Atomic Pioneer
Which ancient Greek philosopher first proposed the idea of the atom as an indivisible particle?
Democritus
In Thomson’s model, how did he describe the atom?
A positive “pudding” with electrons embedded in it.
Which subatomic particle is positively charged and found in the nucleus?
Proton
What does the atomic number of an element represent?
The number of protons in the nucleus.
Where can electrons exist within an atom?
In fixed distances called energy levels.
Whose atomic theory stated that all matter is made up of tiny, indivisible atoms?
John Dalton
The analogy of chocolate chip ice cream is used to describe which model?
Thomson's Model
Which subatomic particle has no electrical charge?
Neutron
What is the nucleus of an atom?
The dense center containing protons and neutrons.
What does the electron cloud represent?
The area where electrons are likely to be found.
What was J.J. Thomson’s key contribution to atomic theory?
He discovered subatomic particles (electrons).
What was the major conclusion from Rutherford’s gold foil experiment?
Atoms are mostly empty space.
What is the role of electrons in an atom?
They orbit the nucleus and play a key role in bonding.
How is the mass number of an atom determined?
By adding protons and neutrons.
What is an orbital?
A region around the nucleus where electrons are likely to be found.
Whose gold foil experiment led to the discovery of the atomic nucleus?
Rutherford
Which statement best describes the relationship between Dalton’s atomic theory and modern atomic theory?
Modern theory builds upon and revises Dalton’s ideas.
Why is the neutron considered important in the nucleus?
It prevents protons from repelling and adds to atomic mass.
What is an isotope?
An atom of the same element with a different number of neutrons.
What is electron configuration?
The arrangement of electrons among orbitals and energy levels.
How did Rutherford’s findings about the nucleus change our understanding of the atom?
He concluded the nucleus is dense and contains most of the atom’s positive charge.
In Bohr’s model, where are electrons located?
In fixed energy levels around the nucleus.
What does the term “subatomic particles” refer to?
Particles that make up atoms — protons, neutrons, and electrons.
Circle the correct expression: Mass of 1 Neutron = Mass of 1 _______.
Proton
When all electrons are in the lowest possible energy levels, what is the atom’s state?
Ground state (most stable configuration).