why are sodium (Na) and potassium (K) in the same group on the periodic table?

they are both colorless
they are both hard and brittle
they have similar atomic weights
they have similar reactivity

3 answers

Sodium (Na) and potassium (K) are in the same group on the periodic table because they have similar properties and electronic configurations.

1. They have similar reactivity: Both sodium and potassium belong to the alkali metal group, which is the first column on the periodic table. Alkali metals are highly reactive and easily lose their outermost electron to form a positive ion. Sodium and potassium readily react with water and oxygen to form their respective hydroxides and oxides.

2. They have similar atomic weights: Sodium and potassium have atomic weights that are close to each other. Sodium has an atomic weight of 22.99 g/mol, while potassium has an atomic weight of 39.10 g/mol. The similarity in atomic weights reflects the trend of increasing atomic weights as one moves down a group on the periodic table.

3. They have similar physical properties: Both sodium and potassium are soft metals that can be cut with a knife. They have relatively low melting and boiling points and are excellent conductors of electricity. However, it is worth noting that sodium and potassium are not colorless; they have distinctive colors. Sodium gives a yellow color when exposed to a flame, while potassium produces a lilac or violet flame.

Overall, the similarities in reactivity, atomic weights, and physical properties place sodium and potassium in the same group on the periodic table.
what is the right answer

they are both colorless

they are both hard and brittle

they have similar atomic weights

they have similar reactivity
The correct answer is:

- They have similar atomic weights
- They have similar reactivity

Sodium (Na) and potassium (K) have similar properties and electronic configurations, making them belong to the same group, but the other provided statements are not accurate.

- Sodium is not colorless; it gives a yellow color when exposed to a flame, while potassium produces a lilac or violet flame.
- Sodium and potassium are not hard and brittle; they are relatively soft metals that can be easily cut with a knife.