Atoms, elements and compounds - Atomic structure and the Periodic Table (3)
Resources |
Revision Questions |
Chemistry
Login to see all questions
Click on a question to view the answer
1.
Explain, in terms of the number of protons, how isotopes of an element differ, yet still represent the same element.
Isotopes are atoms of the same element, meaning they have the same number of protons (and therefore the same atomic number). However, isotopes differ in the number of neutrons in their nucleus.
Because isotopes have the same number of protons, they are defined as the same element. The difference in the number of neutrons leads to variations in their mass number. For example, Carbon-12 (12C) and Carbon-14 (14C) are isotopes of carbon; both have 6 protons, but 12C has 6 neutrons and 14C has 8 neutrons.
2.
Define mass number and nucleon number as they relate to the nucleus of an atom. Explain the significance of these terms in atomic notation.
Definition: The mass number and nucleon number are terms used synonymously to describe the total number of protons and neutrons present in the nucleus of an atom.
Significance in Atomic Notation: The mass number is represented by the subscript 'A' in the atomic notation of an element (e.g., 231Na). The subscript '1' represents the number of protons (atomic number), and the superscript '23' represents the mass number (number of protons + neutrons).
- Mass Number (A): Represents the total number of nucleons (protons + neutrons).
- Nucleon Number: A synonym for mass number, referring to the total number of protons and neutrons.
3.
A student is describing the composition of an atom. Which of the following statements is correct regarding the relative charges and masses of protons, neutrons and electrons?
- A. Protons have a negative charge and a mass of 0. Neutrons have a positive charge and a mass of 1. Electrons have no charge and a mass of 1.
- B. Protons have a positive charge and a mass of 1. Neutrons have no charge and a mass of 0. Electrons have a negative charge and a mass of 0.
- C. Protons have a positive charge and a mass of 1. Neutrons have no charge and a mass of 1. Electrons have a negative charge and a mass of 0.
- D. Protons have a negative charge and a mass of 1. Neutrons have a positive charge and a mass of 0. Electrons have a positive charge and a mass of 0.
Correct Answer: C
Explanation: Protons have a positive charge (+1) and a mass of 1. Neutrons have no charge (0) and a mass of 1. Electrons have a negative charge (-1) and a mass of 0. Option C accurately reflects these properties.