\) b. \(\mathrm{O}^{2-}\) c. \(\mathrm{NH}_{4}^{+}\) d. \(\mathrm{Mg}^{2+}\) e. \(\mathrm{Na}^{+}\) f. \(\mathrm{O}_{2}^{2-}\)

What element is present in all organic compounds?

Give three examples of metallic elements.

Give three examples of nonmetallic elements.

What types of elements form an ionic compound?

How do the electrons behave in the formation of an ionic bond?