Listening·States-of-Matter
Matter is made of atoms and molecules.
Water, for example, is the H2O molecule.
This means that a molecule of water has 3atoms.
A water molecule has 2 hydrogen atoms and 1oxygen atom.
Substances like sugar have many atoms intheir molecules.
A molecule of sugar has many atoms,including carbine, hydrogen and oxygen.
Matter is made of molecules such as the H2Owhich is the water molecule.
Matter can be in one of 3 states, solid,liquid or gas.
Water and ice are the same substance, butthey are in different states.
These states depend on the temperature ofthe molecules.
When we heat a substance, the moleculesmove faster and try to take up more space.
When we cool a substance, the moleculesmove more slowly.
When we cool a substance to its freezingpoint, it becomes a solid.
In a solid, the molecules move very little.
Their positions are almost fixed.
To be fixed means that their positionsdon’t change.
If we heat the molecules, they move fasterand away from each other.
The solid begins to melt, like ice cream ona hot day.
At a certain temperature, a solid begins tochange into a liquid.
The temperature at which a solid changesinto a liquid depends on the substances.
For water, the solid begins to change intoa liquid when its temperature rises to above 0 degrees Celsius.
For some substances, such as steel, thetemperature at which it becomes a liquid is much higher.
Steel often melts at around 1,370 degreesCelsius.
If we continue to heat a liquid, themolecules move even faster.
At a certain temperature, the liquid beginsto change into a gas.
For water, the liquid begins to change intoa gas at 100 degrees Celsius.
Inside a star, such as our sun, thetemperature is very high.
Everything inside the sun is a gas.
According to scientists, there are over 65elements inside the sun.
These include oxygen and iron.
Over 90% of the Sun is hydrogen gas.
