7A.1 Nuclear Atom

Question 1

what is the history of an atom

Answer 1

1. in 400 BCE Democritus was the first to suggest the existence of an atom where he said an atom is a tiny particle from which everything is constructed from
2. in 1803 Dalton found out that different atoms have different masses and can be combined to produces compound molecules and he called them hard solid spheres
3. in 1906 J.J Thomson’s plum pounding model of the atom, where he found out that removing the negative charge in an atom produces a positive ion, from that he conclude that electrons are imbedded in a cloud of positive ‘dough’
   3.1911 where Ruthford experiment with shooting dense positively charged alpha particles into a thin gold foil to be surprised that they were reflected back, where he concluded that a large amount of positive charge and most of the mass is concentrated in a tiny central nucleus. most of the atom is empty space, and electrons orbit at the edge
4. 1913 where neils bohr’s suggested that the electrons are limited to a certain fixed energy orbitals, which the can jump between by gaining or losing energy
5. in the 1920s Heisenberg changed the atom model where using his uncertainty principle which states that we can know the exact position or velocity of an electron in a given moment so instead of the electrons orbiting around in specific orbits they orbit in something called “probability clouds”

Question 2

what was the conclusion that Rutherford made when most alpha particles passed through with little deviation

Answer 2

most of the atom is empty space

Question 3

what was the conclusion that Rutherford made when some alpha particles deflected at a large angle

Answer 3

a large concentration of charge is at one place

Question 4

what was the conclusion that Rutherford made when few alpha particles were deflected back to the source or to the side of the foil

Answer 4

most of the mass of the atom, and a large concentration of the charge is in a tiny central nucleus

Question 5

what can we take from the James Chadwick’s experiment to prove the neutron

Answer 5

that conservation of momentum can apply to particles

Question 6

what did Rutherford suggest for the extra mass in the nucleus

Answer 6

he suggested that there were proton-electrons pairs in the nucleus

Question 7

what triggered the discovery of the neutron

Answer 7

it was triggered by Joliot-curies and her husbands experiment where the tried to explain the unknown radiation that is formed when shooting alpha particles to a beryllium atom as gamma radiation but it doesn’t have any mass so teh conservation of momentum didn’t applied, which made James Chadwick repeat the experiment taking momentum and energy as a factor to find the neutron

Question 8

what is the mass of a neutron compared to a proton

Answer 8

1% more than a proton

Question 9

what is a nucleons

Answer 9

any of the protons or neutrons comprising a nucleus

Question 10

what is a proton number/ atomic number

Answer 10

number of protons in the nucleus

Question 11

what are isotopes

Answer 11

atoms of the same element but with different number of neutrons

Question 12

what is the strong nuclear force

Answer 12

the extremely short-range force between the hadrons (such as protons and neutrons

Question 13

what is the importance of neutrons

Answer 13

they help[ bind the nucleus together as they exert a strong nuclear force on the rest of the nucleons, and they act as space between the positively charged protons which repeal each other

Question 14

what is the nucleon/mass number

Answer 14

the number of protons plus neutrons in a atom

Question 14

what is the neutron number

Answer 14

the total number of neutrons in a nucleus