Avogadro’s Constant

6.02 x 10^23 atoms = 12 grams

The mole is used in measurements in a way similar to the use of “dozens”.

  • The reason why we use moles in chemistry is because of the vast number of molecules and atoms involved in the calculations
  • Just like it’s easier to manage the thought of 2 dozen eggs instead of 24, scientists prefer to think of a reaction requiring 2 moles of carbon rather than 1,204,428,200,000,000,000,000,000 particles
  • The number is huge and unimaginable, a bit like the number of stars in the galaxy
  • Using the mole unit helps simplify calculations

Note: the symbol for mole is “mol”

The mole concept

The mole

The mole concept

The mole concept

Avogadro's constant and the mole

The mole is equal to 602 thousand billion billion!

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Sublimation is the process of turning from solid to vapor without going through the intermediate liquid phase.

Sublimation of Ice

We are all familiar with ice melting before it evaporates. However, in sublimation, the liquid phase is omitted. In order for a solid to sublime, it must exhibit a higher than usual vapor pressure and weak intermolecular attractions.… Read the rest

Atmospheric Pressure & Boiling Point

What is vapor pressure chemistry cartoon

What is vapor pressure?

Water always evaporates no matter what the temperature or atmospheric pressure is.

Even in the coldest of winter, snow and ice can evaporate by a process called sublimation. They can turn straight into vapor (the gaseous stage) without melting.

The vapor that escaped into the air whether by evaporation or sublimation had sufficient energy to break away from the intermolecular forces of the water.… Read the rest


Molality = mol solute / kg solvent

Molality is defined as the number of moles of solute per 1 (kg) of solvent.

  • Solute = particles you dissolve
  • Solvent = the liquid you use for dissolving the particles

Molality (m) = mol solute / kg solvent


Calculate molality (m) of 29.8 g of glucose (C6H12O6) dissolved in 622.8 g of water

Symbol Element Atomic weight Atoms
C Carbon 12.01 6
H Hydrogen 1.008 12
O Oxygen 16.00 6

Step 1.Read the rest

Colligative Properties of Solutions

Colligative properties of solutions

The characteristics of a solution such as the boiling point, freezing point and vapor pressure are known as colligative properties. Colligative properties apply only to solutions and not gases or solids.


The word colligative comes from the same Latin root that the word collection comes from.… Read the rest

Carbon to Carbon Bonds

Ethane is a hydrocarbon that contains a single carbon–carbon bond

Carbon-carbon bonds

A carbon atom has 4 valence electrons

A carbon atom has 4 valence electrons

A single bond

Most bonds that carbon form are single bonds. Single bond simply means sharing one pair of bonding electrons between two atoms and is represented by a single line. 

Two carbon atoms forming a single bond

Two carbon atoms forming a single bond

In ethane, two carbons atoms share a single bond

Structural drawing of an ethane molecule showing the single carbon to carbon bond

A double bond

A carbon atom can also form multiple bonds with other carbon atoms.… Read the rest

Covalent Bonding

In a covalent bond, two atoms share a pair of electrons


The term covalent bond is used to describe the bonds in compounds that result from the sharing of one or more pairs of electrons.

  • There are two types of covalent bonds – nonpolar and polar covalent bonds
  • In nonpolar covalent bonds, the electrons are shared equally between the two atoms
  • In polar covalent bonds, the electrons are are not shared equally and will be closer to the atom with the higher electronegativity
  • Please note: The electrons are shared, not transferred so there is no loss or gain of electrons

Covalent bond - polar and nonpolarRead the rest

4 Simple Steps – Chain Glucose Molecule

Glucose Regatta - Glucose Molecule - C6H12O6

Glucose C6H12O6

  • Glucose is a carbohydrate and it is one of the smallest units of sugar
  • Its chemical formula is C6H12O6
  • Glucose are hexoses – 6 carbon atoms sugars
  • In total, there are 24 atoms that form the molecule

Glucose molecular structure -1

Step 1:

Draw 6 carbon molecules and draw arms except for the first one

Glucose molecule step 1

Step 2:

Draw 5 hydrogen to carbon bonds
(4 on one side and 1 on the other)


Step 3:

Fill remaining spaces with ( OH ) group.

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The Octet Rule of Electron Configuration

Valence electron octet rule

What is the Octet Rule of Electron Configuration?

Electron configuration is the arrangement of electrons in each energy level or shell of an atom.

  • If the outer shell of an atom is not filled to its maximum level, the atom is still reactive and has a tendency to combine with other elements
  • The atom only becomes stable when it is filled to the maximum level it can hold in the outer shell
  • The octet rule is a rule of thumb that works most of the time with some exceptions
  • For more information on valence electrons, please click here >>

Chlorine and fluorine fulfilling the octet rule

Chlorine and fluorine are bonded to fulfill the octet rule

Fluorine has 7 valence electrons

Chlorine has 7 valence electrons

Chlorine and fluorine are bonded by sharing 1 electron each

Together they become a stable compound

Each atom now has 8 valence electrons (instead of 7) occupying its valence shell

smiley-163510__180Read the rest

Enthalpy, Entropy & Gibbs Free Energy

Gibb's free energy
 Enthalpy  Entropy Gibbs Free Energy
 icon-enthalpy  icon-entropy
Enthalpy is the amount of heat energy transferred (heat absorbed or emitted) in a chemical process under constant pressure. Entropy measures the amount of heat dispersed or transferred during a chemical process. Gibbs Energy is also known as energy available to initiate a chemical process and is determined under constant pressure and temperature.
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Condensation Polymerization

Condensation polymers are any kind of polymers formed through a condensation reaction where molecules join together–losing small molecules as by-products such as water or methanol.


Example – converting ethylene terephthalate to polyethylene

Step 1: Draw two different monomer molecular structure

Condensation Polymerization - Making Plyesters or PET

ester-linkageThis pretty symbol you see is called an ester linkage formed by combining acid and an alcohol.… Read the rest