Atomic Basics
What is the center of an atom called?
Nucleus
Which subatomic particle has a negative charge?
Electron
What particles are found in the nucleus?
Protons and neutrons
Who first proposed the idea that matter is made up of tiny, indivisible particles called atoms?
Democritus
What is the atomic number based on?
Which particle determines the element’s atomic number?
What is the charge of the nucleus?
Positive
Which scientist discovered the nucleus through the gold foil experiment?
Ernest Rutherford
Who discovered the electron?
Joseph John Thomson
What subatomic particle is neutral?
Neutron
Name an element with only one proton in its nucleus.
Hydrogen
Who developed the planetary model of the atom with electrons orbiting the nucleus?
Niels Bohr
What two subatomic particles contribute most to an atom’s mass?
Protons and neutrons
What subatomic particle is responsible for isotopes?
Neutrons
What causes radioactive decay in certain nuclei?
Isotopes
What was the key discovery made by J.J. Thomson?
Electron
What is the term for atoms of the same element with different numbers of neutrons?
Isotopes
How does an atom become positively charged?
It loses electron.
Who discovered nucleus?
Ernest Rutherford
Which modern atomic theory describes electrons as existing in a cloud rather than fixed orbits?
Quantum mechanical model