States of Matter物质的状态
Matter is made of?atomsand?molecules.物质是由原子和分子构成的。
Water, for example, is the H2O molecule.?例如，水是H2O分子。
This means that a molecule of water has 3 atoms.?这意味着一个水分子有3个原子。
A water molecule has 2?hydrogen atoms and 1?oxygen atom.一个水分子有两个氢原子和一个氧原子。
Substances like sugar have many atoms in their molecules.?像糖这样的物质分子中有许多原子。
A molecule of sugar has many atoms, including carbon, hydrogen and oxygen.糖分子有许多原子，包括碳、氢和氧。
Matter is made of molecules, such as H20, which is the water molecule.?物质是由分子组成的，比如水分子H20。
Matter can be one of three states, solid, liquid or gas.?物质可以是三种状态之一，固态、液态或气态。
Water and ice are the same substance, but they are in different states.?水和冰是同一种物质，但它们处于不同的状态。
These statesdependon the temperature of the molecules.?这些状态取决于分子的温度。
When we heat a substance, the molecules move faster and try to take up more space.?当我们加热一种物质时，分子运动得更快，并试图占据更多的空间。
When wecoola substance, the molecules move more slowly.?当我们加热一种物质时，分子运动得更快，并试图占据更多的空间。
When we cool a substance to its freezing point, it becomes a solid.?当我们把一种物质冷却到冰点时，它就变成固体。
In a solid, the molecules move very little.?在固体中，分子几乎不动。
Their positions are almost fixed.?它们的位置几乎是固定的。
To be fixed means that their positions don't change.被固定意味着他们的位置不会改变。
If we heat the molecules, they move faster and away from each other.?如果我们加热分子，它们会运动得更快，彼此远离。
The solid begins to melt, like ice cream on a hot day.?固体开始融化，就像热天的冰淇淋。
To?change a solid into a liquid, add heat.要把固体变成液体，加热。
At a certain temperature, the?solid begins to change into a?liquid.在一定的温度下，固体开始变成液体。
The temperatureat which a solid changesi nto a liquid depends on the substances.?固体变成液体的温度取决于这些物质。
For water, the solid begins to change into a liquid when its temperature rises to above 0 degree Celsius.?对于水来说，当温度上升到0摄氏度以上时，固体就开始变成液体。
For some substances, such as steel, the temperature at which it becomes a liquid is much higher.?对于某些物质，如钢，它变成液体的温度要高得多。
Steel often melts at around 1370?degrees Celsius.钢通常在1370摄氏度左右熔化。
If we continue to heat a liquid, the molecules move even faster.?如果我们继续加热液体，分子运动得更快。
At a certain temperature, the liquid begins to change into a gas.在一定的温度下，液体开始变成气体。
For water, the liquid begins to change into a gas at 100 degrees Celsius.?对于水来说，液体在100摄氏度时开始变成气体。
That is the?boiling point of water.这是水的沸点。
