| A | B |
|---|
| chemical bond | force of attraction that holds two atoms together |
| chemical bonding | the process by which chemical bonds are formed |
| cation | a positively charged atom that has lost electrons |
| anion | a negatively charged atom that has gained electrons |
| ionic bond | electrostatic force of attraction between a cation and anion to form an ionic compound |
| octet rule | electrons rearrange themselves in chemical reactions so atoms are stable with 8 electrons in their valence shell |
| dot diagrams | indicate the valence electrons in an atom or ion |
| Lewis (dot) structures | dot diagrams used to represent valence electrons in atoms and molecules |
| kernel | represented by chemical symbol in a dot diagram, consists of nucleus and non-valence electrons |
| covalent bond | formed when electron clouds overlap allowing electrons to be shared between two atoms |
| molecular substances | substances formed by atoms held together by covalent bonds |
| ionic compound (salt) | substances formed by ions held together by electrostatic attraction between atoms of opposite charge |
| molecular formula | shows type and number of atoms in a substance |
| structural formula | shows arrangement of atoms and represents their covalent bond with a line representing a pair of shared electrons |
| single bond | contains one pair of shared electrons |
| double bond | contains two pairs of shared electrons |
| triple bond | contains three pairs of shared electrons |
| hybridization | rearrangement of electrons within the valence orbitals such as sp orbital in carbon |
| VSEPR | valence shell electron pair repulsion model predicts the shapes of molecules due to the valence shell electrons repulsion |
| tetrahedral shape | occurs with 4 pairs of electrons when all 4 pairs are shared, bond angle 109 degrees, methane |
| pyramidal shape | occurs with 4 pairs of electrons when only 3 pairs are shared, bond angle 107 degrees, ammonia |
| bent shape | occurs with 4 pairs of electrons when only 2 pairs are shared, bond angle 105 degrees, water; also with 3 pairs of electrons when 2 pairs are shared, sulfur dioxide |
| linear shape | all 2 atom (binary) molecules |
| trigonal planar shape | occurs with 3 pairs of electrons when all 3 pairs are shared, bond angle 120 degrees, boron trifluoride |
| resonance | dot diagram representations do not match experimental results because electrons move back and forth between bond positions |
| paramagnetism | substances with unpaired electrons in valence shell’s spins do not cancel causing atoms to react with a weak magnetic field often associated with colored substances |
| polar covalent bonds | electrons shared unequally, electronegativity difference between 1.67 and 2 |
| nonpolar covalent bonds | electrons shared equally, electronegativity difference below 1.67 |
| polar molecule (dipole) | molecules that behave as if one side were positively charged and other side was negatively charged |
| hydrogen bond | attraction of polar molecules to electronegative atoms of neighboring molecules |
| metallic bonds | attractive forces that hold positive metallic atoms together in a shared cloud of valence electrons |
| ionic crystal (crystal lattice) | regular pattern formed by packed cations and anions resulting from a balance of the forces of attraction and repulsion |
| properties of molecular solids | relatively soft, brittle, nonconductive, low melting point, high vapor pressure, easy conversion to gas or liquid |
| properties of ionic solids | relatively hard, brittle, conductive as liquid or in solution, high melting point, low vapor pressure, high heat of fusion |
| properties of metallic solids | soft to very hard, malleable, conductive as liquid or solid, high melting point, low vapor pressure, some easy to melt |
