Early pioneers in chemistry contributed significantly to our understanding of atomic structure and the organization of the Periodic Table.
Explain which block in the Periodic Table magnesium belongs to.
A sample of magnesium, Ar=24.305A_r = 24.305Ar=24.305, is found to consist of three isotopes. The accurate relative isotopic masses and % abundances of two of the isotopes are shown in the table:
| Isotope | Relative isotopic mass | % abundance |
|---|---|---|
| 24Mg^{24}\text{Mg}24Mg | 23.98523.98523.985 | 78.99%78.99\%78.99% |
| 25Mg^{25}\text{Mg}25Mg | 24.98624.98624.986 | 10.00%10.00\%10.00% |
Determine the relative isotopic mass of the third isotope of magnesium, 26Mg^{26}\text{Mg}26Mg, in the sample. Give your answer to 5 significant figures.
A student adds potassium oxide to water in a beaker. In a separate beaker, the student adds magnesium oxide to water.
Write the equation for the reaction of potassium oxide with water. State symbols are not required.
Suggest the approximate pH of the two solutions formed in the beakers.
199 exam-style questions on OCR A A Level Chemistry Atoms and reactions, covering Atomic structure and isotopes, Compounds, formulae and equations, Amount of substance, Acids, and Redox. Each one has a worked solution and a mark scheme showing where the marks go.