5.1.1 The atom (3)
Resources |
Revision Questions |
Physics
Login to see all questions
Click on a question to view the answer
1.
Describe how the scattering of alpha (α) particles by a sheet of thin metal supports the nuclear model of the atom, by providing evidence for: (c) a nucleus that is positively charged
The positive charge of the nucleus is evidenced by the electrostatic repulsion between the positively charged alpha particles and the positively charged protons within the nucleus. As alpha particles approach the nucleus, they experience a strong electrostatic force that causes them to deflect. The direction and magnitude of the deflection are directly related to the strength of the electrostatic force. The fact that the alpha particles are deflected, and often change direction significantly, indicates that they are interacting with a positive charge. This repulsion is consistent with the model of a positively charged nucleus.
- The deflection of alpha particles demonstrates the presence of a repulsive electrostatic force.
- The direction of deflection is away from the nucleus, indicating a positive charge.
- The energy loss of alpha particles upon interaction is due to the electrostatic interactions.
2.
Atoms can form ions. Explain, in terms of the number of protons, electrons and neutrons, how a positively charged ion (cation) is formed. Include a diagram to illustrate your explanation.
A positively charged ion (cation) is formed when an atom loses one or more electrons. Atoms have a positive nucleus containing protons and a negative charge due to orbiting electrons. The number of protons in the nucleus defines the element. When an atom loses electrons, it has more protons than electrons, resulting in a net positive charge. The atom has become a cation. The number of electrons lost determines the charge of the ion. For example, if an atom loses one electron, it becomes a +1 ion (cation); if it loses two electrons, it becomes a +2 ion, and so on.
Diagram:
[Image missing: Ion Formation Diagram]
3.
Describe the structure of an atom, including the location and charge of the nucleus and electrons. Explain the fundamental forces involved in maintaining this structure.
An atom is the basic building block of matter. At its centre lies the nucleus, which is a dense, positively charged region. The nucleus is composed of protons, which carry a positive charge (+1), and neutrons, which have no charge (neutral).
Orbiting the nucleus are electrons, which are negatively charged (-1). These electrons exist in specific energy levels or shells around the nucleus. The number of electrons in a neutral atom is equal to the number of protons in the nucleus, resulting in a balanced overall charge.
The positive charge of the nucleus attracts the negatively charged electrons, holding them in orbit. This electrostatic attraction is the primary force maintaining the atom's structure. The strong nuclear force holds the protons and neutrons together within the nucleus, overcoming the electrostatic repulsion between the positively charged protons.