WATER AND ITS PROPERTIES
One of the things that makes our planet special is the presence of liquid water. Water is fundamental for all life; without it every living thing would die. It covers about 70% of Earth's surface and it makes up 65-75% of our bodies (82% of our blood is water). Even though water seems boring - no color, taste, or smell - it has amazing properties that make it necessary for supporting life.
The chemical composition of water is H2O - two hydrogen atoms and one oxygen atom. Water has special properties because of the way these atoms bond together to form a water molecule, and the way the molecules interact with each other.
Polarity
When electrons are not shared equally in a covalent bond, the molecule is described as polar. Water molecules are ploar. This means that while water molecules are neutral as a whole, one end of the water molecule tends to have a positive charge while the other has a negative charge. The oxygen end has a slight negative charge while the hydrogen end has a slight positive charge. Each end of a water molecule is attracted to the opposite charged end of another water molecule. Water's polarity is responsible for the "stickiness" or cohesion between the molecules.
COHESION
Cohesion is the attraction between molecules of the same substance. Due to hydrogen bonding water is very cohesive. Water's cohesion causes molecules on the surface of the water to be drawn inward causing "surface tension". This property allows insects to walk on water.
ADHESION
Adhesion is the attraction between molecules of different substances.Thats why water usually stick to subtances .
Capillary Action
Cohesion of water causes capillary attraction, which is the ability of water to move upward in small spaces. Cohesion makes it possible for water to move up the fibers of a plant. This is how plants get the water they need to survive. In addition, it moves water upwards in soil. Cohesion of water also causes surface tension, water's invisible skin which allows water striders to walk on water
Cohesion of water causes capillary attraction, which is the ability of water to move upward in small spaces. Cohesion makes it possible for water to move up the fibers of a plant. This is how plants get the water they need to survive. In addition, it moves water upwards in soil. Cohesion of water also causes surface tension, water's invisible skin which allows water striders to walk on water
Surface Tension
Water is considered the "universal solvent" because its bipolar molecule enables it to dissolve a wide variety of substances. Solubility is affected by polarity. Polar substances can dissolve other polar substances. Non-polar substances dissolve other non-polar substances. Polar substances and non-polar substances, however, do not mix.
Water is considered the "universal solvent" because its bipolar molecule enables it to dissolve a wide variety of substances. Solubility is affected by polarity. Polar substances can dissolve other polar substances. Non-polar substances dissolve other non-polar substances. Polar substances and non-polar substances, however, do not mix.
Density
Another property of water is density during phase changes. The density of most substances increases when a liquid becomes a solid. Solid water is actually less dense than liquid water. It is for this reason that ice floats. Can you imagine a world where ice sank? Lakes would freeze from the bottom up, killing many fish. Frozen water in the polar regions would sink and change the ocean levels. The fact that ice floats is essential for the survival of many aquatic ecosystems and ultimately life on Earth.
Another property of water is density during phase changes. The density of most substances increases when a liquid becomes a solid. Solid water is actually less dense than liquid water. It is for this reason that ice floats. Can you imagine a world where ice sank? Lakes would freeze from the bottom up, killing many fish. Frozen water in the polar regions would sink and change the ocean levels. The fact that ice floats is essential for the survival of many aquatic ecosystems and ultimately life on Earth.
Snow Flakes
Q: How are snowflakes formed?
A: A snowflake begins to form when an extremely cold water droplet freezes onto a pollen or dust particle in the sky. This creates an ice crystal. As the ice crystal falls to the ground, water vapor freezes onto the primary crystal, building new crystals – the six arms of the snowflake.
That’s the short answer.
The more complex explanation is this:
These ice crystals that make up snowflakes are symmetrical (or patterned) because they reflect the internal order of the crystal’s water molecules as they arrange themselves in predetermined spaces (known as “crystallization”) to form a six-sided snowflake.
