Flashcards
Atomic Structure
Cards in this deck (14)
- 1What did John Dalton say about the electronic structure?he agreed with Democritus that matter was made up of tiny spheres that couldn't be broken up, but thought each element was made up of different atoms
- 2Who discovered that Dalton's theory wasn't correct?JJ Thompson, who said electrons could be removed from atoms
- 3What did Thomas suggest after he disproved Dalton's theory?Atoms were spheres of positive charges with tiny negative electrons stuck in them like plums in a plum pudding
- 4Who disproved Thomas' theory? How?Rutherford and Marsden fired a beam of alpha particles at thin gold foil, expecting the particles to deflect slightly
- 5What actually happened in Rutherford and Marsden's experiment?most of the alpha particles went straight thru the gold, but the odd one reflected
- 6What did Rutherford and Marsden's experiment show?Most of the mass of an atom was concentrated at the center in a tiny nucleus and the nucleus must have a positive charge, since it repelled positive alpha particles. It also showed most of the atom was empty space
- 7Why were some of the alpha particles deflected and some went thru?The ones that were deflected had gone straight into the nucleus, which would have repelled the particles as they were both positive. The particles that went straight thru missed the nucleus entirely and the ones that went thru but slightly left or right had passed by the nucleus
- 8What two things did Rutherford and Marsden summarize in their experiment?1) The nucleus in tiny but it makes up most of the mass of the atom. It has a positive charge
2) The rest of the atom is mostly empty space, but with negative electrons floating around the nucleus - 9What is the mass of a proton, neutron and electron?P=1
N=1
E= Negligible - 10What is the charge of a proton, neutron and electron?P=+1
N=0
E=-1 - 11What is the number of protons the same as?The number of neutrons
- 12What charge do atoms have overall?No charge
- 13Why will the number of protons be the same as the number of electrons in a neutral atom?Because the charge on an electron is the same size as the charge on a proton
- 14How does an atom become an ion?If some electrons are added or removed, which give the ion a charge