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 3 atoms. 

A water molecule has 2 hydrogen atoms and 1 oxygen atom.

Substances like sugar have many atoms in their molecules. 

A molecule of sugar has many atoms, including carbon, hydrogen and oxygen.

What is matter made of? atoms and molecules.

Matter is made of molecules, such as H20, which is the water molecule. 

Matter can be one of three states, solid, liquid or gas. 

Water and ice are the same substance, but they are in different states. 

These states depend on the temperature of the molecules. 

When we heat a substance, the molecules move faster and try to take up more space. 

When we cool a substance, the molecules move more slowly. 

When we cool a substance to its freezing point, it becomes a solid. 

What do the states of matter depend on? temperature

In a solid, the molecules move very little. 

Their positions are almost fixed. 

To be fixed means that their positions don't change.

If we heat the molecules, they move faster and away from each other. 

The solid begins to melt, like ice cream on a hot day. 

How can we change a solid into a liquid? heat it up

To change a solid into a liquid, add heat.

At a certain temperature, a solid begins to change into a liquid.

The temperature at which a solid changes into a liquid depends on the substances. 

For water, the solid begins to change into a liquid when its temperature rises to above 0 degree Celsius. 

For some substances, such as steel, the temperature at which it becomes a liquid is much higher. 

Steel often melts at around 1370 degrees Celsius.

At what temperature does ice begin to melt? below 0 degrees Celsius

If we continue to heat a liquid, the molecules move even faster. 

At a certain temperature, the liquid begins to change into a gas.

For water, the liquid begins to change into a gas at 100 degrees Celsius. 

That is the boiling point of water.

At what temperature does water boil? 100 degrees Celsius

Inside a star, such as our Sun, the temperature is very high. 

Everything inside the Sun is a gas. 

According to scientists, there are over 65 elements inside the Sun. 

These include oxygen and iron. 

Over 90 percent of the Sun is hydrogen gas.

What is the only state of matter inside the star？Everything inside the Sun is a gas.