Water molecule
Overview.
Water molecule.
Overview.
About 70% of the Earth's surface is covered with water.
About 60% of our body is just water.
Water participate in most chemical reactions,
specially in the body.
Water is so essential for life,
that scientists, when they search for evidence of life,
in other planets, they look for the existence of water.
Water molecule.
In the water molecule, oxygen shares a pair of electrons,
with 2 hydrogen atom to form the co-valent bond.
The water molecule has chemical property, of attracting electrons.
This is called electronegativity.
Oxygen is more electronegative, then hydrogen.
Oxygen has a negative charge, and hydrogen has a positive charge.
Water is a polar molecule, capable of forming polar co-valent bonds.
Water molecules interact, because of this polarity.
The positive charge of the hydrogen atom,
is attracted to the negative charge of the oxygen atom,
in another water molecule.
This forms a hydrogen bond.
When water is in liquid form, these bonds are weak,
and last for only trillionth of a second.
This is why molecules of water, are not organised,
like in a snowflake.
The ice crystals in a snowflake, have 6 water molecules,
in a hexagonal structure.
This causes snowflakes to create a myriad of unique patterns.
When water molecules stick to itself, it is called cohesion.
When water molecules stick to other substances,
it is called adhesion.
The hydrogen bonds in water, are strong enough,
to let the insect float in water.
When water freezes, the hydrogen bonds keep the water molecules, further apart.
This makes ice less dense than water.
Ice is about 9% less dense than water.
This causes ice to float on water.
This property is crucial for marine life.
When a sea or lake freezes, only the top layer freezes into ice.
This acts like a insulation for the water below.
Marine life is possible even in winter, because of this.
The polar nature of water molecules, gives it a property of cohesion and adhesion.
These properties help trees to draw water from its roots,
and take it to the top branches of the tree.
Some trees could be thousands of feet tall.
Even then, the tree is able to transport water, to its top most branches.
The xylem in the tree transports the water up.
Water moves like beads on a string.
Cohesion causes water molecules, to stick to each other.
Adhesion causes the water molecules to stick to the xylem.
Using these properties the tree, is able to transport water.
Water can dissolve many other molecules.
This is specially true for polar molecules.
Water is such a good solvent, that it is sometimes called as a universal solvent.
Sodium chloride dissolves in water.
This N a+ ion is attracted to the negative charge, in the water molecule.
The Cl- ion is attracted to the positive charge , in the water molecule.
This causes sodium chloride to disassociate, and dissolve in water.
This is a typical example of how substances dissolve in water.
Water can accept an acid or a base.
It can accept a proton, to become H3O+ or hydronium.
It can donate a proton, to become an O H- ion, called hydroxide.
The cells in our body allow chemical reactions,
to happen more frequently, in the presence of water.
Water also facilitates the transport of nutrients and waste,
in living organisms.
It also helps to maintain internal body temperature.
Lipids are non polar.
They do not dissolve in water.
There are said to be hydrophobic.
Cell membranes have a unique structure.
The inner layer is hydrophobic.
The outer layers are hydrophilic, or water loving.
This separates and protects the liquid cytoplasm, in the cell.
Water has a high specific heat.
It can absorb a lot of heat in summer.
In winter it can release heat.
The oceans in our planet, acts like reservoirs of heat.
It stores heat in summer, and releases heat in winter.
When temperatures increase, water becomes water vapour.
This is carried by the wind, and makes the air humid.
Water vapour is responsible for weather conditions,
like rainfall and snow.
Even plants and trees release water vapour into the atmosphere.
Water molecule are very versatile.
Because of the large varieties of properties they have,
water is widely used in living organisms.
Water also has many industrial applications.
Water also plays a leading role, in the climate of the planet.