10220 - Mass of atoms.ppt

Mass of an atom Mass of an atom Each atom weighs about 0.00000000000000000000001 g which is too small to be handled effectively by using metric scale. Mass (質量) Isotopic Mass (同位素質量) Atomic Mass (原子質量) Electronic arrangement (電子組態) Periodic Table (周期表) Atomic number(原子序) Definitions of Atomic no.(Z) and Mass no.(A) Atomic number (Z) = number of proton Mass number (A) = number of proton + number of neutron For an uncharged atom : No. of proton = atomic number No. of neutron = mass number - no. of proton (atomic number) No. of electron = no. of proton = atomic number Isotope – atoms of the same element with different masses Use of symbols Glossary (詞彙) Isotopes (同位素) – atoms of the same element but with different masses. (Relative) Isotopic mass ((相對)同位素質量) – mass of an isotope with respect to 12C isotope. (Relative) Atomic mass ((相對)原子質量) – weighted average of isotopic masses for an specific element. Relative (natural) abundance (相對(自然)豐度) – Percentage amount in the nature. Isotope (同位素) Isotope – atoms of the same element with different masses Evolution of Universe Measurement of Mass Standard mass used in metric scale (十進制) Carbon-12 Scale (度量衡/標度) Are they good for measuring the masses in atomic world ? Pauls Fruit Store I have decided to set each equivalent weight of lemon of pineapple at the price of $12. Carbon-12 Scale Each carbon-12 isotope weighs about 0.0000000000000000000000199 g which is too small to be handled effectively by using metric scale. In Carbon-12 Scale, each carbon-12 isotope is defined arbitrarily to have a mass of 12 units. (or just 12 / 12 a.m.u.)a.m.u. = atomic mass unit (Relative) Isotopic Mass based on carbon-12 scale (Relative) Isotopic Mass based on carbon-12 scale (Relative) Atomic Mass (Relative) Atomic Mass (Relative) Atomic Mass (Relative) Atomic Mass (Relative) Atomic Mass Glossary (詞彙) Atomic number (原子序) – no. of proton in a particle. Mass number (質量數) – sum of no. of proton and no. of neutron in a particle. Isotopes