Ultimately, it is the temperature at which a crystal forms — and to a lesser extent the humidity of the air — that determines the basic shape of the ice crystal. Thus, we see long needle-like crystals at 23 degrees F and very flat plate-like crystals at 5 degrees F.
The intricate shape of a single arm of the snowflake is determined by the atmospheric conditions experienced by entire ice crystal as it falls. A crystal might begin to grow arms in one manner, and then minutes or even seconds later, slight changes in the surrounding temperature or humidity causes the crystal to grow in another way. Although the six-sided shape is always maintained, the ice crystal (and its six arms) may branch off in new directions. Because each arm experiences the same atmospheric conditions, the arms look identical.
Q: So, why are no two snowflakes exactly alike?
A: Well, that’s because individual snowflakes all follow slightly different paths from the sky to the ground —and thus encounter slightly different atmospheric conditions along the way. Therefore, they all tend to look unique, resembling everything from prisms and needles to the familiar lacy pattern.
A: A snowflake begins to form when an extremely cold water droplet freezes onto a pollen or dust particle in the sky. This creates an ice crystal. As the ice crystal falls to the ground, water vapor freezes onto the primary crystal, building new crystals – the six arms of the snowflake.
That’s the short answer.
The more complex explanation is this:
These ice crystals that make up snowflakes are symmetrical (or patterned) because they reflect the internal order of the crystal’s water molecules as they arrange themselves in predetermined spaces (known as “crystallization”) to form a six-sided snowflake.
Ultimately, it is the temperature at which a crystal forms — and to a lesser extent the humidity of the air — that determines the basic shape of the ice crystal. Thus, we see long needle-like crystals at 23 degrees F and very flat plate-like crystals at 5 degrees F.
The intricate shape of a single arm of the snowflake is determined by the atmospheric conditions experienced by entire ice crystal as it falls. A crystal might begin to grow arms in one manner, and then minutes or even seconds later, slight changes in the surrounding temperature or humidity causes the crystal to grow in another way. Although the six-sided shape is always maintained, the ice crystal (and its six arms) may branch off in new directions. Because each arm experiences the same atmospheric conditions, the arms look identical.
Q: So, why are no two snowflakes exactly alike?
A: Well, that’s because individual snowflakes all follow slightly different paths from the sky to the ground —and thus encounter slightly different atmospheric conditions along the way. Therefore, they all tend to look unique, resembling everything from prisms and needles to the familiar lacy pattern.
some of their shapes depending on temperature
- 32-25° F - Thin hexagonal plates
- 25-21° F - Needles
- 21-14° F - Hollow columns
- 14-10° F - Sector plates (hexagons with indentations)
- 10-3° F - Dendrites (lacy hexagonal shapes)
If water and ice are clear, then why does snow look white?
In simple words the answer snowflakes have so many light-reflecting surfaces they scatter the light into all of its colors, so snow appears white Or we can say beacuse the way the human eye perceives color. Even though the light source might not be truly 'white' light (e.g., sunlight, fluorescent, and incandescent all have a particular color), the human brain compensates for a light source. Thus, even though sunlight is yellow and scattered light from snow is yellow, the brain sees snow as white because the whole picture received by the brain has a yellow tint that is automatically subtracted.
Transparency
Water is relatively transparent to visible light, near ultraviolet light, and far-red light, but it absorbs most ultraviolet light, infrared light, and microwaves. Most photoreceptors and photosynthetic pigments utilize the portion of the light spectrum that is transmitted well through water. Microwave ovens take advantage of water's opacity to microwave radiation to heat the water inside of foods. The very weak onset of absorption in the red end of the visible spectrum lends water its intrinsic blue hue
It is the only natural substance found in all three physical states at the temperatures that naturally occur on Earth.
New research from the Aerospace Institute of the University of Stuttgart in Germany supports the theory that water has a memory—a claim that could change our whole way of looking at the world . Even though they do not have enough evidence it is a famous
topic of discussion for many scientists.
topic of discussion for many scientists.
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