Revision Checklist for P4 Structure of the Atom Flashcards
(40 cards)
What is the radius of an atom?
Approximately 1 × 10^-10 metres.
What is the size of the nucleus compared to the atom?
The nucleus is 1/10,000 smaller, about 1 × 10^-14 metres across.
Where is most of the mass of an atom concentrated?
In the nucleus.
How are electrons arranged in an atom?
At different distances from the nucleus at different energy levels.
What happens to electron arrangements when electromagnetic radiation is absorbed?
Electrons move further from the nucleus to a higher energy level.
What happens to electron arrangements when electromagnetic radiation is emitted?
Electrons move closer to the nucleus to a lower energy level.
What is the definition of atomic number?
The number of protons in an atom.
What is the mass number?
The total number of protons and neutrons in an atom.
In a neutral atom, how do the number of electrons compare to the number of protons?
They are equal.
How do you calculate the number of neutrons in an atom?
Mass number - atomic number.
What is an isotope?
Atoms of the same element with different numbers of neutrons.
How are ions produced?
By gaining or losing electrons.
What is the plum pudding model?
A model proposed by JJ Thomson describing atoms as a positive ‘pudding’ with negative electrons embedded.
What were the main observations from the Rutherford alpha scattering experiment?
- Most alpha particles passed through 2. Some deflected at large angles 3. A few bounced back.
What is Rutherford’s initial nuclear model?
A model proposing that atoms have a dense nucleus surrounded by electrons.
What does Bohr’s model of the atom describe?
Electrons orbiting the nucleus at fixed energy levels.
What is the significance of Chadwick’s discovery of the neutron?
It explained the missing mass in atomic nuclei and led to a better understanding of atomic structure.
Define radioactive.
The process by which unstable atomic nuclei lose energy by emitting radiation.
What is activity in the context of nuclear physics?
The rate at which a sample of radioactive material decays.
What is the count rate?
The number of decays detected per unit time.
What unit is used to measure radioactive decay?
The Becquerel (Bq).
Identify the properties of alpha particles.
- Relative mass: 4 * Relative charge: +2 * Range in air: a few cm * Penetrability: low * Ionising power: high.
Identify the properties of beta particles.
- Relative mass: 1/2000 * Relative charge: -1 * Range in air: several meters * Penetrability: moderate * Ionising power: moderate.
Identify the properties of gamma rays.
- Relative mass: 0 * Relative charge: 0 * Range in air: unlimited * Penetrability: high * Ionising power: low.
