Solid materials that can undergo substantial plastic deformation prior to fracture are called ductile materials. Solid materials that exhibit negligible plastic deformation are called brittle materials. Brittle materials fail by sudden fracture (without any warning such as necking).

18.2. 1 Modes of fracture There are two types of fracture: brittle fracture and ductile fracture. Brittle fracture involves crack growth with little or no ductile deformation of the material around the crack tip. As a result, ductile fracture is the preferred failure mode for damage-tolerant materials.

Fracture involves the forced separation of a material into two or more parts. Brittle Fracture involves fracture without any appreciable plastic deformation (i.e. energy absorption). Ductile Fracture in the converse and involves large plastic deformation before separation.

francium

A nonmetal is an element that is generally a poor conductor of heat and electricity. In the solid state, nonmetals are brittle , meaning that they will shatter if struck with a hammer. The solids are not lustrous. Melting points are generally much lower than those of metals….

Silicon

The Non-Metal elements are:

• Hydrogen.
• Carbon.
• Nitrogen.
• Oxygen.
• Phosphorus.
• Sulfur.
• Selenium.

Helium (He) is the first of the Noble Gases. Just like neon (Ne) and argon (Ar), helium just floats around all by itself. It is non-reactive because it’s shell is full. Helium only has one atomic shell, which fills up when it has two electrons.

What Are Noble Gases? Noble gases are nonreactive, nonmetallic elements in group 18 of the periodic table. As you can see in the periodic table below, noble gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). All noble gases are colorless and odorless….

“They found that if you put sodium and helium together and compress it to pressures like at the center of the Earth, sodium can actually react with helium and form stable compounds.” At first some scientists thought helium might be sharing electrons after all….

Neon gas

Xe

Revision notes on the topic ‘Group 7: Reactivity’ for Edexcel IGCSE Chemistry

• Reactivity of Group 7 non-metals increases as you go up the group.
• Out of the 3 halogens, chlorine, bromine and Iodine, chlorine is the most reactive and iodine is the least reactive.

Reactivity decreases down the group. This is because group 7 elements react by gaining an electron. As you move down the group, the amount of electron shielding increases, meaning that the electron is less attracted to the nucleus.

Noble gases

Sodium and chlorine react vigorously when heated, giving an orange flame and clouds of white sodium chloride. The halogens become less reactive going down group 7….Reactions with metals.