Chemistry

Basics

Given some element

Where

Cations: Positively （＋） Charged
Anions: Negatively （−） Charged

Mnemonic

Cations are Pawsitive

Conventions on homework

When a question says, determine the energy of 1 ㏖ of photons, the unit will be ᴶ/㏖.

SI Prefixes

Value	Prefix	Symbol
	deca
	hecto
	kilo
	mega
	giga
	tera

Value	Prefix	Symbol
	deci
	centi
	mili
	micro
	nano
	pico

Classification of Matter

Overview

Mixtures

Heterogeneous mixture

Where the prefix Hetero- means different

The Atom and Nuclear Chemistry

Isotopes and Subatomic Particles

Electrons and Quantum Mechanics

Average Atomic Mass

If the average atomic mass of boron is , what is the percent abundance of boron-11 （mass of ） if the only other isotope is boron-10 （mass of ）? Given the formula for average atomic mass:

Therefore in summary, we are given the following known quantities

With the following unknown quantities

And asked to find the percent abundance of boron-11 （）. Therefore our equation is

We have two unknowns, but luckily we can use the following fact/relation and therefore express the percent abundance of boron-10 in terms of the percent abundance of boron-11

Therefore

But we aren't done, we have to compute significant figures.

Therefore, we round our answer to 2 sig figs, yielding

Molecules and Compounds

Terms

Electronegativity: Can be used to to determine type of bond based on electronegativity difference.
Ionic Bond
Covalent Bond
Polar Covalent Bond: Sharing of electrons.
Hydrogen Bond: Hydrogen is bonded with an electronegative element.

Prefixes

Prefix	Value
mono-
di-
tri-
tetra-
penta-

Prefix	Value
hexa-
hepta-
octa-
nona-
deca-

Formula Summary

Formal Charge （Option 1）

Given some element which has number of valance electrons, and a lewis diagram of bonded （） electrons and non-bonded （） electrons, the formal charge for the given element in the lewis structure is

For the given quantities

Formal Charge （Option 2）

Given some element which has number of valance electrons, and a lewis diagram of some number of bonds （） and dots （）, the formal charge for the given element in the lewis structure is

For the given quantities

Note: each bond is 2 electrons, but counts as one bond.

Polyatomic Ions

Remembering the number of oxygens

General

Given a set of oxygens in increasing order

Where

For example

Given some element or compound ionically bonded with such

For example

The following table denotes the naming conventions therein

Prefix	Prefix Meaning （relative to suffix）	Suffix	Oxygen Order	Example
Prefix	Prefix Meaning （relative to suffix）	Suffix	Oxygen Order	Formula	Name
Per-	More than	-ate	Highest #		Perchlorate
		-ate	Higher #		Chlorate
		-ite	Lower #		Chlorite
Hypo-	less than	-ite	Lowest #		Hypochlorite

Oxygen vs No-Oxygen Comparison

Prefix	Suffix	Meaning	Example	Name
Per-	-ate		or	Persulfate
	-ate			Sulfate
	-ite			Sulfite
Hypo-	-ite			Hyposulfite
	-ide	No oxygennon-metal		Sulfide

In summary

Per*ate

Greater than

*ate
*ite
Hypo*ite

*ate

Less than

Per*ate

Greater than

*ite
Hypo*ite

*ite

Less than

Per*ate
*ate

Greater than

Hypo*ite

Hypo*ite

Less than

Per*ate
*ate
*ite

Generally

per-ate	Used in the ion with the largest number of oxygen atoms
-ate-ite	Polyatomic ions of oxygen
hypo-ite	Used in the ion with the lowest number of oxygen atoms
-ide	Non-metal, no oxygens

Determining The Charge^†

Warning

Phosphate （） is the only one that violates this rule!

Example for Hydrogen Carbonate

†

Source

Notes

When naming an ionic compound, the name of the cation is followed by the name of the anion. Monatomic anions are named with the ending -ide.

Periodic Properties of the Elements

Note, electron affinity is not the same as electronegativity!

