Chemistry

• Chemistry


  Complex system that we cannot see which we try understand through models. Understanding how the system changes.
• Common elements in the body


  • Oxygen (water)
  • Carbon (organic compounds)
  • Hydrogen (water)
  • Nitrogen (protein, nucleic acids)
  • Calcium (bones, muscles)
  • Phosphorus (ATP)
  • Potassium (electrolytes - nerve signalling)
  • Sodium/Chlorine
• Organic compounds


  Those which do not contain metallic elements. In the body - carbohydrates, fats, proteins, nucleic acid.
• States of matter


  • Solid - rigid, fixed volume and shape
  • Liquid - flowing, takes shape of container, defined volume
  • Gas - no fixed shape or volume, takes shape and volume of container, lots of energy
• Physical change


  Usually reversible, no rearrangement of atoms just interactions, can be measured or observed, no new substances.
• Chemical change


  Usually irreversible, rearrangement of atoms of one or more substances, change in chemical properties or composition, all resulting in formation of at least one new substance.
• Elements


  Simplest substances cannot be broken from chemical reactions.
• Structure of an atom


  • Smallest particle of chemical element that can exist, built by 3 subatomic particles: 1. Protons, 2. Neutrons make up nucleus, 3. Electrons - shells 1st = 2, 2nd = 8 , 3rd=18, 4th=32.
• Mass number


  Approximate number of protons and neutrons in an atom.
• Isotopes


  Equal number of protons but different number of neutrons in nuclei.
• Atom


  Neutral, contain same number of protons as electrons.
• Ion


  Electrically charged, removing or giving electrons to give +ve or -ve ion.
• Molecule


  When two or more atoms join together.
• Compound


  Mole with at least 2 different atoms which are chemically bonded.
• Sucrose


  • In common table sugar, disaccharide, composed of two monosaccharides - glucose and fructose, molecular formula - C12H22O11, melting point - 186oC, soluble in water
• Glucose


  • Molecular formula - C6H12O6, energy source, most carbohydrates you eat are converted to glucose, function - energy or stored in muscle cells or liver as glycogen for later use.
• Gluten


  • Important in baking, formed by two proteins, gliadin - C29H41N7O9, glutenin - much bigger.
• Electrons


  The driving force behind chemistry
• Electrons move


  So they can be stable, having a full valance electron configuration
• Periodic trends - electronegativity


  • Strength of atom to attract electrons driven by the sheilding of the positive nucleus
  • Across (getting more electronegative)
  • Down (getting less electronegative)
  • Metals are on left, nonmetals are on right
• Compound


  Molecule with at least 2 different atoms which get chemically bonded
• Atoms


  Both trying to get stable from valence shell
• Ionic bonds


  When two atoms with different electronegativity, transfer between atoms, results in cation (+ve ion), and nonmetal (-ve ion), ions formed together with electrostatic attraction, losing or gaining a electron, no defined shape, high melting, boiling point
• Covalent bonds


  Similar electronegativity, share their electrons in outer molecular orbit, formed between non-metals, low melting, boiling point
• Electrons


  Share between atoms
• Molecule


  Atoms chemically bound together, can be single element (eg O2), electrically neutral group, non polar, polar molecules
• Polar


  Atoms different electro-negativity bound together, different atoms, bonding electrons close to one atom
• Non-polar


  Atoms similar electronegativity bound together, identical atoms, electrons found halfway
• Molecules with same/similar polarities mix together
• Hydrogen bonds


  Bond between another atom NOF, partically electrostatic force of attraction, hydrogen act as proton donor, bonds another atom with lone pair, can occur in inorganic and organic molecules
• Molecular mass (molecular weight)


  Sum of atomic masses of element in compound, small and medium molecules mass measured by mass spectrometry
• Moles


  Used as expression of concentration
• Mole equation
• what is what

  A) Freezing

  B) melting

  C) Sublimation

  D) deposition

  E) evaporation

  F) condensation