Why are sodium (Na) and potassium (K) in the same group on the periodic table?
They are both colorless.
They are both colorless.
They have similar reactivity.
They have similar reactivity.
They have similar atomic weights.
They have similar atomic weights.
They are both hard and brittle.
They are both hard and brittle.
Sodium (Na) and potassium (K) are not both colorless, as you mentioned twice. In fact, sodium is usually silver-white or yellowish in color, while potassium is a soft silvery-white metal. So the statement "They are both colorless" is incorrect.
However, the other three statements are correct:
1. They have similar reactivity: Sodium and potassium lie in the same group (Group 1) on the periodic table, also known as the alkali metals. These elements share similar chemical properties, such as high reactivity with water and oxygen.
2. They have similar atomic weights: Sodium has an atomic weight of approximately 23 atomic mass units (amu), while potassium has an atomic weight of about 39 amu. Although not exactly the same, their atomic weights are close, which contributes to their similarity in chemical behavior.
3. They are both hard and brittle: This statement is incorrect. Both sodium and potassium are soft metals that can be easily cut with a knife. They have relatively low melting points and are quite malleable, meaning they can be shaped or flattened under pressure.
In summary, while the statement about colorlessness is incorrect, sodium and potassium are in the same group on the periodic table due to their similar reactivity and approximate atomic weights. However, they are not hard and brittle, rather they are soft and malleable metals.
The reason sodium (Na) and potassium (K) are in the same group on the periodic table is because they share some similar chemical properties. There are several ways to determine this similarity.
First, they are both colorless. However, color is not a defining characteristic for determining group placement on the periodic table, as there are many elements with different colors in the same group.
Second, they have similar reactivity. Both sodium and potassium are highly reactive metals and readily react with water and oxygen to form hydroxides and oxides respectively. This similarity in reactivity indicates that they have similar chemical behavior.
Third, they have similar atomic weights. Sodium has an atomic weight of approximately 23 and potassium has an atomic weight of approximately 39. Their proximity in atomic weight indicates that they have similar electronic configurations and, therefore, similar chemical properties.
Lastly, it is important to note that hardness and brittleness are not decisive factors for determining group placement on the periodic table. Sodium and potassium, in fact, have quite different physical properties in terms of hardness and brittleness. Sodium is a soft metal that can be easily cut with a knife, while potassium is even softer. Therefore, hardness and brittleness are not relevant criteria for placing sodium and potassium in the same group on the periodic table.