bonding and chemical interactions Flashcards
why can elements past period 3 break the octet rule
expand into the d orbital
- However, some of the third-period elements (Si, P, S, and Cl) have been observed to bond to more than four other atoms, and thus need to involve more than the four pairs of electrons available in an s2p6 octet. This is possible because for n=3, the d sublevel exists, and it has five d orbitals.
- Size is also an important consideration: The larger the central atom, the larger the number of electrons which can surround it.
which elements have incomplete octets
H (2), He (2), Lit (2), beryllium (4) and boron (6)
boron
6
beryllium
4
ionic bonding
one or more electrons from an atom with low ionization energy ( energy needed to remove an electron = metal) are transferred to an atom with high electron affinity ( higher= wants more- def = the amount of energy released when atom gains an electron - exothermic) this is usually a nonmetal. Once one steals the others electron(s) - it becomes an anion and is attracted to the cation - this is the bond ( electrostatic attraction)
covalent
shared between 2 atoms
- typically 2 nonmetals that have simular electronegativity
- polarity depends on the difference between the two’s electronegativity
if both electrons are given by one of the atoms in the colvealent bond it is called a
coordinate colvalent
BP of ionic compounds
high - bc of the strength of the electrostatic force
other characteristics of ionic compounds
good conductors, disolve in water and other polar solvents, sold state form a crystalline lattice
bonding force of colvalent bonds
the electrons (both in the shared pair) feel an attraction to the two positive nuclei of the bonded atoms
to remember if nonmetals lose or gain electrons: Nonmetals …..
Nonmetals gain electons to become aNions and Negative
when an ionic bond forms
generally extremely exothermic (energy released)
- even if some energy input is needed (electron affinity- always endothermic) - the amount of energy given off when a salt lattice is HUGE - making in exothermic
properties of covalent compounds
they become there own lil molecules that have weak intermolecular reactions so they are poor conductors, low boiling point sand melting points- don’t break into constituent ions
bond order
number of shared electron pairs between two electrons
- single = 1 bond order
- double = bond order of 2
bond length
shorter with increasing bonds