Structure of Atoms Flashcards
when did Rutherford perform an experiment?
1911
why did Rutherford perform an experiment?
he wanted to find the nature of atoms and the arrangement of electrons and protons within the atom.
the thickness of the gold foil?
0.00 004 cm
the alpha particles were obtained from?
disintegration of polonium (Po)
Rutherford’s atomic model resembles?
solar system
conclusion of Rutherford?
Defects of Rutherford’s atomic model?
Any particle in a circular orbit undergoes acceleration. During acceleration, charged particles would radiate energy. Thus, the revolving electron would lose energy and finally fall into the nucleus. If this were so, the atom should be highly unstable.
an electron ______ energy when it moves from higher energy to lower energy level?
emits
an electron ______ energy when it moves from lower energy to higher energy level?
absorbs
when does an electron emit energy?
when it moves from higher to lower energy level
when does an electron absorb energy?
when it moves from lower to higher energy level
Name the sub-shells.
4
s= 2e-
p= 6e-
d=10e-
f= 14e-
how many electrons can d sub-shell hold?
10 electrons
how many electrons can f sub-shell hold?
14 electrons
how many electrons can p sub-shell hold?
6 electrons
how many electrons can s sub-shell hold?
2 electrons
what are shells?
According to Bohr’s atomic theory, the electron in an atom revolves around the nucleus in one of the circular paths called shells or orbits. Each shell has a fixed energy. So, each shell is also called an energy level. Each shell is described by an n value.
As the value of n increases the ___________________?
distance of an electron from the nucleus and the energy of the shell increases.
how can we know the arrangement of electrons in shells?
by using the 2n2 formula
2 (number of shell) raised to 2
2x3 2
2x9
18
so, the third shell can hold max. of 18 electrons.
the energy of an electron in an orbit is proportional _____________________?
to its distance from the nucleus.
electron present in an orbit ________ radiate energy.
does/ does not
does NOT
what are isotopes?
isotopes are atoms of the same element that have the same atomic number but different mass numbers because of the difference in neutrons.
how many isotopes of hydrogen?
3
H-1 protium
H-2 deuterium
H-3 tritium
how many neutrons are in deuterium?
1 neutron
how many neutrons are in protium?
0 neutron