Understanding Compounds and Atomic Theory

The lecture introduces atomic theory, starting with Dalton's ideas about atoms and compounds. It explains chemical changes, the law of definite proportions, and how compounds form in fixed ratios. The mass of electrons is discussed through Thompson's and Millikan's experiments. Rutherford's experiment reveals the atom's structure, highlighting the nucleus and empty space. Isotopes and their discovery are also covered, emphasizing their chemical similarity but mass difference.

According to Dalton's atomic theory, what is the smallest unit that retains the properties of an element?

• Atom

• Molecule

• Compound

• Electron

What happens to atoms during a chemical reaction according to Dalton's theory?

• They are rearranged

• They are created

• They change into energy

• They are destroyed

How do compounds differ from elements?

• Compounds are formed by elements in fixed ratios

• Compounds have variable compositions

• Compounds are mixtures of elements

• Compounds are made of one type of atom

What does the law of definite proportions state about the composition of a compound?

• It changes with pressure

• It depends on the amount of substance

• It varies with temperature

• It is always in a fixed ratio

What does the law of multiple proportions explain?

• Elements combine in small whole number ratios

• Elements combine in fixed mass ratios

• Elements combine in any ratio

• Elements combine in fractional ratios

Which experiment helped determine the charge of an electron?

• Rutherford's gold foil experiment

• Dalton's atomic theory

• Millikan's oil drop experiment

• Thompson's cathode ray experiment

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

• Electrons orbit in fixed paths

• Atoms are indivisible

• Atoms have a dense nucleus

• Atoms are solid spheres

Which model suggested that electrons are embedded in a positively charged mass?

• Bohr model

• Plum pudding model

• Rutherford model

• Quantum model

What is an isotope?

• An atom with a different number of protons

• An atom with a different number of electrons

• An atom with a different number of neutrons

• An atom with a different number of molecules

What distinguishes isotopes of the same element?

• Number of electrons

• Number of molecules

• Number of protons

• Number of neutrons