Earth Hour

Dear all,

Please be reminded of your ICT homework for this weekend! E-mail your situational writing Unit 4 to me through your lead.com.sg

Here is a recap of what you have been introduced for the new topic on water the changes of states.

Solids have a definite shape and volume. The particles that make up a solid are closely packed together and do not have much space to move. Thus, solids keep their shape.

Liquids flow and do not have a definite shape. Liquids take the shape of their containers. The particles that make up a liquid are further apart than solids, and they can move around more readily. This allows liquids to flow and spread out.

Gases also flow and do not have a definite shape. The particles that make up gases are farther apart than liquids, so gases can spread out in all directions to take the whole space of a container.

When ice melts, it goes from a solid to a liquid. Heat causes the temperature of the ice to increase and particles to gain more energy. They are able to move faster and flow, causing a solid to change into a liquid.

When you pour liquid water into an ice cube tray and put it in the freezer, you will get ice, which is a solid. When water freezes, it loses heat and energy. Particles slow down and become more packed together. This causes liquids to change into solids. The freezing point of pure water is 0 degrees celcius.

Adding heat to water can cause it to change states. When a tea kettle full of liquid water is put on a stove, the temperature begins to rise. Particles gain more energy and are able to move and spread out more. When water boils, the liquid turns to a gas. This process is called evaporation. You may have observed that wet clothes will dry out if they are hung in a warm, sunny spot. The water in the clothes evaporates into the air.

Liquids can change into gases, but gases can also change into liquids. You would have noticed droplets of water that collect on the side of a cup or glass. Water vapor is a gas in the air and when it comes in contact with the cool glass, the temperature decreases. The particles lose energy, turning the gas into a liquid. This process is called condensation.

[ Earth Hour ]

Today is earth hour. From 8.30pm to 9.30pm, lets' play our part by switching off the lights for one hour. Save the earth by doing our part!

Sincerely,
Mr. Nelson Ong