radiation and radioactivity

what does wave particle duality mean and what are the 2 processes that act this way

• wavelengths act like both wave and particles (shared similarities)

• refraction - change of medium , reflection

Different processes in radiation

• refraction - change of medium

• Interference - add waves

• Destructive - neutralises

• Diffraction - spreads out

• Polarisation - only way travels through axis

• Photoelectric effect - photon energy fighting electrons, emitting electricity

• Reflection

What does natural vs man made mean and ionising vs non ionising in radiation

• natural - naturally occurring radiation such as cosmic background radiation, Cornwall - radon deposits

• Man made - manufacturing things like x ray tubes

• Ionising = dangerous and can alter atoms and cell biology

• Non = not as dangerous

What does radioactivity mean , measure and process

• emission of radiation in a spontaneous way

• Occurs from decay of unstable atoms where the atomic structure changes

• measure = becquerels (Bq) - measuring the number of decays per second

Whats the atomic number + atomic mass

• atomic number = z = number of protons

• Atomic mass = number of protons and neutrons = A

• Atomic mass is generally higher than the atomic number

Why do the shells of an atom affect the reactivity

• either wants to be full or empty and share with another atom

• Outer shells are more reactive

Whats binding and potential energy

• binding = force of attraction , electrostatic force between nucleus and electrons

• Electrons pulled towards the nucleus have stronger binding energy

• Low binding energy = high potential energy

• Electrons beyond the reach of the nucleus have maximum potential energy and zero binding energy (can do anything)

• Potential = energy electrons have themselves to stay in its orbital shell

What happens when an atom has an empty space in the inner shell

• outer shell drops down , BE changes

• Energy is emitted into radiation

• Outer shell is then empty but stable and a negative shell is lost = now a positive ion

What are the 2 atomic variants

• isotopes = different number of neutrons , same atomic number (protons) and different atomic mass

• Nucleides = nucleus is excited and same atomic number and ass , by product of radioactive decay = change of proton and neutron number and more energy in the nucleus so has to emit to become stable

• Unstable variants will decay

Types of radioactive decay

• change in structure and energy to make atom stable

• Alpha = nuclear instability - too big , biggest emissions, 2 protons and 2 neutrons are emittted = change in atomic number and mass

• Alpha = Z is -2 and A is -4

• beta negative = too much neutrons and protons - neutron will split and emit an electron - atom needs to be stable so neutron will convert but same mass, neutron has no charge and proton does - needs to emit negative charge aka electron

• Beta negative = z is +1 and a is 0 = anti neutrino = extra energy emitted as one

• Beta positive has too many proteins and converts to neutron but stays in nucleus - needs to lose positive charge so emits a positron. When too much energy is left = emits extra energy aka neutrino. Z = -1 (loss of neutron) and a = 0 (no change).

• Gamma = any additional energy emitted as gamma ray - no change or loss , just emissions - only change in energy.

What does decay chain mean

• some atoms start off with too many protons / neutrons