10/16 notes Flashcards
is CaCO3 brittle or maleable
brittle because it is an ionic compound
what are covalent compounds
non metals + non metals
if only non metals are involved, what is the ionization energy
ionization energies are high, so it is unfavorable to lose (and therefore transfer) electrons
bohr model solution
share electrons by overlapping valence shell to achieve noble gas configuration
orbital view of covalent bond
overlap one-electron orbitals -> forms covalent bonds
The strength of a covalent bond is proportional to the amount of overlap between atomic orbitals; that is, the greater the overlap, the more stable the bond.
what tells us if the covalent bond is stable
wave functions
properties of bonding molecular orbital
1)constructive interference
2)add waves
3)energetically favorable
4)puts electron density in the bond region between the nuclei
what causes repulsion
pauli exclusion principle
anti-bonding molecular orbital properties
1)destructive interference
2)has a node
3)energetically unfavorable
4)because of node: zero probability of finding the electron
what makes a polar covalent bond
electrons pair is unequally shared. One element is more electronegative than the other, pulls electron density towards itself, and starts to acquire a negative electronegative charge. The other atom acquires positive electronegative charge as its electrons are being pulled away
how are electrons shared in nonpolar covalent bond
equally
what is electonegayvity
the ability to attract shared electrons in a chemical bond
what is electron affinity
the energy change from gaining an electron
how does electronegativity change according to the periodic table
increases as you go up periodic table and increases as you go right across periodic table.
what element is most electronegative
flourine
more polar bonds have larger ________ in _______ between 2 elements
differences; electronegativity
polar bonds have _______ _________ ________ that strengthens bonds
additional electrostatic attraction
what is polarizability
how ‘free’ valence electrons are to move away from the nucleus
effective nuclear charge and polarizability for high EN elements
have large effective nuclear charge and low polarizability
nuclear charge and polarizability for low EN elements
smaller effective nuclear charge and higher polarizability
why dont non metals transfer electrons like ionic bonds
Because they have low electronegative differences. Non metals also cant transfer electrons as quickly
according to the octet rule
Atoms will tend to lose, gain, or share electrons such that their valence electrons shell resembles that of a noble gas
what is octet rule
an atom will be most stable when surrounded by 8 electrons in a valence shell. An atom with 8 electrons will bond with an atom that does not.
According to orbital overlap concept
the formation of a covalent bond between two atoms results by the pairing of electrons present in the valence shell having opposite spins.
why are noble gases not assigned electronegativity values
Since noble gases already have a full valence shell of electrons and are stable, they have no need for attracting electrons so no, they do not have electronegativity.
what is polarity
when an entity contains two distinct and opposite poles that can either attract or repel each other
How does electronegativity help us rank how polar a bond is?
The greater the difference in electronegativity, the more polarized the electron distribution and the larger the partial charges of the atoms.
In the Periodic Table, which atoms are more polarizable, which are less polarizable, and why?
polarizability decreases from left to right, but increases down on columns of the periodic table. Larger molecules are generally more polarizable than smaller ones.
what is least electronegative element
cesium
