Question

Why do atoms form bonds?

What are oxygen’s options for reaching 8 valence electrons?

How is a polar covalent bond different from a nonpolar covalent bond?

How does a hydrogen bond work? Does it alter the number of valence electrons?

What are the special properties of water, and what is the cause of this special behavior?

What happens to ionic bonds in water?

How does each of the following affect the properties of the atom?

            Protons:

            Neutrons:

            Electrons:

Answer 1

Atoms can be referred to as the building blocks of matter. Atoms makes molecules and molecules make compounds. Before understanding why atoms form bonds let us have a brief look at what atoms are made up of. Initially it was thought that atoms are the smallest matter but eventually scientist discovered that an atom is not the smallest matter but is made of even more smaller particles called protons, neutrons and electrons. Every atom has a nucleus and electrons are revolving around this nucleus which is made up of one or more protons and neutrons. The protons are positive charged, electrons are negatively charged while neutrons carry no charge.

1. With this general idea about an atom, let us now understand why atoms form bonds, Every thing on the planet wants to achieve a stable state where their is minimum energy requirements. Similarly an atom also want to be a stable one thus to achieve stable states they form bonds with the other. Forming a bond essentially means they always strive to complete their outer shell electrons. once the outer shell electrons are complete the atoms are more stable.

2. Atoms are stable only when their outermost shell is filled. Noble gases have an octet of valence electrons naturally that is why they dont share valence electrons with any other atoms but some atoms like oxygen do not have a stable outer most configuration. Oxygen has 6 valence electrons and needs 2 more electrons to become a stable atom. Now it has to form bonds with other atoms to make itself stable. Let us consider an example of water molecule. Each hydrogen atom has one electron which it shares with an individual oxygen atom and forms a covalent bond. Because of which each hydrogen atom has a duet of valence electrons and oxygen atom now has an octet valence electrons thus making both of them stable.Thus oxygen can form covalent bonding to achieve a stable state.

3. Polar covalent bonds are formed when electrons are not shared equally and they occur when there is a difference in electronegativity between covalently bonded atoms. while, non polar covalent bonds are formed when electrons are shared equally by both members of the bond. Let us look deeper into the differences

Polar covalent bonds	Non polar covalent bonds
They have charge( either positive or negative)	They lack charge.
Have a defined axis	They lack this feature
When dissolved in water they undergo solvation because they form ions	They do not dissociate to produce ions and hence do not undergo solvation.
Conduct electricity is aqueous solution	They do not conduct electriciity in aqueous solution
have high melting and boiling points when compared to non polar covalent bonds	Comparatively lower Melting and boiling points
Stronger vanderwaal's force of attraction exists between molecules	weaker vanderwaal;s force of attraction exists between molecules.

4. Hydrogen bond works due to high electronegativity difference. Therefore only oxygen, nitrogen and flourine can form hydrogen bonds. These make the hydrogen atom positively charged by pulling the electrons towards themselves.

5. Special properties of water is due to the hydrogen bond. polar molecules have weak partial negative charge at one region and a partial positive elsewhere because of which when they are close together they attract positive and negative charges of the nearby molecule. In water molecules each molecule of water is hydrogen bonded to 4 others.

The attraction created by hydrogen bonds keep water over a wide rage of temperature than is found for any other molecule size. also the energy required to break multiple hydrogen bonds cause water to have high heat of vaporization. The molecules are attracted through their hydrogen bonds to water vapor.

6. There are no ionic bonds in water because to form an ionic bond one will need ions but water has no ions. it can form only covalent bonds with other molecules. Example, covalent bonds between 2 hydrogen atom and one oxygen atom forms a covalent bond.

7. Protons contribute to the weight and gives positive charge to the atom. Neutrons are also responsible for the weight of the atom but give no charge. Electrons do not contribute to the weight but they give a negative charge.