Question 1: Define a proton, neutron, and electron, including their relative masses and charges.

Answer: A proton is a positively charged subatomic particle found in the nucleus with a mass of approximately 1 atomic mass unit (amu); a neutron is a neutral particle also in the nucleus with a mass close to 1 amu; an electron is a negatively charged particle orbiting the nucleus with a negligible mass (~1/1836 amu).

Question 2: Explain why isotopes of an element have the same number of protons but different numbers of neutrons.

Answer: Isotopes have the same atomic number because they have the same number of protons, but differ in their neutron count, which affects their atomic mass. This difference occurs because neutrons are not involved in chemical bonding but contribute to the nucleus's stability.

Question 3: A sample contains 12 protons, 12 neutrons, and 12 electrons. What is its atomic number, mass number, and charge?

Answer: Atomic number = 12; Mass number = 12 + 12 = 24; Charge = 0 (neutral).

Question 4: Identify the number of protons, neutrons, and electrons in a sodium-23 isotope.

Answer: Protons = 11; Neutrons = 23 - 11 = 12; Electrons = 11 (assuming neutral atom).

Question 5: Which subatomic particle determines the chemical identity of an element?

Answer: Protons.

Question 6: In an atom with 15 protons, 16 neutrons, and 15 electrons, what is the isotope's name and its atomic number?

Answer: It is an isotope of phosphorus with atomic number 15.

Question 7: Calculate the number of neutrons in an isotope with a mass number of 56 and 26 protons.

Answer: Neutrons = 56 - 26 = 30.

Question 8: Describe a practical method to separate a mixture of isotopes of the same element.

Answer: Methods such as mass spectrometry can be used to separate isotopes based on differences in their mass-to-charge ratios. This involves ionising the sample, accelerating the ions through a magnetic or electric field, and then detecting the separated isotopes for analysis.

Question 9: An element has an atomic number of 8 and a mass number of 16. What are the number of protons, neutrons, and electrons in a neutral atom of this element?

Answer: Protons = 8; Neutrons = 16 - 8 = 8; Electrons = 8.

Question 10: Explain the significance of the neutron in stabilising the nucleus of an atom.

Answer: Neutrons contribute to the strong nuclear force that holds the nucleus together and help offset repulsive electrostatic forces between protons, thus stabilising the nucleus.

Question 11: Identify the subatomic particles involved in chemical bonding and their roles.

Answer: Electrons are involved in chemical bonding, as they are shared or transferred between atoms, forming covalent or ionic bonds.

Question 12: Describe how the discovery of isotopes has impacted our understanding of atomic structure.

Answer: The discovery of isotopes revealed that atoms of the same element can have different numbers of neutrons, leading to variations in atomic mass. This understanding has improved models of atomic structure, explained phenomena like isotopic labelling, and advanced techniques such as mass spectrometry, influencing fields from chemistry to medicine.