Chemistry Unit 3 Covalent and Ionic Bonding

Ionic compounds

atoms are “glued together” by the attraction of oppositely charges (cation - often metal) and anion -often nonmetal

Ionic bond

an attraction of two oppositely charged ions (non-metals to metals)

Metallic Bond

bonds only found in metals. They have loosely held valence electrons

Covalent Bond

when atoms share valence electrons to reach 8 valence electrons, a complete shell to be stable. Only non-metals covalently bond.

Poles

regions of charge within a molecule. occur when electrons are unevenly distributed, or non symmetrical.

nonpolar covalent bond

equal sharing of electrons, small electronegativity difference between bonded atoms and thus no development of pole

e.g. methane (CH4) nitrogen gas (N2), etc.

isomers

molecules with the same molecular formula but different structure

Resonance

where the atoms in an isomer are still connected (same connectivity) in the same sequence, but the lone pairs are different, but the connectivity is the same.

VSEPR

valence shell electron pair repulsion

this is when drawing a lewis structure, 1. spread the atoms out evenly, 2. give lone pairs more space than bonded pairs.

lewis structure

3-dimensional arrangement of atoms in a molecule.

electron pair is a line/two dots

formal charge

a calculation that determines the charge of an atom in a molecule

calculation = formal charge = valence electron - (1/2 bonded electrons + lone pair electrons)

carbon possible geometries

tetrahedral, trigonal planar, linear

H possible gemoetries

linear

Nitrogen possible geometries

trigonal pyramidal

linear

Fluorine possible geometries

linear

oxygen possible geometries

bent linear

polar covalent bond detail

unequal sharing of electrons

greater difference in electronegativity, electron pairs will be closer to nucleus, making it more negative, and the other end of the bond will be losing electrons so it is slightly positive. They become partial charges

partial charges are poles and dipole (2 poles)

polar bonding occurs when other atom is N, O, F, Cl, Br to any other nonmetal that is not one of these.

if electronegativity difference is 0

non polar pond, pure covalent

if change in electronegativity is between 0 and 0.65

nonpolar, bond type is nonpolar covalent

if electronegativity difference between 0.65 and 1.67

polar, and bond type is polar covalent

if difference in electronegativity is greater than 1.67

it is an ionic bond type.

ionic compounds uses nomelclature

last atom ends with -ide and the number of atoms are names, e.g. co2 is carbon dioxide p205 is diphosphorus pentoxide

hybridization

atoms attached to central atom+ lone pairs = orbitals, number of orbitals = number of letter thing

e.g. CH20, three atoms attached to central atom + 0 lone pairs

3 orbitals + 0 ,one pairs = 3 orbitals = sp2

valence electrons

electrons in the outermost shell

lone pairs of electorns

pairs of valence electrons that are not involved in bonding

why do bonds form

bonds form to satisfy the octet rule and making atoms more stable. Atoms do not WANT to bond, they HAVE to bond.

polarity

the distribution of electrical charge over the atoms in a molecule, leading to partial positive and negative charges.

symmetry

molecular structure which shows the equal distribution of electrons around the central atom, (if a structure is symmetrical, it is nonpolar, and vice versa)

dipole movement

measure of the polarity in a molecule. dipole arrows measures the movement of electron pair in the bond to one nucleus over another. dipole is two poles formed by difference in electronegativity.

IMF

the glue that holds atoms together, intermolecular forces

dipole - dipole IMF

London dispersion IMF

Metallic IMF

Ionic IMF

Hydrogen Bonding IMF

London dispersion

weak forces that exist in all atoms. Only IMF which exists in nonpolar covalent bonds. in singular non,metal atom.

Hydrogen bonding

Hydrogen FONding.. dipole-dipole interaction that is strongest

found in polar covalent bonding that have a H bond to an N, O, or F atom.

occurs when a hydrogen that is bonded to N, O or F is attracted to the lone pairs on another atom of N, O, or F.

octet rule

8 is gr8. atoms tend to bond to have 8 valence electrons in their outer shell to be stable.

electronegativity

attractive force of the atom that attracts electrons to itself.

building lewis structure

make sure that the octet rule is used

when doing isomers, you can also change the double bonds to triple bonds etc.

make sure to spread out the atoms PROPERLY, fully spread them out

make sure to count as properly make sure there are correct amount of lone pairs and double bonds etc.

only one that doesn't need to follow octet rule is Hydrogen. Ensure correct valence counts and atom connectivity.