Physics Paper 1: Atomic Structure Flashcards
What is the radius of an atom?
1 × 10 to the power of -10 m
What does the nucleus of an atom contain?
Protons (+) and neutrons (-)
What is the overall charge of the nucleus in an atom?
Positive charge
Where are electrons found in an atom?
In energy levels which are at different distances from the nucleus
What happens with energy levels in an atom?
Energy levels further away from the nucleus are at a higher energy than those closer to the nucleus
What happens when an atom absorbs electromagnetic radiation?
An electron can move from a lower energy level to a higher energy level
What happens if an atom emits electromagnetic radiation?
The electron returns to a lower energy level
What does the atomic number tell us about an atom?
The number of protons (and electrons)
What does the mass number tell us about an atom?
Number of protons + neutrons
Why do atoms have no overall charge?
Because the number of positive protons is equal to the number of negative electrons, so they cancel each other out so the atom is neutral overall
How do we find the amount of neutrons in an atom?
Subtract the atomic number from the mass number
What is an isotope?
Atoms of the same element with different numbers of neutrons
What is an ion?
An atom that has gained or lost one or more electron
What did the Ancient Greeks believe?
They believed everything is made of atoms and atoms are tiny spheres which can’t be divided
What was discovered in 1897?
Scientists discovered that atoms contain tiny negative particle (electrons), atoms are not tiny spheres that cannot be divided, they must have an internal structure
What is the plum pudding model?
An atom is a ball of positively charged particles with electrons embedded in it
Describe the alpha scattering experiment
1) first tool a piece of gold foil- gold is useful because it can be hammered out into thin foil
2)fired alpha particles at gold foil
3)most alpha particles passed straight through the gold foil without changing direction
4)some particles got deflected and went different directions and others completely bounced off it
What were the results of the alpha scattering experiment?
1)most went straight through-atoms are mostly empty space- plum pudding model was wrong
2)Some alpha particles deflected means centre of atom must have a positive charge that repelled alpha particles
3)because some bounced straight back this mean the mass of the atom must be concentrated in the centre (nucleus)
What did the scientists swap the plum pudding model with because of the alpha scattering experiment?
The nuclear model
What did Niels Bohr discover?
.electrons orbit the nucleus at specific distances
.called orbits energy levels
What did James Chadwick discover?
The nucleus also contains neutrons
What do some isotopes have?
An unstable nucleus
How do isotopes with an unstable nucleus become stable again?
The nucleus gives out radiation, this is called radioactive decay
True or false: radioactive decay is a random process?
True
