Unit 3 Flashcards
chemical bond
mutual electrical attraction between the nuclei and valence electrons of different atoms that binds the atoms together
ionic bonding
chemical bonding that results from the electrical attraction between large numbers of cations and anions
covalent bonding
sharing of electron pairs between two atoms
nonpolar covalent bond
a covalent bond in which the bonding electrons are shared equally by the bonded atoms, resulting in a balanced distribution of electrical charge
polar covalent bond
covalent bond in which the bonded atoms have an unequal attraction for the shared electrons
molecule
a neutral group of atoms that are held together by covalent bonds
octet rule
chemical compounds tend to form so that each atom, by gaining, losing, or sharing electrons, has an octet of electrons in its highest occupied energy level
molecular compound
a chemical compound whose simplest units are molecules
chemical formula
the relative numbers of atoms of each kind in a chemical compound by using atomic symbols and numerical subscripts
molecular formula
shows the types and numbers of atoms combined in a single molecule of a molecular compound
diatomic molecule
molecule containing only two atoms
bond length
the distance between two bonded atoms at their minimum potential energy, that is, the average distance between two bonded atoms
bond energy
the energy required to break a chemical bond and form neutral isolated atoms
electron-dot notation
an electron-configuration notation in which only the valence electrons of an atom of a particular element are shown, indicated by dots placed around the element’s symbol
unshared pair/lone pair
pair of electrons that is not involved in bonding and belongs exclusively to one atom
lewis structures
formulas in which atomic symbols represents nuclei and inner-shell electrons, dot-pairs, or dashes between 2 atomic symbols to represent electron pairs in covalent bonds, and dots adjacent to only one atomic symbol represent unshared bonds
structural formula
the kind, number, arrangement, and bonds but not the unshared pairs of the atoms in a molecule
single bond
a covalent bond produced by the sharing of one pair of electrons between two atoms
resonance
bonding in molecules or ions that cannot be correctly represented b y a single Lewis structure
ionic compound
composed of positive and negative ions that are combined so that the numbers of positive and negative charges are equal
formula unit
the simplest collection of atoms from which an ionic compound’s formula can be established
C & C a chemical formula for a molecular compound with one for an ionic compound.
- most ionic compounds exist as crystalline solids, a three-dimensional network of positive and negative ions mutually attracted to one another
- in contrast to a molecular compound, an ionic compound is not composed of independent, neutral units that can be isolated and examined; the chemical formula of an ionic compound represents the simplest ratio of the compound’s combined ions that gives electrical stability
List and compare the distinctive properties of ionic and molecular compounds.
- difference in strength of attraction between basic units of molecular and ionic compounds gives rise to different properties in two types of compounds
- melting point, boiling point, hardness of compound dpeend on how strongly basic units are attracted to each other; molecular compounds have low melting and boiling point, ionic compounds have higher melting and boiling points, do not vaporize @ room temperature
- ionic compounds are hard but brittle (difficult to move one row of ions)
Write the Lewis structure for a poly atomic ion given the identity of atoms combined and other appropriate information.
- poly atomic ion: charged group of covalently bonded atoms
- if ion is negatively charged, add the total number of valence electrons to number of electrons corresponding to ion’s negative charge. if ion is positively charge,d subtract the total number of valence electrons a number of electrons corresponding to the ion’s positive charge