gcse aqa history of a atom Flashcards
What is the basic unit of matter?
Atom
Who proposed the first atomic theory in 1803?
John Dalton
True or False: Atoms can be created or destroyed in chemical reactions.
False
What did J.J. Thomson discover in 1897?
The electron
Fill in the blank: The nucleus of an atom contains _____ and _____.
protons, neutrons
What model of the atom did Ernest Rutherford propose?
The nuclear model
Who developed the planetary model of the atom?
Niels Bohr
What is the charge of a proton?
Positive
What is the charge of an electron?
Negative
True or False: Neutrons have a positive charge.
False
What is the term for the number of protons in the nucleus of an atom?
Atomic number
Which scientist is known for the quantum mechanical model of the atom?
Erwin Schrödinger
What is the mass of a neutron compared to a proton?
Approximately equal
What is an isotope?
Atoms of the same element with different numbers of neutrons
Fill in the blank: The _____ model describes electrons as existing in probability clouds.
quantum mechanical
What did the Gold Foil Experiment demonstrate?
The existence of a small, dense nucleus
Who introduced the concept of quantized energy levels?
Niels Bohr
What is the main limitation of the Rutherford model?
It could not explain the stability of the atom.
True or False: Electrons are found in fixed orbits around the nucleus.
False
What is the maximum number of electrons in the first energy level?
2
What is the role of neutrons in the nucleus?
To provide stability
Who is known for the discovery of the neutron in 1932?
James Chadwick
What does the term ‘valence electrons’ refer to?
Electrons in the outermost shell
True or False: The atomic mass of an element is the weighted average of all its isotopes.
True
What is the significance of the periodic table in relation to atoms?
It organizes elements by atomic number and properties.
Fill in the blank: The _____ is the smallest particle of an element that retains its chemical properties.
atom
What are the three main subatomic particles?
Protons, neutrons, electrons
What did the Cathode Ray Experiment lead to the discovery of?
Electrons
What is the significance of the atomic number in identifying an element?
It determines the element’s identity.
Who proposed the Plum Pudding Model?
J.J. Thomson
True or False: The nucleus is positively charged.
True
What is the primary difference between the Bohr model and the quantum mechanical model?
The Bohr model has fixed orbits; the quantum model describes probability clouds.
What does the term ‘ion’ refer to?
An atom with a net electric charge due to loss or gain of electrons.
Fill in the blank: The _____ number represents the total number of protons and neutrons in an atom.
mass
What did the discovery of the neutron help explain?
The stability of the nucleus.
What is the term for the energy required to remove an electron from an atom?
Ionization energy
Who first proposed the idea that matter is made up of indivisible particles?
Democritus
True or False: All atoms of the same element have the same number of protons.
True
What is a cation?
A positively charged ion
What is an anion?
A negatively charged ion
Fill in the blank: The _____ model was replaced by the quantum mechanical model.
Bohr
What does the term ‘electron configuration’ refer to?
The distribution of electrons in an atom’s energy levels.
