Q: What is an isotope?
A: Atoms of the same element with the same number of protons but different numbers of neutrons, resulting in different mass numbers.
Q: Why do isotopes of the same element have similar chemical properties?
A: Because chemical behaviour depends on electron configuration and proton number, which are identical for isotopes of the same element.
Q: Why can isotopes have different physical properties?
A: Because they have different masses due to different numbers of neutrons, affecting properties such as density and diffusion rate.
Q: Why does 1 mole of Li-6 have a different mass than 1 mole of Li-7?
A: Because isotopes differ in neutron number, changing their atomic mass.
Q: What determines nuclear stability?
: The balance between:
Strong nuclear force (attractive between nucleons)
Electrostatic repulsion (between protons)
Q: Why are stable isotopes not radioactive?
A: Their strong nuclear force balances proton–proton repulsion, creating a stable nucleus.
Q: Why are unstable isotopes radioactive?
A: Because the attractive and repulsive nuclear forces are unbalanced, making the nucleus unstable.
Q: Why is there a limit to how large a nucleus can grow?
A: Electrostatic repulsion increases with proton number, eventually overpowering the strong nuclear force.
Q: What is radioactive decay?
A: A spontaneous process where an unstable nucleus emits particles or radiation to achieve stability.
Q: What is transmutation?
A: The transformation of one element into another due to radioactive decay.
Q: What happens in alpha decay?
A: The nucleus emits an alpha particle (²⁴He nucleus).
Mass number decreases by 4, atomic number decreases by 2.
: What occurs in beta-minus decay?
A neutron converts into a proton, emitting:
An electron
An antineutrino
Atomic number increases by 1.
What occurs in beta-plus decay?
A proton converts into a neutron, emitting:
A positron
A neutrino
Atomic number decreases by 1.
What occurs in gamma decay?
: An excited nucleus releases energy as a gamma photon without changing mass or atomic number.
What is half-life?
The time required for half of a radioactive sample to decay.
Why must medical isotopes have short half-lives?
o minimise radiation exposure while still allowing imaging.
Q: What is mass number?
A: Number of protons + neutrons.
Q: How do you calculate neutrons?
A: Neutrons = Mass number − Atomic number.
Q: What does ³⁷Cl mean?
: Chlorine isotope with mass number 37 (17 protons, 20 neutrons).
Q: Why is relative atomic mass usually not a whole number?
A: Because it is a weighted average of all naturally occurring isotopes.
Q: How do you calculate RAM?
RAM = Σ (isotope mass × fractional abundance)
Why are hydrogen isotopes unique?
They have special names and show large mass differences relative to proton number.
Q: What is protium?
A: ¹H — 1 proton, 0 neutrons — most abundant (~99.98%).
Q: What is deuterium?
A: ²H — 1 proton, 1 neutron — used in NMR and heavy water (D₂O).
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Week 2.1: The Atom31
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Week 2.0 Development of the models of the atom40
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Week 3.0 Electron shells and configurations28
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Elemental spectroscopy30
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Isotopes32
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Week 5: Periodic Trends25
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More periodic trends but this time it is actually periodic trends37
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Matter and properties32
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Separation Techniques36
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Mettalic bonding21
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Ionic Bonding26
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Naming chemical compunds31
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Common Chemical Reactions35
