Chemistry of Life

Matter

• The four elements common to all living organisims are oxygen(O), carbon(C), nitrogen(N) and hydrogen(H)
  • Make up 96% of living human body

• Chemicals in non-living world are in different proportions and some elements common to living beings are rare

• All elements and reactions between them obey the same chemical and physical laws, regardless of whether they’re part of the living or non-living world

Structure of the atom

• Atom is the smallest unit of matter that retains all the chemical properties of an element *example: a gold coin is just a large number of gold atoms moulded into the shape of a coin, with a small amount of other contaminating elements.
  • A gold atom gets its properties from the tiny subatomic particle its made of
• Atom is made of protons, neutrons and electrons
  • All atoms contain these three particles, apart from hydrogen which has no neutrons
• Attraction between electrons and protons hold atom together

• The number of protons determines the which element an atom is, the number of electrons decide which kind of reactions the atom will undergo

• Proton and neutrons do not have the same charge, but a similar mass (\(1.67*10^-24\) grams)

• Electrons repel each other which gives the perception of solidity.

Atomic Number, atomic mass, and isotopes

What is radioactivity? It pops up from Fukushima to Spiderman, so what does it mean for something to be radioactive?

• Radioactivity is a property of an atom.
  • Radioactive atoms have an unstable nuclei
  • Radioactive atoms release sub-atomic particles to become more stable, giving off energy-radiation- in the process
  • isotopes = different Versions of elements
    • Elements come in both radioactive and non-radioactive versions
    • Versions differ by the amount of neutrons they contain
  • Small quantatities of radioactive isotopes occur in nature
    • example: A small amount of carbon exists as carbon-14 in the atmosphere, amount of carbon-14 in fossils allows scientists to work out age

Items in room

• glass table
  • elements = Si, O
  • date of creation = 3000 BCE
    • era = quaternary, neolithic
    • region = Mesopotamia (North Syria)
• Pine cone
  • elements = C, H, O, N, P, S
  • date of creation = 290 ma
    • era = permian
  • kingdom = Plant
    • division = conifer
• sea shell (gastropod)
  • elements = Ca, C, O
  • date of creation = 545 ma
    • era = cambrian
  • kingdom = animal
    • phylum = Mollusc
    • class = gastropod
• Paper