Movement of electrons about a central nucleus is a concept by: Chadwick Bohr Mendeleev Dalton Thomson

The correct answer is **Bohr**.<br /><br />The concept of electrons moving around a central nucleus in specific orbits or energy levels was proposed by **Niels Bohr** in his atomic model, known as the **Bohr Model**. This model refined earlier atomic theories and introduced the idea that electrons travel in discrete energy levels (or shells) around the nucleus, which explained atomic spectra.<br /><br />### Explanation of Other Options:<br />1. **Chadwick**: Discovered the neutron in 1932.<br />2. **Mendeleev**: Created the periodic table of elements based on atomic mass.<br />3. **Dalton**: Proposed the atomic theory, stating that atoms are indivisible particles.<br />4. **Thomson**: Discovered the electron and proposed the "plum pudding" model of the atom.<br /><br />