chem chapter 8 Flashcards
valance electrons of an atom for main group elements
s and p electrons with highest value of n
ex: carbon: 1s2 2s2 2p2, valence =2s2 2p2=4 (counting the exponents)
the core electrons are the ones not included
valance electrons for transition metals
s and d electrons with the highest value of n
ex) Titanium: [Ar] 4s2 3d2, valance =4
the core electrons are the ones not included
chemical reactions with core and valance electrons
-core: not participating in the chemical reaction or bonds (ignore them)
-valance electrons: chemical reactions result in the loss, gain, or rearrangement of valance electrons
atoms tend to ionize until they achieve…
the valance electron configuration of a noble gas (ns2 np6)
they will bond to achieve this
covalent compound
nonmetal + nonmetal
electrons SHARED through bonds
ionic compound
metal + nonmetal
electrons are TRANSFERRED and electrostatic forces keep the ions together
octet rule
atoms want to have 8 valance electrons and will bond to get there
lewis symbols of ions
have either 8 valance electrons or none
cations with lewis symbols
take away the electrons to make a positive charge
anions with lewis symbols
add electrons to equal a negative charge
when does a chemical reaction occur?
when two atoms have some of their valance electrons reorganized resulting in a net attractive force between the atoms (a chemical bond)
bonding pair
the SHARED electrons in covalent compounds
pure covalent compound
occurs when two identical atoms are bonded
ex) H + H goes to H2
what happens when two different atoms form a covalent compound?
the electrons are shared unequally
the bonding electrons will be closer to the more electronegative atom
polar covalent bond
bonding of two different atoms in a covalent compound
one atom has a partial negative charge and the other has a partial negative charge
(because the electrons will move to the more electronegative atom)
the greater the difference in electronegativity in two atoms…
the more polar the bond
metallic bond
metal + metal
when metals form a lattice and a sea of delocalized electrons are spread through the lattice
no or very little difference in EN=
covalent
moderate difference in EN=
polar covalent
large difference in EN=
ionic
can chemical bonds always be categorized as either ionic, metallic, or covalent?
no, chemical bonds exhibit characteristics of all three kinds of bonding
do ionic compounds form molecules?
no, they form lattice/crystal structures
lattice energy
indicates how strongly ions are attracted to each other in the solid state
when does lattice energy increase? What is the trend?
it increases with increasing ionic charge and decreasing ionic size
it wants a large charge or a small size!
