revision topic 1 Flashcards
who was the first person that had strong experimental evidence about the atom?
john dalton
how did john dalton describe the atom?
he describes them as tiny hard spheres
what did john dalton believe about the atom?
include 3 points
he believed that each chemical had its own atom that differed from other atoms masses, he also believed that an atom couldn’t be split nor divided, and also he believed that in chemical reactions the atoms rearrange themselves and combine with each other to form other different and new atoms
who discovered the electron
J.J Thomson
how did J.J Thomson discover electrons
by applying low voltages to gages at low pressure
what model did J.J Thomson offer and why?
he offered the plum pudding model because after the test he ran he realized that the particles are attracted to positive particles making them negative, he said that the negative particles must have come from the tube he was testing on making him come to the conclusion that the negative electrons are embedded in a cloud of positive protons
what is Ernest Rutherford’s experiment, his results, and his analysis
his students shot heavily dense alpha particle at a thin gold foil, he was surprised that some of the alpha particles were deflected back to the source so he put J.J Thomson model under review as he proposed another model which says that each atom has a nucleus that contains positive protons and has most of the atoms mass, and he said that the electrons are orbiting the nucleus in set shells
explain Bohr updated atom model
Bohr noticed that the light gave out when the atoms were heated hand specific amounts of energy, so he suggested the electrons are orbiting in set distances, in fixed shells
who discovered the neutrons?
James Chadwick
What’s an element?
a chemical substance that is only made from one atom
what is a compound?
a chemical substance that is made by more than one atoms that are chemically bonded
what is an isotope?
an element that has the same number of protons but a different number of neutrons, so it has the same chemical properties but different physical properties
