AS level Physics unit 1 particle physics part a

shells and sub shells around the nucleus

protons and neutrons

negatively charged

positively

protons and neutrons

unit of charge equal to the electrical charge transferred by a steady current of 1 ampere in 1 second

electric charge carried by a proton or equivalently the value of the electric charge carried by an electron

1.60x10^-19

1

1.673x10^-27

+1

+1.60x10^-19

1

1.675x10^-19

0

0

1/1840

9.11x10^-31

element

mass number/nucleon number

atomic number (number of protons)

an atom with the same number of protons (atomic number) but a different number of neutrons (mass number)

nuclide

charge of a specific particle divided by its mass

1.60x10^19C/1.67x10^-27kg 

= 9.58x10^7Ckg^-1

• gravity 
• electromagnetic force 
• weak interaction 
• strong interaction

• the force acts between all particles in the universe and has an infinite range (however reduces in strength according to the inverse square law) . 
• at an atomic scale it has negligible influence , as it is the weakest fundamental force in the universe . 
• gravitation is mediated by the gravitation (mediation)

• this force acts between any charged particles . it can either be repulsive (same charge) or attractive (different charges) . 
• the electromagnetic force is responsible for keeping molecules together . 
• the electromagnetic force is mediated by virtual photons

• this force acts on all known fermions or rather all particles with a 1/2 integer spin (quarks , leptons and baryons but not bosons-elemental bosons and baryons)
• the weak interaction acts over a very short range (roughly an atto-meter 1X10^-18) . Over this range it is many times stronger than gravitation (roughly 10^33)
• the weak interaction is responsible for electromagnetic decay . the weak interaction is mediated by W and Z bosons (elemental particles)

• the force is observable in two areas . on the small scale the strong interaction is responsible holding quarks together in hadrons , on the larger scale it binds protons and neutrons together inside the atomic nucleolus (when talked about in terms of binding protons and neutrons together it is referred to as the strong nuclear force or the residual strong force)  
• the strong force binding quarks together is mediated by gluons , while the mediator responsible for binding protons and neutrons together is the pion or Pi meson