Radioactivity- Atoms Flashcards
What is the first model of the atom and who discovered it?
Plum pudding model discovered by JJ Thompson in 1897.
Positive _______ (protons and neutrons) surrounded by negative _________ in ______, discovered by __________.
Positive nucleus (protons and neutrons) surrounded by negative electrons in shells, discovered by Rutherford.
How did Rutherford disprove the plum pudding model?
Rutherford disproved plum pudding model by firing alpha particles at gold foil. The
wide scattering pattern suggested the nucleus.
Electrons can jump to a ______ energy level (further from the _______) with
absorption of ______________ radiation.
Electrons can jump to a higher energy level (further from the nucleus) with
absorption of electromagnetic radiation.
Describe what the plum pudding model was like
A mass of positive charge with negative charged electrons dotted about.
what is the radius of an atom
1x10^-10 m
what is the central region of the atom called and what is the size of it
the nucleus
1/10000 of the radius of the atom
what are the two sub atomic particles found in the nucleus and what are the charges on these
how does this effect the overall charge of the atom
neutrons (neutral) and
protons (positive charge)
leaving the nucleus with an overall positive charge
what surrounds the nucleus
what’s the charge
electrons negative charge
energy levels which are _______ from the nucleus are at a ______ energy than those which are closer to the nucleus
energy levels which are further from the nucleus are at a higher energy than those which are closer to the nucleus
for every element on the periodic table, there are two numbers.
what is the smaller number and what does it tell you
atomic number
number of protons and electrons in the element
why do atoms have no overall charge
neutrons have no charge to begin with, and although protons have a positive charge, and electrons have a negative charge then number is always the same meaning the charges cancel each other out
for every element on the periodic table, there are two numbers.
what is the larger number and what does it tell you
mass number
number or protons and neutrons
what are isotopes
atoms of the same element with a different number of neutrons
what happens if an atom looses or gains an electron
it becomes a positive or negative ion
what was discovered in 1897
why was this important
electrons
shows that atoms must have an internal structure
during the alpha scattering experiment, why was gold foil used
it can be hammered out into just a few atoms thick
what particles were fired at the gold foil
what’s the charge
alpha particles
positive
what did scientists conclude from the alpha scattering experiment
straight through - atom is mostly empty space
deflected - centre of the atom has a positive charge
bounced back - mass is dfoung in the center
why did the alpha particles bounce back off the nucleus
because the alpha particle and nucleus both have a positive charge
what did Niels Bohr propose
electrons orbit the nucleus
who discovered neutrons and when
James Chadwick
20 years after the nuclear model was first proposed
