atomic structure question and answer Flashcards
what did john dalton think atoms were like
smooth, hard balls that could not be broken down into smaller pieces
why might a theory, such as dalton’s atomic theory change over time
as advances are made in scientific technology, new and additional evidence may require that a theory be modified
what was the major change to dalton’s theory
the knowledge that atoms are made of even smaller parts
which particle of the atom was the first to be proposed an named
the electron
thompson described an atom as having electrons scattered throughout a ball of positive charge, much like seeds in a watermelon, can you think of another model that would describe thompson’s concept of an atom
chocolate chip cookie dough
rutherford aimed a beam of positively charged particles at a thin sheet of gold foil to determine whether Thompson’s model of the atom was correct. what should have happened if Thompson’s model really had been correct
most of the charged particles would have passed straight through the foil (like what happened), but some would have bent or been deflected slightly because the positive charge was thought to be spread out
in rutherford’s gold foil experiment about 1 in 8000 particles was deflected and the rest passed through the foil. what does this tell you about the structure of gold atoms ?
that they are mostly empty space
after the electron, which was the next particle that was proposed and named
the proton
whose model first introduced protons
rutherford’s model
rutherford’s model of the atom was much like a cherry- the pit modeled the nucleus and the rest of the fruit was space taken up by electrons. can you think of another model that would describe Rutherford’s concept of the atom
a peach
how did Bohr change rutherford’s model
he proposed that electrons were in specific orbit around the nucleus
bohr’s model of the atom was much like planets orbiting the sun or rings of a tree. can you think of another model that would describe Bohr’s concept of the atom
onion
how does the development of the atomic models illustrate the scientific process
Each model was proposed to explain observations & to correct inaccuracies in older models that were revealed as a result of experimentation
what is our current model of the atom called . describe this model `
electron cloud model –electrons move rapidly within a cloudlike region around the nucleus
what is the major difference between our current model of the atom and Bohr’s model of the atom
in the cloud model, electrons do not orbit the nucleus like planets
what is the center of an atom called
the nucleus
what particles are found in the nucleus
protons and neutrons
where are electrons found
in the cloud like region around the nucleus
who discovered the neutron, why was it so hard the find
james chadwick, because it has no electric charge
what makes an atom neutral
equal numbers of protons and neutrons causes the positive and negative charges to cancel each other out
how do atoms of one element differ from atoms of another element
number of protons
what particles make up an atom? Make sure the include the charge and location of each particle
protons- positive-nucleus
electrons-negative- electron cloud
neutron- no charge- nucleus
explain why scientists use models to study atoms
because atoms are so small
what two particles account for almost all the mass of an atom
protons and neutrons