Terms

Isoelectronic: Atoms with the same number of electrons.
Ionization energy
Predict Metallic Character Based on Periodic Trends

Expanded Octet （Exceptions to the Octet Rule）

All non-metals from period 3 to period 8 of the Periodic Table, can have expanded octets.

Quantum Mechanical Models of the Atom

Terms

Pauli Exclusion Principle: No two electrons in an atom can have the same four quantum numbers.; Pauli’s Principle prevents two electrons with the same spin from existing in the same subshell, each subshell will be filled with one spin direction before they are filled with the opposite spin. This is the second of Hund’s Rules.
Aufbau Principle: This pattern of orbital filling is known as the aufbau principle （the German word aufbau means “build up”）.
Hund’s rule: When filling degenerate orbitals, electrons fill them singly first, then with parallel spins.; I.e. start by filling boxes with single 'upward' arrows, and then once all of such boxes are maxed out, then you add double arrows pointing in opposite directions.; Pauli’s Principle prevents two electrons with the same spin from existing in the same subshell, each subshell will be filled with one spin direction before they are filled with the opposite spin. This is the second of Hund’s Rules.
Coulomb’s Law

Pauli's Exclusion Principle

Each election has a unique set of four quantum numbers （i.e. see quantum numbers）. They are

Overview

Values

Name	Symbol	Unit	Description	Range
Wavelength		Any unit for distance	Distance between two analogous points	Always Positive
Frequency	or （nu）		Number of cycles	Always Positive
Energy		（joule）	Amount of energy （） in a light packet

Constants

Name	Symbol	Unit	Value
Speed of Light
Planck's constant		Energy multiplied by time joule-seconds

Other Formulas

Heisenberg's Uncertainty Principle

Where

is the uncertainty in position.
is the uncertainty in velocity.
is the mass of the particle.
is the plank's constant.

In general it states that the more you know about an electrons position, the less you know about it's velocity.

Energy of an Electron in an Orbital with Quantum Number in a Hydrogen Atom

Energy of an Electron in an Orbital with Quantum Number for any atom

Where is the atomic number of the given element.

Change in Energy That Occurs in an Atom When It Undergoes a Transition between Levels （Further Details）

and

If is negative, energy is being released.
If is positive, energy is being absorbed.

Ionization Energy

Where

is the electron number
the point on the table where you see the highest difference/delta.

Atomic Spectroscopy

The Principal Quantum Number （n）（Hydrogen Atom）

For the hydrogen atom, the energy of an electron in an orbital with quantum number is given by

Therefore the difference in energy is given by the following

The Principal Quantum Number （n）（Any Atom）

For the hydrogen atom, the energy of an electron in an orbital with quantum number is given by

TODO

Where is the atomic number of the given element.

Electron Configuration

Examples

Electron configuration for

Since the electron configuration for Argon is

Electron configuration for

Beginning with the electron configuration for

Remove the electrons from the term with the higher electron state. Warning! Do not just remove the electrons from the rightmost term since the rightmost term may be a lower electron state. For instance given

is in a higher electron state
is in a lower electron state

Alternatively, to compute the lowest energy orbital, add the principle quantum number （） to the The angular momentum quantum number （） to get the orbital with the lowest energy. Therefore

Given and

NVM this is an exception to the rule...

TODO move this somewhere else...

As shown

Therefore the electron configuration for is:

Electron configuration for

It would appear that the electron configuration for would be

But this is wrong! It's actually

How-tos

What are the valence electrons?

Given

The valance electrons will be the ones in the highest energy state. Therefore

Therefore there are valence electrons.

Given

The valance electrons will be the ones in the highest energy state. Therefore

Therefore there are valence electrons.

Quantum Numbers

Overview

Symbol	Description
	The principle quantum number
	The angular momentum quantum number
	The magnetic quantum number
	The spin quantum number

The Principle Quantum Number （）

Value of	Value of	Orbital Sublevel

Angular Momentum Quantum Number

Value	Result

Value of	Value of