Chapter 6.4 - Nuclear and Particle Physics Flashcards Preview

Physics OCR A A2 > Chapter 6.4 - Nuclear and Particle Physics > Flashcards

Flashcards in Chapter 6.4 - Nuclear and Particle Physics Deck (49)
Loading flashcards...
1

Alpha particle scattering experiment and what it proved

A stream of alpha particles were emitted at a piece of gold foil.  Most of the particles went straight through, but some were reflected back.  This meant that matter must be mostly empty space with small, dense positively charged pockets (the nucleus)

2

fm

femtometer - 10-15m

3

Standard notation for an atom

AZX

Where

A is mass number

Z is proton number

4

Radius of a nucleus

R = r0A1/3

where

r0 is a constant

A is the mass number

5

Value of r0

1.4 fm

6

Strong nuclear force

The force that holds the nucleus together against the repulsion of the electrostatic repulsion

7

How the strong force varies with distance

Repulsive < 0.5 fm

Attractive enough to overcome electrostatic repulsion at < 3 fm

8

Hadron

Particles that feel the strong nuclear force (made of quarks)

9

What is the only stable hadron

Proton

10

Lepton

Fundamental particles that don't feel the strong force but do feel the weak nuclear force

11

Examples of hadrons (2)

proton, neutron

12

Examples of leptons (2)

Electron, neutrino

13

Antiparticle and its properties

Every particle has an antiparticle with the same properties, except it will have the opposite charge

14

Pair production

When energy is transformed into a particle and an antiparticle

15

How a gamma ray might create antimatter

A high energy photon can turn into a electron and a positron via pair production.  The energy of the photon (hf) is transformed into the mass of the two produced particles (leftover energy is put to their kinetic energy)

16

Annihilation

When a particle meets its antiparticle the mass of both is converted into energy in the form of two photons

17

Quark

The building block of hadrons

18

Quark composition of a proton

uud

19

Quark composition of a neutron

udd

20

up quark charge

+2/3

21

down quark charge

-1/3

22

strange quark charge

-1/3

23

β- decay

Occurs in a neutron rich atom.  Neutron decays to a proton, electron and antineutrino.  (d --> u)

24

β+ decay

Occurs in a proton rich atom.  Proton changes into a neutron and emits a positron and a neutrino,  (u-->d)

25

Radioactive decay

When a nucleus stabilises by releasing particles/energy in various forms

26

Properties of radioactive decay

It is spontaneous and random

27

What is meant by spontaneous and random

There is no way to know when a nucleus will decay.  It can't be predicted

28

Alpha radiation

A helium nucleus

29

β radiation

An electron

30

γ radiation

A gamma ray