Mole | Definition, Unit, Symbol and Examples|

-


Mole is one of the seven basic physical quantities. It is used to measure quantity of a chemical substance in term of numbers of elementary particles - elementary particles of a chemical substance can be atoms, molecules, ions, formula units etc - just like one dozen of any thing has  12 items of that thing. 

1 mole of any substance= 6.022x10^23 elementary particles/mol.

Like
 1 dozen of any thing= 12 items/dozen.

DEFINITION
 A mole of any substance has exactly 6.022140766x10^23 elementary particles of given substance.This number is usually written in round off as 6.022x10^23.This number is known as Avogadro's number. Symbol used for Avogadro's number is NA.

SYMBOL & UNIT
Symbol designated for mole is "n" and its unit is "mol".

EXAMPLES
1 mole of sodium(Na) = 6.022x 10^23 atoms/mol.
1 mole of water(H2O) = 6.022x 10^23 molecules/mol.
1 mole of sodium ions(Na+) = 6.022x10^23 ions/mol.
1 mole of sodium chloride(NaCl) = 6.022x10^23 formula units/mol.

NOTE
In above examples elementary particles are
  •  In 1st example sodium is an elemental substance, its elementary particle is atom.
  • In 2nd example water is molecular compound, it's elementary particle is molecule.
  • In  3rd example, sodium ion is an ionic species, it's elementary particle is an ion.
  • In the 4th example, sodium chloride is an ionic compound its elementary particle is the formula unit.

Comments

Post a Comment

For any query you are always welcome. Feel free to contact me.

Popular posts from this blog

Alkanes Are Called PARAFFINS WHY?

-
Alkane are the hydrocarbons, all carbon and hydrogen bonds are single covalent bond- all are sigma bonds. Sigma bonds are strong bonds where bonded electrons are tightly held between bonded nuclei. So sigma bonds are inert - have very little reactivity to other reagents like oxidizing , reducing, electrophile , nucleophile, acids and bases. Another factor contributes towards little affinity of alkanes is low polarity of C and H bonds. Electronegativity of carbon is 2.5 and that of hydrogen os 2.1, hence electronegativity difference is just 0.4. which is negligible. Alkane are considered as non- polar molecules. So they are inert towards all sort of reagents.  That os reason alkane are also called PARAFFINS mean little affinity.
Read more

Ionic( cation and anion) size difference from neutral parent atom?

-
Image
Q: Why cation is smaller than its parent atom ? An atom has equal number of positive protons and negative electrons. This atom becomes cation after losing one or more electrons.Due to this imbalance between negative charge electrons and positive charge protons. Protons in Nucleus exerts more force of attraction on electronic shells. As a result cation becomes smaller than its parent atom. for example if we take Na atom it has 11 electrons in shells and 11 protons in nucleus. To become cation, Na loses its one electron from outermost shell. So one electron become less than proton , so more force of attraction exerts on electrons and size of cation becomes small. Q: Why anion is greater than its parent atom? An atom has equal number of positive protons and negative electrons. Atom becomes anion after gaining one or more  electrons. Due to this imbalance between negative charge electrons and positive charge protons.Nuclear charge ( charge due to protons) exerts less at...
Read more

Ionic Bond Formation/ Ionic Compound Formation

-
Image
Ionic bond Formation: In ionic bond formation cation ( formed from metal atom) which is formed by lose of electron/s and gets positive charge  gets attached  to anion (formed from non-metal) by electrostatic force of attraction. Anion is formed by accepting that/those electron/s donating by cation. in case of ionic bond there is no bond by electrons rather opposite charged ions are attached just due to opposite charges. Here we will understand the ionic bond formation by sodium chloride (NaCl) . Sodium ion (Na+)Formation : Sodium(Na) is an atom being atom it is neutral. Its atomic number is 11 means it contains 11 protons in nucleus and 11 electrons in shells. Its valence shell (outer most shell which determine valency) has one electron as shown in the figure. to get stable by octet rule it loses  its one electron from its valence shell and get configuration of nearest nobel gas i.e neon(Ne) as shown in figure Sodium ion Na+ Formation Chloride ion(Cl- i...
Read more