Unit 4 Chemistry Vocab

Covalent bond

• Force attraction that holds together two atoms

• Share a pair of valence electrons

• Typically only forms between atoms of nonmetals

Ionic bond 

• Electrostatic force holding ions together

• Creates an ionic compound

• Transfer of electrons

Bond energy/strength

• Energy required to break a covalent bond

• Higher bond energy = Higher stability = Less reactive

• Indirectly proportional to bond length

Polar covalent bond

• EN difference between 0.4-1.7

• Bonding electrons are shared unequally between the two atoms

Nonpolar covalent bond

• EN difference between 0-0.4

• Covalent bond where bonding electrons are shared equally between two atoms

Resonance structures

• Two or more Lewis structures used to represent the same covalent bonding in a molecule

• Bond order will NOT be 1.0

Lone pair

• Pair of electrons in a Lewis structure not being shared by atoms

Lewis structure 

• A visual representation of covalent bonds in a molecule

VSEPR theory

• Electron pairs repelling each other change shape of the molecule

• Theory helps us determine shape of a molecule

Trigonal planar

• 3 bonding areas

• No lone pairs

• Atoms are at the vertices of an equilateral triangle!

• 120 degree angle

Tetrahedral

• 4 bonding areas

• No lone pairs

• Each face is an equilateral triangle

• Angle is 109.5 degrees

Bent

• 2 bonding pairs

• 1-2 lone pairss

• Literally bent

• Angle is 104.5

T shaped

• 3 bonding pairs

• 2 lone pairs

Square pyramidal

• 5 bonding pairs

• 1 lone pair

Octet rule

• Most atoms tend to form compounds that give them 8 valence electrons

Duet rule

• Atoms that only need 2 valence electrons to be satisfied

• Hydrogen and helium

Dipole

• Molecule with a negative pole and positive poles

Hybridization

• Mixing of atomic orbitals in an atom to produce a set of hybrid orbitals to allow for better bonding

Diatomic molecules

• Molecules made of two atoms

• Homonuclear = Two same atoms

• Heteronuclear = Two different atoms

Bond length

• Length of bonds

• Inversely proportional to bond energy

Double bond and Triple bond

• Additional covalent bonds for when two atoms share more than 2 electrons

• Double = 2 pairs of electrons

• Triple = 3 pairs of electrons

Electronegativity

• How much an atom will pull shared electrons in a chemical bond

Octahedron

• 6 bonding pairs

• 0 lone pairs

• 90 degree angles + <90

Trigonal pyramidal

• 3 bonding pairs

• 1 lone pairs

Linear

• 2 BP and 0 LP

• 2 BP and 3 LP

• 2 BP and 4 LP

Seesaw

• 4 BP

• 1 LP

Square planar

• 4 bonding pairs

• 2 lone pairs

Trigonal bipyramidal

• 5 bonding pairs

• 0 lone pairs