Chapter 3: Speaking with Pictures: Drawing Structures

CH2

The bonds between carbon and hydrogen are not explicitly shown but instead each carbon and the attached hydrogens are grouped together into a cluster (such as ________ or CH3)

Lewis structure

________: shows what atoms are connected to each other, and it shows where the electrons in the molecule reside.

Nitrogen

________ is trivalent because it has 3 bonds to other atoms (plus a lone pair) when its neutral.

resonance structure

Draw the ________ by moving the double- bond electrons onto the oxygen to create a species with a positive charge on carbon.

atoms lone pairs

The sum of a(n) ________ and bonds can not be greater than 4 for the second- row elements.

straight chain

Jagged line: represents ________ molecules, with each point (including the ends of the structure) representing a carbon atom.

Parentheses

________ with subscripts are used to abbreviate when two or more identical groups are attached to an atom.

pentagon

A(n) ________ is a five- carbon ring; and so forth.

Atoms

________ are fixed and can not move.

Arrows

________ can be used to convert one resonance structure into the other.

Hydrogens

________ attached to any atom other than carbon (atoms such as oxygen [O], sulfur [S], and nitrogen [N]) must be explicitly shown; only ________ attached to carbons are not shown.

NH2

________- has four nonbonding electrons, or two lone pairs of electrons (because there are two "dots "in every lone pair)

Valency

________: number of bonds around a neutral atom.

Dots

________: number of lone- pair electrons around the atom.

Triple bonds

________ are drawn in a straight line.

Line bond structure

________: most common method of structure drawing.

Single bonds

________ between two atoms are represented with a single line, signifying two shared electrons.

implicit hydrogens

If it shows a carbon that has two bonds, it must have two ________.

resonance arrow

The double- headed ________ shows that these resonance structures are equivalent, and a way of correcting the flaw in Lewis theory and accounting for the proper electron distribution.

three carbon

A triangle is a(n) ________ ring (which, of course, is the smallest possible ring size)

resonance structure

Electron- pushing arrows are used to convert one ________ into the next.

Lewis structure

A(n) ________ explicitly draws out all the bonds in a molecule, but this can be tedious so there is a shorthand notation.

Triple bonds

________ are represented with a triple line, signifying six shared electrons.

Resonance structures

________: used to to account for a flaw in showing the locations of certain lone- pair and pi electrons in Lewis structures (pi electrons are electrons found in pi bonds.

Dots

________= valence electrons- sticks- formal charge.

Lewis structure

shows what atoms are connected to each other, and it shows where the electrons in the molecule reside

Taking charge

Assigning formal charges

Dots

number of lone-pair electrons around the atom

Sticks

number of bonds off the atom

For example

for NH2, the formal charge equation for nitrogen in this molecule is

Valency

number of bonds around a neutral atom

$$__Condensed structure

__$$structure abbreviation of the full Lewis structure

Structural shorthand

Line-bond structures

Line-bond structure

most common method of structure drawing

Jagged line

represents straight chain molecules, with each point (including the ends of the structure) representing a carbon atom

So lonely

Determining lone pairs on atoms

NH2

has four nonbonding electrons, or two lone pairs of electrons (because there are two "dots" in every lone pair)

Resonance arrow

Used to indicate movement between resonance structures

Equilibrium arrow

Used to show reactions governed by equilibria

Reaction arrow

Used to show the change of molecules by a reaction

Note

Draw arrows from electrons toward where theyre going, never the other way around

Half-headed arrow

Used to show the movement of one electron; used for describing free radical reactions because these reactions involve the movement of single electrons

Resonance structures

used to to account for a flaw in showing the locations of certain lone-pair and pi electrons in Lewis structures (pi electrons are electrons found in pi bonds

Problem solving

Drawing resonance structures

Note

If you had stopped right after drawing the first arrow, it would have violated the octet rule

Example with acetone

the first resonance structure is uncharged so it contributes more to the overall hybrid

Example with acetone

the negative charge rests on the carbon and the positive charge rests on the oxygen