(i) Nucleon and nuclide (ii) Atomic number and Mass number (iii) An isotope and Avogadro's constant 2. (a)Which postulates of Dalton's atomic theory are strictly incorrect?Show why these errors didn't affect the apparent validity of the theory. (3 marks) (a) State three observations that were made from the Rutherford's alpha -particle scattering experiment and what did these observations prove about the structure of an atom? (3 mark) 3. (a) (i) The element lead (Pb) consists of four naturally occurring isotopes with masses 203.97302,205.97444,206.97587 and 207.97663 a.m.u.The relative abundances of these

(i) Nucleon and nuclide<br />(ii) Atomic number and Mass number<br />(iii) An isotope and Avogadro's constant<br /><br />2. (a) The postulates of Dalton's atomic theory that are strictly incorrect are:<br />1. Atoms of the same element are identical in mass and properties.<br />2. Atoms of different elements have different masses and properties.<br />3. Atoms combine in simple whole-number ratios to form compounds.<br /><br />These errors didn't affect the apparent validity of the theory because the theory was still able to explain the chemical behavior of substances and the formation of compounds, even though the atomic masses were not accurate.<br /><br />3. (a) Three observations made from Rutherford's alpha-particle scattering experiment are:<br />1. Most of the alpha particles passed through the gold foil without any deflection.<br />2. A small fraction of the alpha particles were deflected at large angles.<br />3. A very small fraction of the alpha particles were scattered back in the direction they came from.<br /><br />These observations proved that the atom is mostly empty space, with a small, dense, positively charged nucleus at the center.