6.1 Intro to covalent bonds 6.2 Covalent Nomenclature 6.3 Electron Dot Notation and Lewis Structures 6.4 Polarity and Intermoleular Forces 6.5 VSEPR Theory
covalent bond
A chemical bond that involves sharing a pair of electrons between atoms in a molecule
What're covalent bonds generally formed by?
The are generally formed by 2 non-metals or 1 non-metal and 1 metalloid
How can covalent bonds form?
through atoms of non-metals coming together and combining like puzzle pieces into to covalent bonds by sharing their VEs.
physical property - crystalline structures
Covalent Compounds can form crystalline structures because their atoms share electrons, thus creating a stable, repeating pattern in a 3-dimensional structure
physical property - low melting points
Covalent Compounds have low melting points because their forces of attraction are weak. Meaning it will take less heat/energy to break/split bonds
physical property - liquid/gases @ rm temp.
Covalent compounds have weak forces of attraction that is not enough for them to maintain a solid composition.
physical property - Soft and Brittle
Covalent Compounds have weak forces of attraction which lets layers slide, making them soft. They are brittle because the bonds can be broken easily
physical property - don't transfer heat very well
physical property - little energy release
Covalent compounds have little energy release because when forces of attraction are overcome. This is because it takes little force of attraction to connect molecules, meaning it will take little energy to separate them
physical property - electrical conductivity
Covalent Compounds don't conduct electricity well when dissolved because they don't break into ions, making no way for electricity to travel as there is no free-flowing energy/charge in the solution
How are covalent compounds named?
They are named using prefixes because elements can bond in multiple ways
naming covalent compounds rule #1
the the first element is an single atom we DO NOT use mono
naming covalent compounds rule #2
second element will always use a prefix and make it end in -ide
Naming Binary Covalent Compounds
(prefix of element #1 [besides mono])(element #1)
+ (prefix of element #2)(element #2)(replace with -ide)
electron-dot notation
shows an atom that is ready to bond and the VE are represented by dots and the AS represents the rest of atom
Lone Pairs
A set of a pair of a electrons that belong to an atom but is not involved with the bonding
How to draw an element's electron Dot Notation
Write elements AS
IMAGINE a box around the AS
Determine the # of VE in the atom by looking at the G#
Draw dots around the AS (each side must have one before you pair them)
Lewis Structure
A structural formula in which electrons are represented by dots; dot pairs or dashes between two atomic symbols represent pairs in covalent bonds
How to Draw a Lewis Structure
add the valence electrons for all the atoms in the molecule
determine the central atom (least electro-negative besides Hydrogen)
draw single bonds in the form of lines towards the central atom
put all remaining VEs on atoms as lone pairs (except H)
Turn lone pairs into double or triple bonds if needed to give every atom an octet/duet by replacing them towards the atoms of higher electro-negativity
single bond
long/weak
double bonds
medium/moderate - sharing 2 pairs of e- between 2 atoms
triple bonds
short/strong - sharing 3 pairs of e- between 2 atoms
expanded octets
molecules that posses atoms utilizing an expanded octet = hypervalent
Polarity
the distribution of electrical charge over the atoms joined by the bond
polar molecule
molecule with an unequal distribution of charge, resulting in the molecule having a positive and a negative region of charge
nonpolar molecule
molecule with a symmetrical distribution of charge that is, resulting in the molecule having no regions of partial charge.
polarity range
dependent on what source you use
non polar covalent bond
the difference in EN between 2 atom will be 0<x<=0.40 - present in covalent compounds
Polar Covalent
the difference in EN between 2 atom will be 0.4<x<=1.80 - present in covalent compounds
Ionic
the difference in EN between 2 atom will be 1.8<0- present in ionic compounds
dipole moment
the mathematical product of the separation of the ends of a dipole and the magnitude if charges AKA the dipole avg
the product of the charge and the separation distance (bigger atom = bigger dipole moment)
when there is uneven distribution of charge within the molecule
intramolecular force
the force (attraction) between atoms within a compound
intermolecular force
the force (attraction or repulsion) that is between separate molecules
London dispersion forces
the result of attraction between separate molecules due to e- moving which create a temporary dipole
present in ALL covalent compounds
highest possible IMF for noble gasses and non-polar covalent compounds
dipole-dipole forces
the result of attraction between separate molecules due to permanently existing dipoles
present in ALL POLAER covalent compounds
highest possible IMF for polar covalent compounds
hydrogen bond
weak attraction between a hydrogen atom and another atom (N,O,F)
present in ALL POLAR covalent compounds that have these three elements with H
Highest Possible IMF that has these possibilities
Molecular Geometry
Describes the specific shape of the molecule as a result of e- wanting their own space
VSEPR stands for
Valence Shell Electron Pair Repulsion
electron geometry
geometry that describes a generalized shape since they want their own space (atoms and electrons will affect the shape)
No lone pair on A
EG and MG is the same
VSEPR Designation
A = central atom
X = atoms bonded to A
E = lone pair of E-