Question

Elements in the same group of the periodic table often form compounds with similar formulas, but not always with similar properties.
For example, members of the carbon family all form dioxides. $C{O}_2,Si{O}_2,Sn{O}_2$, and $Pb{O}_2$ are all known to exist, but $C{O}_2$ consists of independent gaseous molecules, while $Si{O}_2$ is a network solid, and $Sn{O}_2$ and $Pb{O}_2$ are ionic solids.
Which of the following would not help to explain these observations?

• A. Atomic size (radius) generally increases with increasing atomic number within a group.
• B. Carbon and silicon are nonmetals, while tin and lead are metals.
• C. All four members of the carbon family have $s^2{p}^2$ valence configurations.
• D. Only carbon can readily form $\pi -$ bonds.

Answer 1

The correct option is A Atomic size (radius) generally increases with increasing atomic number within a group.

Carbon is a non-metal, silicon and germanium are metalloids, and tin and lead are metals. With $4$ valence shell electrons, elements of the carbon family tend to form covalent compounds. For example, members of the carbon family all form dioxides. ${CO}_2{,SiO}_2,{SnO}_2{CO}_2,{SiO}_2,{SnO}_2$ and ${PbO}_{2}Pb{O}_2$ are all known to exist, but ${CO}_{2}C{O}_2$ consists of independent gaseous molecules, while ${SiO}_{2}Si{O}_2$ is a network solid, and ${SnO}_{2}Sn{O}_2$ and ${PbO}_{2}Pb{O}_2$ are ionic solids.

Thus elements in the same group of the periodic table often form compounds with similar formulas, but not always with similar properties.

Thus it does not explain anything about atomic radius.