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 one oxygen atom.
Substances like sugar have many atoms in their molecules.
A molecule of sugar has many atoms, including carbon, hydrogen, and oxygen.
Matter is made of molecules such as H2O, which is the water molecule.
Matter can be in one of three states, solid, liquid, and gas.
Water and ice are the same substance, but they are in different states.
These states depend on the temperature of 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 it’s freezing point, it becomes a solid.
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.
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 it's 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.
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. This is the boiling point of water.
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. This include oxygen and iron.
Over 90 percent of the sun is hydrogen gas.
Yesterday there was an important science text. Lisa,Tom and 20 other classmates took the text.
The text was about the states of matter and how they are different.
There were 25 questions on the text and they had 45 minutes to take it.
Here some of the text results.Two students got perfect scores.The lowest score was 68 out of 100.
The average score was 86.3. 11 students scored higher than average. 11 students had below average scores.
Tom missed 2 questions on the text,so his score was 92. His score was the 8 highest in the class.
Lisa missed 2 and a half questions,so her score was 90. Her score was the 10 highest score.
Her score was 4 points higher than the average score.
Lisa was disappointed with her text results. She studied hard for the text,but she still didn't do well.
As a result, she plans to study harder for the next text. The next text will be in about 2 weeks.
Tom was surprised and happy with his text results. He didn't study hard,so his result was better than he expected
He was also happy that he did better than Lisa did.
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