Question 1: Define an atom and explain its significance in chemistry.

Answer: An atom is the smallest unit of an element that retains its chemical properties; it is the basic building block of matter.

Question 2: Describe the main contribution of J.J. Thomson to atomic theory.

Answer: J.J. Thomson discovered the electron and proposed the 'plum pudding' model of the atom, where electrons were embedded in a positive sphere.

Question 3: What was the key finding of Rutherford's gold foil experiment?

Answer: Rutherford's experiment showed that atoms have a small, dense nucleus at the center, with electrons orbiting around it.

Question 1: Calculate the number of protons, neutrons, and electrons in an atom of Carbon-14.

Answer: Protons: 6; Neutrons: 8; Electrons: 6

Question 2: If an atom has 11 protons, 12 neutrons, and 11 electrons, what is its atomic mass number?

Answer: 23

Question 1: Identify two safety precautions that should be taken when conducting experiments involving radioactive isotopes.

Answer: Use proper shielding and wear protective equipment such as gloves and safety goggles.

Question 2: Explain how the discovery of the electron changed previous atomic models.

Answer: The discovery of the electron proved that atoms are divisible and contained subatomic particles, leading to models like the 'plum pudding' and ultimately modern atomic models with a nucleus and electrons.

Question 1: A series of experiments measured the deflection of alpha particles passing through a thin foil. The majority of particles passed straight through, but some were deflected at large angles. What conclusions can be drawn about the structure of the atom?

Answer: Most of the atom is empty space, with a small, dense, positively charged nucleus causing large deflections.

Question 2: Data shows that isotopes of an element have the same number of protons but different neutrons. How does this support the concept of isotopes?

Answer: It demonstrates that isotopes are atoms of the same element with identical proton numbers but varying neutron numbers.

Question 1: Describe how Rutherford’s model of the atom contributed to the development of modern atomic theory.

Answer: Rutherford's model introduced the concept of a central nucleus and empty space surrounding it, which laid the foundation for the modern quantum mechanical model of the atom, influencing subsequent discoveries about atomic structure.

Question 2: Explain how understanding atomic structure is important in industries such as medicine or energy production.

Answer: Knowledge of atomic structure allows industries to develop nuclear medicines, energy sources like nuclear power, and materials with specific properties, leading to technological advancements and safer practices.