P4 - Atomoic Structure Flashcards
Who first proposed the idea that matter is made up of tiny spheres called ‘atomos’?
Democritus
What did John Dalton contribute to atomic theory in 1804?
Matter is made up of tiny spheres (‘atoms’) that couldn’t be broken up, and each element is made up of a different type of atom.
Who discovered electrons and proposed the plum pudding model?
J.J. Thomson
What was the prediction of the plum pudding model regarding alpha particles passing through gold foil?
Most alpha particles would pass straight through or be slightly deflected.
What was the outcome of the alpha scattering experiment conducted in Rutherford’s lab?
Some alpha particles were deflected back, indicating a concentrated mass in the center of the atom.
What does the nuclear model of the atom consist of?
A positively charged nucleus surrounded by a cloud of negative electrons.
Who proposed that electrons orbit the nucleus at certain distances called energy levels?
Niels Bohr
What particles make up the nucleus according to the current model of the atom?
Protons and neutrons
What is the relative charge of a proton?
+1
What is the relative charge of a neutron?
0
What is the relative charge of an electron?
-1
How does the size of the nucleus compare to the size of the atom?
The nucleus is about 10,000 times smaller than the radius of the atom.
What happens to electrons when they gain energy from absorbing EM radiation?
They move to a higher energy level, further from the nucleus.
What occurs when an outer electron leaves the atom?
The atom becomes a positively charged ion.
True or False: The current model of the atom is unlikely to change in the future.
False
Fill in the blank: The current model of the atom includes a nucleus that contains ______ and ______.
protons, neutrons
What was the significance of James Chadwick’s discovery in 1932?
It proved the existence of the neutron, explaining the imbalance between atomic and mass numbers.
What gives the atom its overall size?
Negative electrons whizzing around the outside of the nucleus.
What are isotopes?
Isotopes are atoms with the same number of protons but a different number of neutrons.
What determines the atomic number of an element?
The atomic number is determined by the number of protons in an atom.
How is the mass number of an atom calculated?
The mass number is the number of protons plus the number of neutrons.
What is the relationship between isotopes and atomic number?
Isotopes have the same atomic number but different mass numbers.
What is radioactive decay?
Radioactive decay is the process by which unstable nuclei lose energy by emitting radiation.
What types of ionising radiation are commonly known?
- Alpha radiation
- Beta radiation
- Gamma radiation