Deduce the number of electrons, neutrons and protons in one atom of the potassium isotope shown: $^{40}_{19}\text{K}$.
Complete the chemical equation for potassium reacting with water to produce potassium hydroxide and a gas that gives a pop with a lighted splint. $\text{2K} + \ldots\text{H}_2\text{O} \rightarrow \text{2KOH} + \ldots$
Complete the table by predicting sodium's melting point and potassium's relative hardness.
Predict the physical state of potassium at $100^\circ\text{C}$. State a reason for your answer.
Explain how this equation demonstrates that bromine is more reactive than iodine. $\text{Br}_2 + 2\text{KI} \rightarrow 2\text{KBr} + \text{I}_2$
State the colour of aqueous iodine.
State the meaning of the term diatomic.
Choose the word that best describes a substance which evaporates easily. Options: conductor, flammable, malleable, volatile.