Particles Flashcards
Why are the isotopes of an element virtually identical in their chemical reactions?
Because they have the same number of protons and same number of electrons
What are isotopes?
Elements which have the same number of protons but a different number of neutrons
What are A, X and Z symbols for in terms of the structure of an atom?
A= number of protons and neutrons (nucleons) X= chemical symbol Z= number of protons
What is the charge of a proton?
1.6 x 10^-19 C
Natural samples of elements are often what?
A mixture of isotopes
What happens in annihilation?
Two particles destroy each other
Mass is converted to energy in the form of 2 gamma ray photons
What is an electron’s antiparticle?
A positron
When does annihilation happen?
When a particle and its antiparticle meet
What are the properties of a particle and its antiparticle?
Same mass
Opposite charge
Spin in opposite directions
What is the isotope of hydrogen that has 1 neutron?
Deuterium
What is roughly the diameter of a nucleus of an atom?
10^-15 m
Why do nuclei with a Z number above 20 need more neutrons to be stable?
Between protons there is repulsion from the electromagnetic force
Between nucleons the strong nuclear force is holding them together
More nuclear force is needed to hold nucleons together without them repelling
What effect do uncharged neutrons have on chemical properties?
They make little difference to chemical properties
What are beta-plus particles?
Fast moving positrons emitted by unstable proton-rich nuclei
What is the equation for electron capture?
Proton + electron –» neutron + electron neutrino
What is the electron’s mass compared to protons and neutrons?
About 2000 times less than that of a proton or neutron.
What is the charge of an electron?
-1.6 x 10^-19 C
What is the equation for beta plus decay?
Proton –» neutron + positron+ electron neutrino
Which interaction is involved in electron capture?
The weak interaction
Which interaction is involved with beta plus decay?
The weak interaction
What is the baryon number of a proton?
1
What is the baryon number of an electron?
0
What is the baryon number of a neutron?
1
What is the baryon number of an electron neutrino?
0
What is the baryon number of a positron?
0
What is the lepton number of a proton?
0
What is the lepton number of an electron?
1