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level: Atomic Structure

Questions and Answers List

level questions: Atomic Structure

QuestionAnswer
What is the radius of the an Atom & a NucleusAtom's radius = 1 × 10^-10 m Radius of a Nucleus =1 × 10^-14 m
What are the Charges and Masses of the Subatomic Particles?View Image:
What is the Atomic Number?The number of protons in an atom (this defines what element an element is)
What is the Mass Number?Protons + Neutrons
What are isotopes?Atoms of the same element with a different number of neutrons (same atomic no. but different mass no.)
What does the electron determine?An elements chemical properties
Whats the relative atomic mass?average mass of the atoms of the isotopes, calculated from: - the mass numbers of its isotopes - the abundance(plentifulness) of these isotopes
What did John Dalton do?JOHN DALTON: 1- Published his ideas in 1803 2- All matter was made of tiny spheres that cant be divided - atoms JJ THOMSON: 1- Nearly 100 years later, discovered electrons 2- Plum pudding model: ball of + charge, - electrons embedded ERNEST RUTHERFORD: 1- Positive charged alpha particles fired at thin gold foil 2- most went through: mostly empty space 3- few scattered in all directions: positively charged nucleus concentrated at atoms centre NIELS BOHR: 1- Did calculations& experiments: electrons orbit the nucleus in shells at fixed distances FURTHER EXPERIMENTS: 1- Protons: positive charge JAMES CHADWICK: 1- 1932, found evidence for mass in nucleus with no charge - neutrons