Molecule and Molecular Formula

Molecular formula is a presentation of elements that form the compound; likewise, it indicates how many atoms of elements are used. Ex: Water molecule H2O1 has atomicity 3 ; Methane molecule C1H4 has atomicity 5.
Remark: subscript 1 is never written.

Source:

http://www.windows.ucar.edu/physical_science/chemistry/ch4_molecule_big_gif_image.html

Source:
http://www.sciencelearn.org.nz/contexts/icy_ecosystems/sci_media/images/water_molecule

Water molecule in the free conditions, O atom has 2e unpaired and the H-atom has 1e unpaired

Source:

http://commons.wikimedia.org/wiki/File:Electron_shell_008_Oxygen.svg

Source:

http://commons.wikimedia.org/wiki/File:Electron_shell_001_Hydrogen.svg

To be saturated O need 2e & H 1e to become a stable compound. To form a water molecule, these elements bond together in proportion 2H:1O

Source:
http://www.electrical-res.com/hydrogen-and-oxygen-form-water/

Covalent Bond

source:
http://www.youtube.com/watch?v=1wpDicW_MQQ

What is the covalent bond?

Chemical Stability and Electronic Configuration

The noble gases have 8 electrons on the outermost energy level, except He (2e). Such rule is applied to all compounds. When the molecule formed, it changes its electron configuration to full saturation: 8 electrons “Octet rule”. It is done either by losing, gaiting or sharing electrons.

source:

http://people.seas.harvard.edu/~jones/es154/lectures/lecture_2/covalent_bond/covalent_bond.html

What is the Octet rule?

Introduction

Our universe composed of 90 elements that cannot exist alone. They are present in arrangement: diatomic compounds. According to Avogadro’s hypothesis, “under the same condition, equal volume of gases contains the same number of molecules.” Example: He and H2. Hydrogen composed of two atoms because in mono-atomic state it is not stable. The connection between two atoms called “chemical bonding”. However, inert gases, such as He, Ne, Ar…, can exist alone. They called inert gases.

Source:

http://serc.carleton.edu/usingdata/nasaimages/index4.html

Which molecules are mono-atomic?

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