Question 1: Define the term 'atomic model' and explain its significance in the development of modern chemistry.

Answer: An atomic model is a theoretical representation of the structure of an atom. It is significant because it helps scientists understand how atoms behave and interact, leading to the development of modern atomic theory.

Question 2: Name the scientist who proposed the 'plum pudding' model of the atom and briefly describe its main feature.

Answer: J.J. Thomson proposed the 'plum pudding' model, which depicted the atom as a sphere of positive charge with negatively charged electrons embedded within it.

Question 3: Multiple Choice: Which experiment led to the rejection of the 'plum pudding' model?

Answer: a) Rutherford gold foil experiment

Question 4: Fill in the blank: Ernest Rutherford's gold foil experiment demonstrated that the atom has a tiny, dense, positively charged center called the _______.

Answer: nucleus

Question 5: Describe the main conclusion Rutherford drew from his experiment and its impact on atomic models.

Answer: Rutherford concluded that the atom's positive charge is concentrated in a small, dense nucleus at the centre, leading to the nuclear model of the atom. This challenged the earlier 'plum pudding' model and laid the foundation for the modern atomic theory.

Question 6: Calculate the number of protons in an atom of carbon-14. (Atomic number of carbon = 6)

Answer: 6

Question 7: Explain how the discovery of isotopes challenged the early atomic theory. Provide an example involving carbon isotopes.

Answer: The discovery of isotopes showed that atoms of the same element can have different numbers of neutrons, contradicting early theories that atoms of an element are identical. For example, carbon has isotopes like carbon-12 and carbon-14, which have different neutron numbers but the same number of protons.

Question 8: Identify one safety precaution that must be considered when conducting experiments related to atomic history or radioactive isotopes.

Answer: Always wear appropriate protective equipment, such as gloves and safety goggles, when handling radioactive materials.

Question 9: Data Analysis: A sample of an element's isotope mixture contains 75% of isotope A (mass number 23) and 25% of isotope B (mass number 24). Calculate the average atomic mass of the element.

Answer: 0.75 * 23 + 0.25 * 24 = 17.25 + 6 = 23.25 u

Question 10: Explain how the development of atomic models has influenced modern technology and industry.

Answer: The development of atomic models has led to advancements in nuclear energy, medical imaging, radiation therapy, and electronic devices like semiconductors. Understanding atomic structure allows for the manipulation of materials at the atomic level, enabling innovations across various industries.