Topic: Octet Rule
Octet Rule
Which ion in the ground state has the same electron confi guration as an atom of neon in the ground state?
(1) Ca2+
(2) Cl−
(3) Li+
(4) O2−
Which element tends not to react with other elements?
(1) helium
(2) hydrogen
(3) phosphorus
(4) potassium
Elements that have atoms with stable valence electron configurations in the ground state are found in
(1) Group 1
(2) Group 8
(3) Group 11
(4) Group 18
Which element is least likely to undergo a chemical reaction?
(1) lithium
(2) carbon
(3) fluorine
(4) neon
Which ion in the ground state has the same electron configuration as an atom of argon in the ground state?
(1) A13+
(2) O2−
(3) K+
(4) F−
Which group on the Periodic Table has elements with atoms that tend not to bond with atoms of other elements?
(1) Group 1
(2) Group 2
(3) Group 17
(4) Group 18
Which atom in the ground state has a stable valence electron configuration?
(1) Ar
(2) Al
(3) Si
(4) Na
Sir William Ramsey is one scientist credited with identifying the noble gas argon. Sir Ramsey separated nitrogen gas from the air and reacted it with an excess of magnesium, producing solid magnesium nitride. However, a small sample of an unreactive gas remained with a density different from the density of the nitrogen gas. Sir Ramsey identifi ed the unreactive gas as argon and later went on to discover neon, krypton, and xenon.
Compare the chemical reactivities of nitrogen gas and argon gas based on Sir Ramsey’s experiment using magnesium.
Allow 1 credit. Acceptable responses include, but are not limited to:
• The Ar in the sample did not react, and the nitrogen did.
• Magnesium reacted with the nitrogen gas, and the argon gas did not react.
• Nitrogen is more reactive.
Solid sodium chloride, also known as table salt, can be obtained by the solar evaporation of seawater and from underground mining. Liquid sodium chloride can be decomposed by electrolysis to produce liquid sodium and chlorine gas, as represented by the equation below.
2NaCl(ℓ) → 2Na(ℓ) + Cl2(g)
Identify the noble gas that has atoms with the same number of electrons as a chloride ion in table salt.
Allow 1 credit for Ar or argon.
The formulas and names of four chloride compounds are shown in the table below.
Identify the noble gas that has atoms with the same electron configuration as the metal ions in rubidium chloride, when both the atoms and the ions are in the ground state.
Allow 1 credit for Kr or krypton.
Identify the element in Period 3 that is an unreactive gas at STP.
Allow 1 credit. Acceptable responses include, but are not limited to:
• Ar
• argon
• element 18
Potassium phosphate, K3PO4, is a source of dietary potassium found in a popular cereal. According to the Nutrition-Facts label shown on the boxes of this brand of cereal, the accepted value for a one-cup serving of this cereal is 170. milligrams of potassium. The minimum daily requirement of potassium is 3500 milligrams for an adult human.
Identify the noble gas whose atoms have the same electron configuration as a potassium ion.
Allow 1 credit. Acceptable responses include, but are not limited to:
• argon
• Ar
• element 18
The Lewis electron-dot diagrams for three substances are shown below.
Identify the noble gas that has atoms with the same electron configuration as the positive ion represented in diagram 1, when both the atoms and the ion are in the ground state.
Allow 1 credit. Acceptable responses include, but are not limited to:
• argon
• Ar
Explain, in terms of atomic structure, why Group 18 elements on the Periodic Table rarely form compounds.
Allow 1 credit. Acceptable responses include, but are not limited to:
• Group 18 elements rarely form compounds because their atoms have stable electron configurations.
• Their valence shells are completely filled.
• All the elements have maximum numbers of valence electrons.
• Atoms of Group 18 have a stable octet except He, which is stable with two electrons.
Silver-plated utensils were popular before stainless steel became widely used to make eating utensils. Silver tarnishes when it comes in contact with hydrogen sulfide, H2S, which is found in the air and in some foods. However, stainless steel does not tarnish when it comes in contact with hydrogen sulfide.
In the ground state, an atom of which noble gas has the same electron configuration as the sulfide ion in Ag2S?
Allow 1 credit. Acceptable responses include, but are not limited to:
• Ar
• argon
• element 18