Topic 4 - Atomic Structure Flashcards
What is the plum pudding model of the atom and who found out about it
J J Thompson discovered the electrons that could be removed. He suggested that atoms where spheres of positive charge like a plum fruit.
how was the plum pudding model replaced?
In 1909 scientists in rutherford lab fired alpha particles at gold foil. Most of the particles went through the foil, some deflected and some went back. the plum model couldn’t explain this.
What is the nuclear model of the atom (where is mass, charge)
because some particles flew back they realized that most of mass was in the centre of the nucleus. nucleus had positive charge since it repelled positive alpha particle.
How did the nuclear model find out about empty space
because nearly all of alpha particles passed through, most of atom was empty space.
What is the structure of the current atom
tiny nucleus that makes up most of mass. contains protons (1+), neutrons (0). the rest of atom is empty space with negative electrons (-1), that go around the nucleus.
number of protons = number of electrons
what are isotopes
They are different forms of the same element
What is the atomic number
all atoms have a set number of protons. the number of protons is the atomic number.
what is the mass number
the mass number is the mass of the nucleus.
number of protons + number of neutrons = mass number
How are isotopes formed
they have the same number of protons (atomic number) but have a different number of neutrons (mass number).
What happens if the isotope is unstable (radioactive decay)
if unstable then it decays into other elements and gives out radiation. does by balancing number of protons and neutrons by getting rid of excess energy. called radioactive decay
what do radioactive substances spit out (one)
they spit out one or more types of ionising radiation from their nucleus.
what does nuclear equations show
it shows the radioactive decay
how is nuclear equation written
atom before decay -> atom after decay + radiation emitted
