Chapter 12 Flashcards
two types of bonds
ionic and covalent
ionic bond
an electrostatic force between oppositely charged particles or ions - involves the transfer (loss and gain) of electrons
ionic compounds
composed of metals and nonmetals
covalent bond
formed by the sharing of electrons between two atoms - half filled orbitals overlap
covalent compounds
composed of two or more nonmetals - called covalent or molecular
non polar covalent bond
results from the equal sharing of electron pairs
polar covalent bonds
results from the unequal sharing of electron pairs
electronegativity (electron affinity)
a measure of an atoms ability to attract electrons to itself - increases across a period and decreases down a group
what determines the type of bond
the difference between electronegativities of the atoms - the greater the difference in electronegativity the more polar the bond
electron configuration of ions
group a or main group metals form ions by losing enough electrons to achieve the electron configuration of the previous noble gas - nonmetals form ions by gaining electrons to achieve the electron configuration of the next noble gas
dot diagrams
show the symbol of the element with dots representing its valence electrons - dot diagrams can be used to show how ionic compounds are formed
atoms and ion sizes
cations are always smaller than the parent atom because when valence electrons are lost the remaining electrons are attracted closer to the nucleus, valence electrons are lost and there is now fewer levels - anions are larger than the parent atom because gaining electrons lessens the attraction between the electrons and the nucleus which creates a larger size
polyatomic ions
charged particles composes of 2 or more atoms, but the individual atoms are held together by covalent bonds
lewis structure
used to show how the atoms in a covalent bond or molecular compound are arranged
VSEPR
valence shell electron pair repulsion - the electron pairs (bonding and non bonding) around the central atom assume positions as far from one another as possible to minimize repulsion
shape of a molecule
determined by the number of bonds and unshared pairs of electrons around the central atom
linear
2 bonds, no unshared pairs
trigonal planar
3 bonds, 0 unshared pairs
tetrahedral
4 bonds, no unshared pairs
pyramidal
3 bonds, 1 unshared pair
bent
2 bonds, 2 unshared pairs
angular
2 bonds, 1 unshared pair
molecular polarity
molecules are classified as polar or non polar
polar molecules
have a separation of charge due to polar bonds - the unequal sharing of the electron pairs causes one end of the molecule to have a positive charge and the other end to have a negative charge
non polar molecules
contains non polar bonds - the electron pair is shared equally and no separation of charge occurs
exception to polar bonds
molecules that contain polar bonds but have complete symmetry are non polar - the symmetry causes the poles to cancel each other out
exception to octet rule
atoms that have an empty d sublevel can have more than an octet of electrons around the central atom - by the promotion of electrons, atoms can end up with more than 4 half filled orbitals
trigonal bipyramidal
5 bonds, 0 unshared pairs
seesaw
4 bonds, 1 unshared pair
t-shaped
3 bonds, 2 unshared pairs
linear 2.0
2 bonds, 3 unshared pairs
octahedral
6 bonds, 0 unshared pairs
square pyramidal
5 bonds, 1 unshared pair
square planar
4 bonds, 2 unshared pairs
resonance structures
molecules that can have more than one acceptable lewis structure - contains a double bond, 1 central atom, follows octet rule
bond
the force that holds atoms together in a compound
