Organic Chem

nucleus of an atom

contains protons and nuetrons

ion

something that has electrical charge

atomic number (Z)

number of protons

mass number (A)

number of protons and nuetrons

valence electrons

electrons in the outer most shell (participate in bonding)

molecule

collection of atoms that are attached by chemical bonds

chemical bond

2 positively charged core atoms mutually attached to the negative charged electrons that are shared between them

checklist for a legitimate lewis structure

must show the correct number of total valence electrons, the sum of valence electrons around each hydrogen must be 2, the sum of valence electrons around each C, N, O, or F must be 8 (octet rule)

formal charge

formula: group # - # of lines - # of dots (helps draw diagrams, does not equal to actual charge)

oxygen formal charge pattern

normally makes 2 bonds and 2 lone pairs

formal charge without formula

more bonds than expected = more positive, fewer bonds than expected = more negative, carbon is the exception to the rule

X

placeholder for halogens (F, Cl, Br, I)

R

placeholder for Hydrogen or an alkyl group (molecule made only of carbon and hydrogen)

Z

placeholder for any atom or group of atoms

What is the formal charge of any nitrogen with four bonds?

positive

What is the formal charge of any nitrogen with three bonds?

neutral

What is the formal charge of any nitrogen with two bonds?

negative

What is the formal charge of any oxygen with three bonds?

positive

What is the formal charge of any oxygen with two bonds?

neutral

What is the formal charge of any oxygen with one bond?

negative

What is the formal charge of any halogen (X) with two bonds?

positive

What is the formal charge of any halogen (X) with one bond?

nuetral

What is the formal charge of any halogen (X) with zero bonds?

negative

What is the formal charge of any carbon with only three bonds?

positive

What is the formal charge of any carbon with four bonds?

neutral

What is the formal charge of any carbon with three bonds and a lone pair?

negative

Valence Shell Electron Pair Repulsion Theory (VSEPR)

electron domains repel each other and electrons around a central atom will orient themselves to minimize the electron-electron repulsion between the domains.

bond angle with two electron domains

180 degrees (BeH2, O2N+, CO2, HCN)

bond angle with three electron domains

120 degrees (BH3, H3C+, CH2, H2CO)

bond angle with four electron domains

109.5 degrees (CH4, NH3, H2O, H4N+)

Bond Angle

angle defined by any three atoms in a molecule

Both the HCH and HCO bond angles of H2CO (formaldehyde) are very close to 120°, but one is slightly smaller than the other. Predict which is smaller, and explain your reasoning

HCH bond angle is smaller because the greater electron density in the double bond of the HCO angle creates stronger repulsion against nearby bonds

what are the 5 molecular shapes

linear, bent, trigonal planar, pyramidal, tetrahedral

what molecular shape is this?

bent

what molecular shape is this?

trigonal planar (3 electron domains, no lone pair, it is flat)

what molecular shape is this?

pyramidal (4 electron domains, 3 bonds, 1 lone pair)

what molecular shape is this?

tetrahedral (4 electron domains, 4 bonds, no lone pair)

what molecular shape is this?

linear (2 electron domains)

A student makes the following statement: "The shape of water is tetrahedral because the four electron pairs about oxygen are approximately 109.5° apart and point to the corners of a tetrahedron." What misconception does this statement convey?

confuses electron pair geometry with the actual molecular shape.

orbital

the 3d region of space where the electron cloud is likely to be found

electron cloud

a mist of negative charge concentrated in a region of space (like in a bond between two atoms)

how can orbitals be filled?

Each orbital can be empty (zero e-), half filled (one e-), or full (two e-)

What is the maximum number of electrons that can fit in a single orbital (2s, 2px , 2py , or 2pz )?

2 electrons

which is lower in potential energy, an electron in a 2s orbital or in any of the three 2p orbitals?

An electron in a 2s orbital is lower in potential energy than an electron in any of the three 2p orbitals because the territory of an s orbital is closer to the nucleus than that of a p orbital in the same shell

how is a covalent bond formed?

by an overlap of orbitals

what are the two types of orbitals

Head to head overlaps called sigma bonds and side to side overlaps called pi bonds

single bond type

one sigma bond

double bond type

one sigma bond and one pi bond

triple bond type

one sigma bond and 2 pi bonds

hybridization

involves combining s and p orbitals to form an equal number of new orbitals that are averages of the originals

sp3 hybrid orbital angle

109.5 degrees

sp2 hybrid orbital angle

120 degrees

why can single bonds can rotate freely but double bonds cannot?

the pi portion of a double bond prevents the bond axis from rotating

sp hybrid orbital angle

180 degrees

what molecular shapes does sp3 hybridized produce?

tetrahedral, pyramidal, bent 109

what molecular shapes does sp2 hybridized produce?

trigonal planar, bent 120