molecule

Examples of molecule in the following topics:

• Homonuclear Diatomic Molecules

  • Diatomic molecules are composed of only two atoms, of either the same or different chemical elements.
  • Common diatomic molecules include hydrogen (H2), nitrogen (N2), oxygen (O2), and carbon monoxide (CO).
  • All diatomic molecules are linear, which is the simplest spatial arrangement of atoms.
  • Translational energies (the molecule moving from point A to point B)
  • A space-filling model of the homonuclear diatomic molecule nitrogen.

• Molecules

  • Most often, the term "molecules" refers to multiple atoms; a molecule may be composed of a single chemical element, as with oxygen (O2), or of multiple elements, such as water (H2O).
  • Most molecules are too small to be seen with the naked eye.
  • The full elemental composition of a molecule can be precisely represented by its molecular formula, which indicates the exact number of atoms that are in the molecule.
  • Isomers are molecules with the same atoms in different geometric arrangements.
  • Each molecule is a structural isomer of the other.

• Polyatomic Molecules

  • A polyatomic molecule is a single entity composed of at least three covalently-bonded atoms.
  • Molecules are distinguished from ions by their lack of electrical charge.
  • The science of molecules is called molecular chemistry or molecular physics, depending on the focus.
  • A pure substance is composed of molecules with the same average geometrical structure.
  • Molecules with the same atoms in different arrangements are called isomers.

• Dipole-Dipole Force

  • Molecules that contain dipoles are called polar molecules and are very abundant in nature.
  • A dipole is a molecule that has split charge.
  • The negatively charged oxygen atom of one molecule attracts the positively charged hydrogen of another molecule.
  • Attractions between polar molecules vary.
  • Choose a pair of molecules from the drop-down menu and "pull" on the star to separate the molecules.

• Introduction to Intermolecular Forces

  • Our chief focus up to this point has been to discover and describe the ways in which atoms bond together to form molecules.
  • Since all observable samples of compounds and mixtures contain a very large number of molecules (ca. !
  • 020), we must also concern ourselves with interactions between molecules, as well as with their individual structures.
  • All atoms and molecules have a weak attraction for one another, known as van der Waals attraction.
  • This attractive force has its origin in the electrostatic attraction of the electrons of one molecule or atom for the nuclei of another.

• Ion-Dipole Force

  • The ion-dipole force is an intermolecular attraction between an ion and a polar molecule.
  • However, ion-dipole forces involve ions instead of solely polar molecules.
  • An ion-induced dipole force occurs when an ion interacts with a non-polar molecule.
  • Ion-dipole forces are generated between polar water molecules and a sodium ion.
  • The oxygen atom in the water molecule has a slight negative charge and is attracted to the positive sodium ion.

• Dipole Moment

  • A dipole exists when a molecule has areas of asymmetrical positive and negative charge.
  • At one extreme, a symmetrical molecule such as chlorine, Cl2, has 0 dipole moment.
  • Symmetry is another factor in determining if a molecule has a dipole moment.
  • As a result, carbon dioxide is a nonpolar molecule.
  • When a molecule consists of more than two atoms, more than one bond is holding the molecule together.

• Condensation Reactions

  • Condensation is a chemical reaction in which one molecule is formed and one small molecule (often water) is lost.
  • In a condensation reaction, two molecules or parts thereof combine, releasing a small molecule.
  • When this small molecule is water, it is known as a dehydration reaction.
  • When two separate molecules react, their condensation is termed intermolecular.
  • An example is the Dieckmann condensation, in which the two ester groups of a single diester molecule react with each other to lose a small alcohol molecule and form a β-ketoester product.

• Boiling & Melting Points

  • As temperature is increased, there is a corresponding increase in the vigor of translational and rotation motions of all molecules, as well as the vibrations of atoms and groups of atoms within molecules.
  • Large molecules have more electrons and nuclei that create van der Waals attractive forces, so their compounds usually have higher boiling points than similar compounds made up of smaller molecules.
  • The upper row consists of roughly spherical molecules, whereas the isomers in the lower row have cylindrical or linear shaped molecules.
  • The distance between molecules in a crystal lattice is small and regular, with intermolecular forces serving to constrain the motion of the molecules more severely than in the liquid state.
  • Spherically shaped molecules generally have relatively high melting points, which in some cases approach the boiling point.

• Avogadro's Law: Volume and Amount

  • The model contains gas molecules under constant pressure.
  • Run the model and select different numbers of molecules from the drop-down menu.
  • What is the relationship between the number of molecules and the volume of a gas?
  • It was originally assumed that 1 hydrogen and 1 oxygen atom went into a water molecule.
  • Using Avogadro's Law, this experiment confirmed that 2 hydrogen and 1 oxygen form 1 water molecule.