atomic theory Flashcards
what is an atom?
the smallest particle of an element that give the element their properties
what is an atomic theory?
the study of the nature of atoms and how they combine to form all types of matter
why is the atomic theory important?
- to help us understand why there are different types of atoms
- to explain how atoms combine to form matter
according to john dalton, what was all matter made of?
small, indivisible particles called atoms
according to john dalton, were all atoms of an element identical?
yes
what did john dalton discover about different elements?
different elements have different properties
john dalton found that atoms of different elements could combine in specific ways to form what?
new substance
what did john dalton’s atomic model look like?
“billiard ball model”
an atom is a solid, indivisible sphere
what did jj thomson experiment with?
electric currents in glass tubes
what was jj thomson able to produce?
streams of negative charged particles from nonradioactive atoms
what did jj thomson conclude
atoms must contain positive charges if they contain negative energy
what did jj thomson’s atomic model look like?
“plum pudding model”
an atom is a postive sphere with negative electrons scattered throughout it
what did ernest rutherford experiment with?
a gold foil barrier, with positively charged particles shot at it
what did ernest rutherford expect to see?
all particles passing through the foil
what actually happened in ernest rutherford’s experiment?
most particles went through the foil, but some deflected off
what did ernest rutherford conclude?
atoms are mostly empty; the nucleus is positive and contains most of the atom’s mass
what did ernest rutherford’s model look like?
“nuclear model”
- an atom is mostly empty space
- has a small positive nucleus, surrounded by negative electrons
what did niels bohr predict?
electrons surrounded the nucleus in specific energy levels
what were niels bohr’s energy levels called?
“shells”
each shell could only contain what?
a specific number of electrons
the maximum number of electrons that could exist in each of the first 3 shells is what?
2/8/8
electrons could jump between shells by what?
gaining or losing energy
what did niels bohr’s atomic model look like?
“planetary model”
electrons are in specific orbits
what did james chadwick discover?
the nucleus contains neutral particles (neutrons) and positively charged particles (protons)
james chadwick discovered that each neutron in an atom has about the same ___ but the neutron carries no ____?
- mass
- electrical charge
according to the the quantum mechanical model, electrons do NOT exist as what?
tiny points inside an atom
according to the the quantum mechanical model, electrons exist in what?
specific energy levels
electrons surround what, resembling a cloud?
the positively charged nucleus
what does today’s quantum mechanical model look like?
a cluster of particles
