Structure of water and hydrogen bonding

• Isotopes


  Atoms of one element that vary only in the number of neutrons that they have
• Half-life


  Rate of decay of a radioactive element
• All isotopes of the same element are chemically identical
• All isotopes of the same element are chemically identical because they have the same electron configuration, which makes them interact with other elements in the same way
• Chemically identical


  What you call two elements that react with the other elements around them in the exact same ways
• Radioisotopes


  Isotopes of an element that are radioactive
• Radioactive iodine ( I-131 )


  Is used to diagnose and treat certain diseases in the thyroid gland
• Tracer


  Radioisotope (such as CO2) that is incorporated into a molecule to follow the path of CO2 in a metabolic pathway
• Electron configuration


  What determines how an element interacts with other atoms around it
• Ground state


  When all the electrons in an atom are at their lowest available energy levels
• Electronegativity


  The ability of an atom to attract electrons
• Ionic bond


  When an electron is transferred between two atoms, giving one a positive charge, and the other a negative charge. The attraction of these charged ions creates this bond
• Covalent bond


  When two atoms share electrons because they have similar electronegativity
• Nonpolar covalent bond


  When the electronegativity of two atoms are identical, so they perfectly equally share atoms (O2)
• Polar covalent bond


  When electrons are shared unequally between two atoms, leaving one with a partial positive charge and one with a partial negative charge
• Diatomic molecule


  Molecules made up of only two atoms
• Diatomic


  Type of molecules usually involved in nonpolar covalent bonds
• Hydrogen bonds


  Weak bonds between molecules
• Hydrogen bond


  When a positively charged hydrogen is attracted to a negatively charged area on another molecule (ie the hydrogens of water attaching themselves to the oxygens of other water molecules)
• Hydrogen bond

  
• Covalent bond

  
• Ionic bond

  
• Water is a polar covalently bonded molecule, meaning it has a positive and negative end
• Water is a great solvent because it is polar, which means its opposite charges interact with and break up ionic or polar covalent bonds when put into the water
• Hydrophilic


  Substances that dissolve in water
• Hydrophobic


  Substances that do not mix with or dissolve in water
• All the electron pairs in a water molecule--shared or unshared--repel each other, leading to all electron pairs being as faraway from each other as possible, creating a bent shape

  
• Oxygen in water has a partially negative charge
• Hydrogen in water has a partially positive charge
• Heat capacity


  Degree to which a substance changes temperature based on changes in heat
• Cohesion


  Attraction of molecules to other molecules of the same kind
• Water has strong cohesive forces because of its molecules' ability to hydrogen bond together
• Surface tension


  Phenomenon where a liquid's surface resists rupture when put under tension or stress
• Surface tension with water happens because when a molecule is on the surface, only some of its neighbours are water; the rest are air. This makes the surface molecules form stronger bonds with the water molecules it is near
• Adhesion


  Attraction of molecules to molecules of a different kind
• Capillary action


  When a liquid moves up a thin tube against gravity because of cohesion and adhesion
• Meniscus


  Curved surface of water in a tube or cylinder
• Water meniscus

  
• Capillary action depends on the adhesion of the water molecules to the glass tube, as well as cohesion between the water molecules
• Water is more strongly attracted to the glass than other water molecules because it is even more polar, which causes it to creep up the sides of glass tubes, forming a meniscus