Chapter 9: Chemical Bonds Flashcards
the … electrons form bonds
valence
a lewis-dot symbol for an atom consists of the
symbol for the element surrounded by dots, one for each valence electron
electrons are usually removed from groups 1 and 2 because they have
low ionization energies
electrons are easily added to nonmetals because their
electron affinities are generally favorable
ionic bonding is the bonding that results from
electrostatic attraction between positively and negatively charged ions
when an ionic coompound forms, the number of electrons lost in forming the cations must
equal the number gained to form the anions
born-haber cycle: a process in which the formation of an ionic compond is shown as the
sum of five simpler reactions
lattice energy is the energy required to separate
one mole of an ionic crystalline solid into the isolated gaseous ions
lattice enrgy is always
positive
E=
kQ1Q2/ r
k is a
constant
Q1 and Q2 are the
charges on the two particles
r is the
distance of separation in the compound
equation for E known as
coulomb’s law
lattice energies are greatest for compounds made from
highly charged small ions
maximize …, minimize … to get the largest E
Q; r
ionic solids are stable because of
high lattice energies
ionic compounds are typically … with …
brittle solids; high melting points
covalent compounds are typically … or … at …
liquids; gases; room temperature
when covalent compounds are solids, they are
low melting
a covalent bond is a bond that results from
atoms sharing electrons
the bond length is the … between the … in a molecule
minimum energy distance; nuclei of two bonded atoms
bond length is determined by a … observed as the two atoms move ..
potential energy minimum; closer together
a covalent bond forms because two atoms sharing electrons are
lower in energy than the two isolated atoms
bonding pairs of electrons are
shared between two atoms
lone, or nonbonding, pairs of electrons are entirely
on one atom and are not shared
lewis structures show how valence electrons are
arranged among atoms in a molecule
lewis structures reflect the central idea that stability of a compound relates to
noble gas electron configuration
lewis structures show the .. and …, not the …
numbers; types of bonds; geometry of the molecule
The octet rule states that each atom in a molecule shares electrons until it is
Surrounded by eight electrons
In most Lewis structures oxygen makes … bonds and has … lone electrons; nitrogen makes … bonds and has … lone pair; carbon makes … bonds
Two; two; three; one; four
Single bond;
Shares one electron pair
Double bond:
Shares two electron pairs
Triple bond:
Shares three electron pairs
Bond order: the number of
Electron pairs that are shared between two atoms
Skeleton structure shows which atoms are
Bonded to each other in a molecule
Central atom: an atom bonded to
Two or more other atoms
Nonpolar
Equal sharing of electrons
Polar
Unequal sharing of electrons
The polarity of a compound can be determined by
Placing the compound in an electric field
If a molecule is polar it will no longer have a
Random orientation In the electric field
dipole moment is a measure of the
unequal sharing of electrons