In the development of the modern model of atomic structure, Henry Moseley analysed the high-energy characteristic X-ray spectra of various elements. He discovered a linear relationship between the square root of the frequency of the characteristic X-rays ( $f\sqrt{f}$ ) and the atomic number ( $Z$ ).

Which of the following describes how this discovery refined Mendeleev's periodic table and resolved anomalies such as the tellurium-iodine or argon-potassium pairs?

It established that atomic mass is proportional to the number of orbital electrons, confirming that Mendeleev’s mass-based sequence was fundamentally correct but required more precise mass measurements.

It demonstrated that the fundamental organizing principle of the elements is the nuclear charge ( $Z$ ) rather than atomic mass, placing elements in an order that naturally matched their chemical properties.

It proved that elements are defined by their mass number ( $A$ ), showing that the anomalies were due to the existence of isotopes with different numbers of orbital electrons.

It showed that the periodic properties depend on the neutron-to-proton ratio ( $N / Z$ ), meaning elements with the same specific charge must be grouped together.

Which of the following describes how this discovery refined Mendeleev's periodic table and resolved anomalies such as the tellurium-iodine or argon-potassium pairs?

It proved that elements are defined by their mass number ( $A$ ), showing that the anomalies were due to the existence of isotopes with different numbers of orbital electrons.

It showed that the periodic properties depend on the neutron-to-proton ratio ( $N / Z$ ), meaning elements with the same specific charge must be grouped together.

Atomic structure

Question 26

Markscheme

Atomic structure

Question 26

Markscheme

Atomic structure

Question 26

Atomic structure Questions

Atomic structure

Question 26

Atomic structure Questions