Early Atomic Theories
Which Greek philosopher first proposed the idea of an indivisible atom?
Democritius
Rutherford concluded the nucleus is dense and contains most of the atom’s what?
positive charge
Which subatomic particle has a positive charge?
proton
The atomic number represents the number of what?
protons
What is the role of electrons in an atom?
They orbit the nucleus and play a key role in bonding
What was J.J. Thomson’s major contribution to atomic theory?
He identified subatomic particles
The mass number equals the sum of which two subatomic particles?
Protons + neutrons
Which subatomic particle has no charge?
neutron
How is mass number determined?
Protons + neutrons
Where can electrons exist within an atom?
In fixed distances called energy levels
The chocolate chip ice cream model represents which atomic model?
Thomson's Model
Which model describes electrons embedded in positively charged “pudding”?
Thomson’s model
Why is the neutron crucial to the nucleus?
It acts as a buffer to prevent protons from repelling each other
What is an isotope?
A variant of an element with different numbers of neutrons
What does the electron cloud represent?
The area where electrons are likely to be found
Rutherford’s gold foil experiment revealed that atoms are mostly what?
empty space
What is the nucleus of an atom?
The central part containing protons and neutrons
Compare the masses accurately:
A) Mass neutron = mass proton
Mass of 1 neutron ≈ mass of 1 proton
Isotopes have the same number of ________ but different numbers of ________.
Protons; neutrons
What is an orbital?
A region around the nucleus where electrons are likely to be found
Which statement best describes how Dalton’s theory relates to modern atomic theory?
Modern atomic theory has built upon and revised Dalton’s ideas based on new evidence
Based on Rutherford’s experiments, what conclusion was drawn about positive charge in atoms?
It varies among elements
Name the three subatomic particles.
proton, neutron, electron
Which statement best describes isotopes?
Atoms of the same element with different mass numbers due to varying neutron counts
What is electron configuration?
The distribution of electrons among orbitals and energy levels