# Shared Flashcard Set

## Details

OCR A
The structure of the nucleus
17
Physics
05/22/2008

Term
 What nucleons make up the nucleus of an atom?
Definition
 Protons and neutrons
Term
 How would you represent the nucleus of an atom?
Definition
 Mass number (number of nucleons) on top and atomic number (number of protons) on the bottom with the element next to it      4 He2(not that great but you know what i mean)
Term
 What equation can be used to work out the number of neutrons in an atom?
Definition
 Neutrons = neucleons - protons(N = A - Z)
Term
 Three types of nuclear reaction?
Definition
 Radioactive decay, nuclear fission and nuclear fusion
Term
Definition
 Unstable nucleus of an atom spontaneously changing into something different, emitting radiation as it does so.
Term
 Explain nuclear fission
Definition
 When a large nucleus splits into two smaller nuclei. Ccan be spontaneous or induced by bombarding with neutrons.
Term
 Explain nuclear fusion
Definition
 When two smaller nuclei join (fuse) to make one large nucleus. Can only occur when they have high energies (under high temperature)
Term
 What force keeps the nucleons in the nucleus, even though the Coulomb force of attraction is pulling them apart and Gravitational force is too weak?
Definition
 The Strong Force (hell yeah)
Term
 How can we find the radius of a nucleus?
Definition
 Radius of nucleus = radius of one nucleon x number of nucleons to the power of 1/3r = r0A1/3
Term
 How can we find the density of a nucleus?
Definition
 Density = mass               volumeSo density of nucleus = mass4/3∏r3(yes that funny symbol IS pi)
Term
 How can we measure electrostatic (Coulomb) force?
Definition
 F =     1     Q1Q2       4∏ε0     r2 ε0 = 8.85x10-12 Fm-1
Term
 How can we measure gravitational force?
Definition
 F = G m1m2           r2 G = 6.673x10-11 Nm2kg-2
Term
 What properties does the strong force have? (Thinking about the graph of distance between nucleon centres against strong force)
Definition
 Short range forceActs between nucleons close togetherIf nucleons overlap, becomes a repulsive force rather than an attractive force
Term
 What is binding energy?
Definition
 The difference between the potential energy of an atomic nucleus and the total potential energy of all its nucleons if they were seperate.Typically, potential energy of an atomic nucleus is lower than the potential energies of the seperate nucleons
Term
 How can binding energy be a measure of stability?
Definition
 The greater the binding energy per nucleon, the more stable the nucleus is
Term
 Which formula relates mass and energy and how does this affect nucleons?
Definition
 ΔE = Δmc2c = 2.998x108 ms-1This means that the nucleons inside a nucleus have less mass than if they were seperate nucleons
Term
 So why does nuclear decay occur?
Definition
 The nuclei want to become more stableLarge nuclei have high binding energy, so split into smaller, more stable nuclei (nuclear fission)Small nuclei have low binding energy, so join together to a larger, more stable nucleus (nuclear fusion)Therefore the most stable nuclei are those of intermediate size (iron being the more stable of all)
Supporting users have an ad free experience!