2. Properties of Materials

Explanation:

It is an object's capacity to bend  or stretch when we apply force  (push or pull). Objects that are flexible can bend or stretch effortlessly and revert to their original shape when the force is removed. 

Example:

When you press down on the rubber ball, you'll notice that it squishes under your fingers. But when you let go, the rubber ball bounces back to its round shape. This happens because rubber is flexible and can handle the force by going back to its original shape once the force is removed.

Fig. 2.3 Rubber flexibility

Explanation:

An object's texture can be described as how it feels.  It is common to use terms like smooth or rough, soft or hard, coarse or fine, matte or glossy, etc. to describe textures 2. 

Explanation:

The ability of a material to take in (absorb) another material, mostly a gas or liquid, is called absorbency. Different materials have different levels of absorbency.

Example:

Sponge is really good at soaking up liquids because it is very absorbent3. 

Fig. 2.4 Sponge is absorbant

Explanation:

Solubility is the term used to express how readily a substance can dissolve in a liquid.

Example:

A material is soluble in water when it fully dissolves in the liquid. 

When we add salt or sugar to water, after stirring for some time they dissolve in water.

Fig.2.5a Soluble Mixture

Non example:

Insoluble materials are materials that do not dissolve in the liquid.

Sand does not dissolve in water and is insoluble.

Explanation:

Objects that are  heavy for their size (denser than water) sink, and objects that are light for their size (less dense than water) float5.

An object's shape also determines if the object sinks or floats.

Watch this video to know more: 

Vid. 2.1 Float and sink6

Example:

A leaf floats in water. 

Fig. 2.6 Transmission of Light

Explanation:

Light transmission is the ability of the materials to allow light to pass through.

Transparent Materials: They're like windows; all the light can go through them, and you can see things clearly on the other side.

Translucent Materials: They let some light through, but it's not clear. When you look at things through them, they seem blurry or like vague shapes.

Opaque Materials: These are like solid walls for light; no light goes through them. When you try to look through them, you can't see anything on the other side, and they create shadows because they block light.

Example:

Transparent Materials: Air, glass, or water.
Translucent Materials: Frosted glass or waxed paper.
Opaque Materials: Wood, metal, or stone.

Explanation:

Ductility is the property of metal associated with its ability to be stretched into wire without breaking. 

Example:

Copper wires are used in electrical wiring because of their excellent ductile properties. When you stretch a copper wire, it can become thinner and longer without snapping.

Explanation:

Malleability is the property of metal associated with its ability to be hammered into a thin sheet without breaking.

Example:

Gold is the most malleable metal.

Fig. 2.7 Gold is Malleable

Watch this video to recap:8 

Vid. 2.2 Malleability and Ductility 

Non example:

Porcelain is a ceramic material that is more likely to fracture or chip rather than change shape when hammered. Porcelain is used for making delicate, decorative items.

Explanation:

It refers to the ability of a given material to conduct (transfer) heat.

Example:

Some cooking pots heat up quickly because they're made of materials like copper and aluminium that spread heat quickly. This helps cook food evenly.

Fig. 2.9a Metal used in cookware

Non example:

Wood does not conduct heat efficiently. That's why wooden handles are often used for cookware; they stay cooler to the touch than metal handles.

Explanation:

Lustre is a property of metals due to which they shine when cut or scratched.

Example:

Silver has a brilliant metallic lustre. When polished, it has a shiny and reflective surface

Fig. 2.10a Lustre in Metals

Non example:

Chalk is a non-example of lustre. It has a dull, matte appearance and does not reflect light in the same way that lustrous materials like gold or silver do.

Explanation:

The capacity of materials to produce a ringing sound when struck is called sonority. Most metals possess sonority. Hence, they are used in many instruments. Almost all non-metals are not sonorous.

Example:

A metal bell is a classic example of a sonorous material. When struck, it produces a ringing sound.

Fig. 2.11 Metal bells