Atoms and Isotopes Flashcards
Explain the basic structure of an atom.
An atom is composed of a positively charged nucleus composed of both protons and neutrons surrounded by negatively charged electrons.
Explain arrangement of electrons in space and how this can be changed.
The electrons are arranged at different distances from the nucleus (different energy levels). The electron arrangements may change with the absorption of electromagnetic radiation (move further from the nucleus; a higher energy level) or by the emission of electromagnetic radiation (move closer to the nucleus; a lower energy level).
What is an isotope?
An isotope is an atom of the same element with a different number of neutrons.
Explain how the discovery of the electron changed how atoms were thought of.
Before the discovery of the electron, atoms were thought to be tiny spheres that could not be divided. The discovery led to the plum pudding model of the atom, consisting a positively charged solid sphere with electrons embedded randomly.
How did Rutherford’s discoveries alter the plum pudding model of the atom?
Rutherford concluded from his alpha particle scattering experiment that the mass of an atom is concentrated at the centre in a positively charged nucleus.
What did Niels Bohr contribute to the atomic model?
Bohr suggested that electrons orbit the nucleus at specific distances. His theoretical calculations agreed with experimental observations.
Who proved the existence of neutrons within the atom (specifically in the nucleus)?
James Chadwick
