Points to Remember

POINTS TO REMEMBER

* Particle arrangement within the state of matter gets disturbed upon heating. The disturbance is seen either as expansion or contraction.

* A process in which liquid changes into vapour on heating is called evaporation.

* A process in which solid changes into liquid on heating is called melting or fusion.

* A process in which gas changes into a liquid is called condensation.

* A process in which liquid changes into solid is called freezing.

* Physical changes are the changes in which only physical properties of a substance undergo a change and there is no change in its chemical composition.

* Solid substances are usually purified by the process of crystallization.

* Evaporation is the technique used to separate dissolved solids from a solid-liquid mixture.

* Certain solid substances like camphor, naphthalene get converted into gas directly without becoming liquid upon heating by sublimation.

* Changes that occur with the formation of new substance with different chemical composition or transformation of a substance into another substance with the evolution or absorption of heat or light energy are termed as chemical changes.

* Changes that repeat themselves after a definite interval of time are called periodic changes.

* Changes that do not repeat themselves after a definite interval of time and occur randomly are called non-periodic changes.

* Changes in which heat is absorbed are known as endothermic changes.

* Changes in which heat is released are known as exothermic changes.

ICT CORNER

CHANGES AROUND US

This activity helps the students to understand the effect of heat on matters

PROCEDURE :

Step 1: Type the URL link given below in the browser or scan the QR code. A page opens with a glass full of ice with a play button near to it.

Step 2: Press Play button. It opens into another page with the set up of temperature and change of phases.

Step 3: Set the temperature and phases. Press the play button below.

Step 4: Do it with different options. Then a next page button will come

Step 5: Go there you will end with a small quiz.

Changes Around Us URL:

https://interactives.ck12.org/simulations/chemistr y/phases-of-matter/app/index.htmlm

*Pictures are indicative only

*If browser requires, allow Flash Player or Java Script to load the page.