bonds

• The proton is located in the nucleus.
• Protons have a +1 relative charge.
• Protons have a relative mass of 1.
• The neutron is located in the nucleus.
• Neutrons have a 0 relative charge.
• Neutrals have a relative mass of 1.
• Electrons are located in the electron cloud (orbiting the nucleus).
• Electrons have a -1 relative charge.
• Electrons have a relative mass of 1/1840.
• A chemical bond involves the electrons only - the nuclei of the different atoms are not affected.
• The reason atoms interact, according to the quantum theory, is that all atoms attempt to:

  1. to be electrically neutral (# of protons = # of electrons).
  2. to acquire a more stable electron structure of the nearest noble gas.
• In quantum mechanics, an orbital is a specific volume of space in which an electron of a certain energy is likely to be found.
• An orbital may be thought of as a sort of 3D space that defines where an electron may be.
• An orbital may be occupied by one or two electrons, but not more than two.
• For the bonding study, we are only concerned with an atom's valence orbitals, the volumes of space that electrons can occupy in an atom's highest energy level.
• A valence orbital can theoretically share an electron with another atom if the valence orbital is occupied by a single electron (this single electron is called a bonding electron).
• A full valence orbital, occupied by two electrons, has a repelling effect on electrons in any nearby orbitals (those two electrons occupying the same orbital are called a lone pair).
• Orbital: each orbital may contain two, one, or no electrons.
• Non-valence electrons: pairs of electrons that are in the inner shells.
• Valance electrons: any electron that is in the outside shell (these can be paired or single electrons).
• Lone pair: has a repelling effect on electrons in any nearby orbitals.
• Bonding electron: a single electron can theoretically share that electron with another atom.
• The first energy level has room for only one orbital with a maximum of two electrons (for example: hydrogen, the smallest reactive atom with the simplest structure, has only one energy level).
• Energy levels above the first contain four orbitals, that is, eight electrons maximum.
• Octet rule is usually obeyed by main group atoms.
• F, O, N, and C atoms always obey the octet rule when bonding.
• An orbital may be unoccupied, or it may contain one or two electrons (this means that two electrons may share the same region of space at the same time).
• Electrons spread out to occupy any empty valence orbitals before forming electron pairs.
• Empty orbital:

  • has 0 electrons.
• Half-filled orbital:

  • has 1 electron
  • has an unpaired electron
  • that electron is a bonding electron
• Filled orbital:

  • has two electrons
  • these electrons are a lone pair
  • those electrons are non-bonding electrons
• Main group elements are group 1,2, 13-18.
• A chemical formula is a format used to express the structure of atoms (the formula tells which elements and how many of each element are present in a compound).
• Isomers are compounds in which two molecules can have the same number of atoms, and thus the same molecular formula, but can have completely different physical and chemical properties because of differences in structural formula.
• Molecular formula: is a chemical formula of a molecular compound that shows the kinds and numbers of atoms present in a molecule of the compound.
• Empirical formula: is a formula that shows the elements in a compound in their lowest whole-number ratio.
• Lewis structure: shows the valence electrons of each atom and which type of bonds are involved.
• Structural formula: displays the atoms of the molecule in the order they are bonded.
• Perspective drawing: it shows which atoms are above and below the plane of the paper by using wedges and dashes respectively; the central atom is always assumed to be in the plane of the paper (wedges come towards you and dashes go away from you).
• Ball and stick model: illustrates the 3D arrangement of the atoms in space and the shape of the molecule.