Question 1: What are noble gases?
Solution: Noble gases are elements in Group 18 of the periodic table. They include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). They are characterized by their full electron shell and low reactivity.
Question 2: Why are noble gases unreactive?
Solution: Noble gases are unreactive because their outermost electron shell is full. This electron configuration is very stable, and thus they have little tendency to gain or lose electrons, making them rarely involved in chemical reactions.
Question 3: What are the uses of helium?
Solution: Helium is commonly used in balloons and airships as it is lighter than air. It’s also used in cooling systems for superconducting magnets, due to its low boiling point, and in the gas mixtures for deep-sea diving, due to its low solubility in blood.
Question 4: Which noble gas is radioactive?
Solution: Radon (Rn) is the only noble gas that is radioactive. It is formed as a decay product of uranium and thorium.
Question 5: How do the boiling points of noble gases change down the group?
Solution: The boiling points of noble gases increase down the group. This is because the atomic size increases down the group, which increases the strength of the London dispersion forces, making it harder for the atoms to separate from each other.
Question 6: What is the lightest noble gas?
Solution: The lightest noble gas is helium (He), with an atomic number of 2 and an atomic mass of approximately 4.
Question 7: Which noble gas has the largest atomic radius?
Solution: Radon (Rn) has the largest atomic radius among the noble gases. Atomic radius generally increases down a group in the periodic table.
Question 8: Which noble gas is used in “neon” advertising signs?
Solution: The noble gas neon (Ne) is used in “neon” advertising signs. When an electric current is passed through it, it glows with a bright orange-red light.
Question 9: What is the most abundant noble gas in the Earth’s atmosphere?
Solution: The most abundant noble gas in the Earth’s atmosphere is argon (Ar), accounting for approximately 0.93% of the atmosphere by volume.
Question 10: What are the uses of argon?
Solution: Argon is commonly used as an inert shielding gas in welding and other high-temperature industrial processes where ordinarily non-reactive substances become reactive. It’s also used in incandescent and fluorescent lighting, and other types of gas discharge tubes.
Question 11: What is the oxidation state of noble gases?
Solution: Noble gases traditionally have an oxidation state of 0 in their elemental state because they have full electron shells and do not typically form chemical compounds. However, some noble gases can form compounds under specific conditions, in which they may have different oxidation states.
Question 12: What noble gas is used in lasers?
Solution: Several noble gases are used in lasers, including helium (He), neon (Ne), and argon (Ar). Their specific use depends on the type of laser and its desired properties.
Question 13: Why is helium used in breathing mixtures for deep-sea divers?
Solution: Helium is used in breathing mixtures for deep-sea divers to prevent nitrogen narcosis, a condition that can occur when divers breathe regular air under high pressure underwater. Helium is not absorbed into the body tissues under pressure like nitrogen is, and so does not have the narcotic effects of nitrogen.
Question 14: Can noble gases form compounds?
Solution: Yes, noble gases can form compounds, though it is not common. The first noble gas compound was xenon hexafluoroplatinate (XePtF₆), discovered in 1962. Since then, compounds of xenon, krypton, and argon have been discovered.
Question 15: What is the heaviest noble gas?
Solution: The heaviest noble gas is radon (Rn), with an atomic number of 86.
Question 16: Why are noble gases used in lighting?
Solution: Noble gases are used in lighting because they glow when an electric current is passed through them. The color of the light depends on the gas used. For example, neon glows red-orange, while argon produces a lavender light.
Question 17: What is the electron configuration of noble gases?
Solution: Noble gases have full electron shells. For example, helium has 2 electrons in its only energy level, while neon has 2 electrons in the first energy level and 8 in the second. This pattern continues, with each noble gas having 8 electrons in its outermost energy level (except for helium, which only has two because it’s the first level).
Question 18: Are noble gases metals, nonmetals, or metalloids?
Solution: Noble gases are nonmetals. They are located on the rightmost column of the periodic table, which contains only nonmetals.
Question 19: What is the trend in atomic radii for noble gases?
Solution: The atomic radii of noble gases increase down the group. This is because each successive element down the group has an additional electron shell compared to the one above it.
Question 20: What type of bonds can noble gases form?
Solution: Noble gases can form covalent bonds in certain compounds. For example, in xenon hexafluoride (XeF₆), the xenon atom forms covalent bonds with six fluorine atoms. However, such compounds are not common because noble gases are generally unreactive due to their stable electron configurations.
