Atoms consist of a nucleus containing protons and neutrons, surrounded by electrons in shells. The number of particles in an atom can be calculated from its atomic number and mass number.
Which of these describes an alpha particle?
A positively-charged subatomic particle
A neutral subatomic particle
A negatively-charged subatomic particle
What did the Geiger-Marsden experiment show about the structure of the atom?
Atoms cannot be broken into smaller particles
Electrons are randomly spread around the atom
A small, positive nucleus is surrounded by electrons
What is the centre of the atom called?
Which particles are found in the nucleus?
Protons and neutrons
What is the relative charge of a neutron?
Which subatomic particle has the lowest mass?
What is the definition of atomic number?
The number of neutrons in the atom
The number of protons in the atom
The number or protons + the number of neutrons in the atom
An atom of potassium is written as . What is the mass number of this atom?
How many neutrons are in the atom ?
How does the size of the nucleus compare to the size of the atom?
The nucleus is very small compared to the atom
The nucleus is about half the size of the atom
The nucleus occupies almost all of the atom