Potassium and lithium are Group 1 metals that exist as isotopes.
Complete the table of information about two isotopes of potassium.
| Atomic number | Mass number | Number of protons | Number of neutrons |
|---|---|---|---|
| 19 | 39 | ||
| 19 | 22 |
A sample of lithium has this percentage composition by mass:
6Li=7.5%7Li=92.5% ^{6}\text{Li} = 7.5\% \qquad ^{7}\text{Li} = 92.5\% 6Li=7.5%7Li=92.5%Use this information to calculate the relative atomic mass of lithium. Give your answer to one decimal place.
A reaction occurs when a small piece of potassium is added to water in a trough. State two observations that could be made during the reaction.
A few drops of phenolphthalein are added to the liquid in the trough at the end of the reaction. A colour change occurs.
State the final colour of the liquid in the trough.
Give the formula of the ion formed during the reaction that causes this colour change.
The electronic configurations of lithium and potassium are
Li2,1K2,8,8,1 \text{Li} \quad 2,1 \qquad \text{K} \quad 2,8,8,1 Li2,1K2,8,8,1Explain why potassium is more reactive than lithium.
