2. Water is a chemical compound with the chemical
formula H2O.
A water molecule contains one oxygen and two
hydrogen atoms connected by covalent bonds.
Water is a liquid at standard ambient
temperature and pressure, but it often co-exists
on Earth with its solid state, ice, and gaseous
state (water vapor or steam).
Water also exists in a liquid crystal state near
hydrophilic surfaces
3.
4. Water is one of the most important substances on earth. All
plants and animals must have water to survive. If there was
no water there would be no life on earth.
Apart from drinking it to survive, people have many other
uses for water. These include: cooking
• washing their bodies
• washing clothes
• washing cooking and eating utensils; such as billies,
saucepans, crockery and cutlery
• keeping houses and communities clean
• recreation; such as swimming pools
• keeping plants alive in gardens and parks
• Water is also essential for the healthy growth of farm crops
and farm stock and is used in the manufacture of many
products.
5.
6.
7. Water never leaves the Earth. It is
constantly being cycled through
the atmosphere, ocean, and land.
This process, known as the water cycle,
is driven by energy from the sun. The
water cycle is crucial to the existence
of life on our planet.
8. During part of the water cycle, the sun heats up
liquid water and changes it to a gas by the
process of evaporation. Water that evaporates
from Earth’s oceans, lakes, rivers, and moist soil
rises up into the atmosphere.
9. The process of evaporation from plants
is called transpiration. (In other words,
it’s like plants sweating.)
10. As water (in the form of gas) rises higher in the
atmosphere, it starts to cool and become a liquid again.
This process is called condensation. When a large
amount of water vapor condenses, it results in the
formation of clouds.
11. When the water in the clouds gets too
heavy, the water falls back to the earth.
This is called precipitation.
12. When rain falls on the land, some of the water is
absorbed into the ground forming pockets of water
called groundwater. Most groundwater eventually
returns to the ocean. Other precipitation runs directly
into streams or rivers. Water that collects in rivers,
streams, and oceans is called runoff.