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

Answer: A proton is a positively charged particle found in the nucleus with a mass of approximately 1 atomic mass unit (amu). A neutron is a neutral particle in the nucleus with a similar mass to a proton, about 1 amu. An electron is a negatively charged particle orbiting the nucleus with a negligible mass compared to protons and neutrons.

Question 2: Explain how the number of protons determines the element's identity.

Answer: The number of protons in an atom's nucleus, known as the atomic number, uniquely identifies the element. For example, all atoms with 6 protons are carbon atoms.

Question 1: Calculate the number of neutrons in an isotope of carbon-14, given that the atomic number of carbon is 6.

Answer: Number of neutrons = Mass number - Atomic number = 14 - 6 = 8 neutrons.

Question 2: An atom has 11 protons, 12 neutrons, and 11 electrons. What is its mass number and atomic number?

Answer: Mass number = 11 + 12 = 23; Atomic number = 11.

Question 1: Describe a simple experiment to demonstrate the presence of electrons in atoms, including safety precautions.

Answer: A common experiment involves using cathode ray tubes to observe electron flow. Students should ensure the tube is properly grounded, avoid direct contact with electrical components, and handle the tube carefully to prevent breakage and exposure to glass and electrical hazards.

Question 1: Identify the isotopes and explain the significance of their neutron numbers.

Answer: The isotopes are Chlorine-35 (17 protons + 18 neutrons) and Chlorine-37 (17 protons + 20 neutrons). The neutron number affects isotope stability and atomic mass but does not change the element's identity.

Question 1: Describe how the atomic number and mass number differ, and how they are used to distinguish isotopes.

Answer: The atomic number is the number of protons in an atom's nucleus and defines the element. The mass number is the total number of protons and neutrons. Isotopes of the same element have the same atomic number but different mass numbers due to differing neutron counts.

Question 2: A sample contains 20 protons, 20 neutrons, and 20 electrons. What is the element, its isotope name, and its charge?

Answer: Element: Calcium; Isotope: Calcium-40; Charge: Neutral (0).

Question 1: Describe how understanding isotopes is important in medical imaging or radiocarbon dating.

Answer: Isotopes like radioactive carbon-14 are used in radiocarbon dating to determine the age of archaeological samples. In medical imaging, isotopes such as technetium-99m help in detecting and diagnosing diseases due to their radioactive properties.