Properties of materials

Question 1

Chemical properties of materials are:

Answer 1

thewayanelementorcompoundreactswithotherchemicalsubstances.
The main chemical properties of materials are:
heat of combustion
toxicity
oxidation state
Radioactive elements can change molecular bonds in living matter such as human tissue, causing cell division, mutation and even death.

Question 2

Heat of combustion

Answer 2

The amount of heat released per unit mass or unit volume of a substance when the substance is completely burned and undergoes complete combustion with oxygen, typically measured in units of energy per unit mass.

Question 3

Toxicity

Answer 3

A toxic material is defined as a material that releases a chemical in sufficient quantities to kill cells either directly or indirectly. Toxicity is the ability of a substance to cause harmful effects on living organisms when they encounter it.

Question 4

Oxidation state

Answer 4

The total number of electrons that an atom either gains or loses to form a chemical bond with another atom. It is a measure of the electronic charge distribution around an atom, indicating how many electrons it has gained or lost compared to its neutral state.

Question 5

Electrical and magnetic properties

Answer 5

The main electrical and magnetic properties of materials are:
conductivity
resistance
magnetism

Question 6

Metal classification

Answer 6

Ferrous alloys
Pure non-ferrous
Non-ferrous alloys

Question 7

Ferrous alloys

Answer 7

contain iron
almost all are magnetic
little resistance to corrosion and prone to rust
good electrical and thermal conductivity

Question 8

Pure non-ferrous

Answer 8

do not contain iron
are usually not magnetic
usually more resistant to corrosion

Question 9

Non-ferrous alloys

Answer 9

mixtures either of different metals or of a metal and small quantities of other substances
require a protective finish

Question 10

Thermoset plastics

Answer 10

Once heated and moulded, thermoset plastics cannot be reheated and remoulded.
The molecules of these polymers are cross-linked in three dimensions and therefore they cannot be reshaped or recycled.
The bond between the molecules is very strong.

Question 11

Thermoplastic plastics

Answer 11

Thermoplastics can be reheated and reshaped in various ways. They become mouldable after reheating as they do not undergo significant chemical change. Reheating and shaping can be repeated.
The bond between the molecules is weak and becomes weaker when reheated, allowing reshaping.
These types of plastics can be recycled.

Question 12

Elastomers

Answer 12

Elastomerscan deformand thenreturn to their original shapealmost instantly. Their molecules are like springs, which can be compressed.

Question 13

Hardwood

Answer 13

Hardwoods come from deciduous or broad-leafed trees. They grow slower than softwoods, so they are more expensive.
You can distinguish hardwoods by the structure of the wood grain. The wood grain is characterised by intricate patterns that vary from straight lines to refined swirls or waves. These characteristics contribute to the strength and durability associated with hardwood.

Question 14

Softwood

Answer 14

Softwoods come from coniferous trees that have needles instead of leaves. Softwoods grow faster than hardwoods and so are cheaper they are also easier to work with as they are typically softer than hardwoods.
This makes them ideal for using in the construction trade because they are cheap and relatively renewable with their fast-growing speeds.
Softwoods tend to possess a simpler grain structure than hardwoods that is characterised by straight parallel lines with fewer aesthetic nuances.

Question 15

Manufactured board

Answer 15

Manufactured boards are timber sheets produced by gluing wood layers or wood fibres together.
Manufactured boards are often made with waste wood materials.
They are inexpensive so are often used instead of real woods.They do not look as good as real woods so are often covered with a thin layer of real wood which iscalled veneer this improves their appearance.

Question 16

What is a composite material?

Answer 16

A composite material combines two or more types of materials. The properties of each material in the composite complement each other and produce a material with improved properties.
A composite material takes the form offibres, sheets or particles in a matrix (glue).
The fibres, sheets or particles can be made from textiles, glass, polymers, wood and carbon. The matrix can be made from thermoplastics, thermosetting polymers, ceramics and metals.

Question 17

What is a mechanical property?

Answer 17

Mechanical properties arepropertiesthat a material displays as a reaction to forces. They include:

strength
hardness
toughness
elasticity
plasticity
ductility
durability
malleability

Question 18

Strength

Answer 18

ability of a material to withstand compression, tension andresist deformation when force is applied.

Question 18

Hardness

Answer 18

ability to withstandscratching, denting, piercing or cutting.

Question 19

Toughness

Answer 19

ability to withstand sudden loading and shock; it is measured by the total energy that the material can absorb

Question 20

Elasticity

Answer 20

ability of a material to return to its normal shape after being deformed by being stretched or compressed

Question 21

Plasticity

Answer 21

ability of a material to be easily shaped or moulded

Question 22

Ductility

Answer 22

ability of a material to resist pulling, be stretched or drawn into sheet or wire.

Question 23

Durability

Answer 23

ability of a material to withstand damage or wear

Question 24

Malleability

Answer 24

ability of a material to change shape when force is applied to it, be deformed without breaking; a malleable material can be hammered into shape.