P1: Atomic Structure Flashcards
What is an Alpha particle? (Not atomic structure)
A helium nucleus
What is a beta particle? (Not atomic structure)
One fast-moving electron.
What is a gamma particle? (Not atomic structure)
A high energy electromagnetic wave.
What is the atomic structure of an alpha particle?
4
2
What is the atomic structure of a beta particle?
0
-1
What is the atomic structure of a gamma ray?
0
0
What is the name of the first ever model of the atom?
The plum pudding model.
Describe the structure of the plum pudding model.
A sphere of positive charge with negatively charged electrons scattered around the atom.
Why did the plum pudding model need to change?
Ernest Rutherford discovered the nucleus with his gold scattering experiment
What were the results of the gold scattering experiment?
Most of the alpha particles passed straight through the foil,
A small number were deflected by large angles as they passed through the foil,
A very small number came straight back off the foil.
What was the gold scattering experiment?
A beam of alpha particles was directed at a very thin gold leaf suspended in a vacuum to determine the movement of particles and to test the plum pudding model of the atom
What conclusion did Rutherford come to thanks to the gold scattering experiment?
-The atom is mostly empty space.
-Like charges repel.
-Discovery of the nucleus, the positive charge and mass are concentrated in a tiny volume in the atom.
What is the name of Ernest Rutherford’s model of the atom?
The nuclear model.
Why did the nuclear model of the atom have to change?
Niels Bohr discovered energy levels in the atom that the electrons orbited in.
What is the name of Niels Bohr’s atom model?
Bohr model
Why did the Bohr model of the atom have to change?
James Chadwick proved the existence of the neutron.
How did Chadwick prove the existence of the neutron?
Performed a version of Rutherford’s gold scattering experiment, using a sheet of beryllium and a paraffin block instead of gold foil.
What is the atomic number?
The number of protons
What is the mass number?
The number of protons and neutrons
What defines an element?
Its atomic number.
What are isotopes?
Forms of an element that have the same number of protons but different numbers of neutrons.
What is an ion?
A charged particle. An atom with a different number of electrons.
How can an atom’s nucleus be stable?
If it has a certain amount of neutrons for the amount of protons it has.
What is the ionising power of alpha radiation?
High
What is the ionising power of beta radiation?
Low
What is the ionising power of gamma radiation?
Very low.