Which of the following properties is NOT a characteristic of the first column Group 1A elements (alkali metals)?
A) They are shiny.
B) They are good conductors of heat.
C) They react vigorously with water.
D) Most of them are liquids at room temperature.
E) They are good conductors of electricity.
The correct answer and explanation is :
The correct answer is D) Most of them are liquids at room temperature.
Explanation:
Group 1A elements, also known as alkali metals, include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). These metals share several key properties that distinguish them from other elements in the periodic table:
A) They are shiny: Alkali metals are indeed shiny when freshly cut. Their luster diminishes quickly because they oxidize and tarnish when exposed to air, forming a layer of oxide. However, in their pure form, they are typically shiny.
B) They are good conductors of heat: Alkali metals are excellent conductors of heat. Like most metals, they have a high thermal conductivity, which means they can efficiently transfer heat.
C) They react vigorously with water: Alkali metals are known for their vigorous and often violent reactions with water. As you go down the group, the reactivity increases. For example, sodium reacts with water to produce hydrogen gas and heat, and potassium reacts even more intensely. This reactivity is due to their low ionization energies, which allow them to easily lose their outermost electron.
D) Most of them are liquids at room temperature: This statement is incorrect. The alkali metals are all solid at room temperature, except for francium, which is extremely rare and radioactive. The only alkali metal that has a relatively low melting point (around 28°C) is cesium, but it is still a solid at room temperature. Therefore, it is not true that most of the alkali metals are liquids at room temperature.
E) They are good conductors of electricity: Alkali metals are also good conductors of electricity. This is because they have free-moving valence electrons, which can carry charge through a conductive material.
Thus, the property that does not describe alkali metals is D, as most of them are solid at room temperature, not liquid.