Physical properties of non-metals - class-VIII

The properties of non-metals are:

Bromine is indeed the only non-metal that exists as a liquid at room temperature under standard conditions.

Iodine is an intensely colored solid with an almost metallic luster. This solid is relatively volatile and it sublimes when heated to form a violet-colored gas.

Chromite is an ore of chromium, bauxite is an ore of aluminium and tungston are metallic in nature while graphite is an allotrope of carbon and a carbonaceous compound. It is a very soft allotrope of carbon while other allotrope of carbon diamond is the hardest known element on this earth. This is because of the chemical structure of graphite which shows slippery nature of layers of carbon and presence of loose electrons.

Graphite is the most stable form of carbon and so it is used as the standard state for defining the heat and formation of carbon compounds. It has a layered planar structure and the bonding between the layers is vander waals bonds. It is a non metal with shining surface.

Non-metals do not have lustre. They do not reflect light from their surface. Non-metals have dull appearance. Diamond and iodine are two exceptions and are lustrous non-metal.

Non-metals do not have luster. They do not reflect light from their surface (exception diamond and iodine). Non-metals have dull appearance.

Silicon is a tetravalent metalloid. Pure silicon is used to produce silicon wafers in the semiconductor industry. Pure silicon is an intrinsic semiconductor as it conducts electron holes and increases electrical conductivity. Silicon is doped with other microelements to increas its conductivity. It is used in transistors, solar cells, semiconductor devices.

Non-metals are malleable, is an incorrect statement.

Bromine is a liquid non-metal. Rest others are metals.

Bromine is the only non-metal which is liquid and diatomic molecule at room temperature. 

Most of the non-metals are bad conductor of heat and electricity. But there are some non-metals which conduct electricity for example graphite. Due to presence of free electron in it.

Non-metals are not dense enough and do not have enough free electrons to pass electricity efficiently. Electrons in non-metals are held tightly , they are no allowed to move freely .

Oxygen is a non-metal. Non-metals do not have enough free electrons to pass electricity. Electrons in non-metals are held tightly, they are not allowed to move freely .

Non-metals vary greatly in appearance. They do not have lustre. As it does not have any free electrons light falling on non-metals does not reflect and hence non-metals are not shiny. Hence, they have a very dull appearance.

Diamond is the hardest substance known to man with a hardness of 10.0. It is brittle sometimes because it grows in diamond shape crystals, sometimes there are tiny cracks or flaws in the diamond and a hard strike against the crack of course will cause the diamond to crack into many pieces. Crystalline materials have planes of variable shear and normal strengths hence, they fail on fracture mechanism. Also, crystalline nature makes them extremely strong at surface resisting scratch.

Non-metals are very brittle and cannot be rolled into wires or pounded into sheets. They break easily when hit by a hammer.

Non-metal are neither malleable nor ductile. Non metals are brittle.

Non-metals are not ductile because they are brittle elements. They break easily. Such non-metals cannot be deformed by a hammer or rolling. 

Selenium is a chemical element with symbol Se and atomic number 34. It is a nonmetal with properties that are intermediate between those of its periodic table column-adjacent chalcogen elements sulfur and tellurium. As it a non-metal, it cannot be deformed into a wire as it is brittle.

Iodine is a non-metal which is brittle in nature, it breaks and shatters easily when hammered. Hence, it cannot be used to make thin wires and is non-ductile.

Non-metals are non-malleable and non-ductile. They are brittle. They break easily. So, they are regarded as brittle. They can't be stretched into mines or hammered into sheets.

Brittleness is a characteristic property of non-metals. And here, we consider solid non-metals only. It is not applicable to liquid or gaseous non-metals.

Non metals do not have  lustre which means that non-metals do not have a shining surface. That means they have a dull appearance.

Non-metals are poor conductor of heat. So, they can't be used for cooking utensils.  

Hydrogen and helium are the two lightest gasses,  they weigh so less that helium balloons and hydrogen dirigibles are able to float in the atmosphere.

Carbon is the non-metal which conduct electricity in the form of graphite which is it's allotrope. Allotropes are the compound of the element in which they have same chemical properties but different physical properties. 

Semiconductors are the elements which conduct electricity but in less quantity. Hence, they are called as semiconductors.

Lustre means shine. Shining metals are also called lustrous metal. For example, gold. Non-metals such as sulphur, oxygen, nitrogen are non-lustrous but iodine is a greyish black solid and crystals have a metallic lustre.

All are metals in the given options iron, aluminium and copper but only carbon is a nonmetal present which is breakable with a hammer.

Non-metals have properties similar to that of metals , This  Statement is false because:

Properties of metals : 

Metals are solid at room temp. 
They are generally hard and strong. 
They have metallic lustre. 
They have high melting and boiling points. 
They are good conductors of heat and eletricity. 
Metals are sonorous. 
Most metals have high tensile strength. 
They are malleable. 
They are ductile. 
They have high densities. 


Properties for non-metals: 

Non-metals are glasses or solids at room temp. except bromine. 
They are not as hard as metals and have low tensile strengths. 
They do not have lusture. 
They are bad conductors of heat and electricity. 
Non-metals are brittle, they are neither malleable nor ductile. 
They usually have low densities. 
They have low melting and boiling points. 
They are non-sonorous. 

Zinc on heating with sulphur produces a greyish residue of zinc sulphide.
Sulphur is an element belonging to VI A group.
Sulphur is a nonmetallic element.

Amorphous or plastic sulfur is produced by rapid cooling of molten sulfur e.g. by pouring it in cold water. It has helical form and metastable at room temperature reverting to its crystal allotrope and have sharp melting point.

In case of iodine, the large size of the atom results in low shielding of valence electrons. 

Metals have high melting and boiling point. Tungsten has the highest melting point where as silver has low boiling point. Sodium and potassium have low melting points. Non metals have low melting point.

Graphite is able to conduct electricity, due to delocalization of the pi bond electrons above and below the planes of the carbon atoms. These electrons are free to move, so are able to conduct electricity.
In diamond, all four outer electrons of each carbon atom are 'localized' between the atoms in covalent bonding. The movement of electrons is restricted and diamond does not conduct an electric current.
Thus, graphite is a good conductor and diamond is not. 
Option "B" is correct.

Diamond and graphite are allotropes of carbon. Graphite has carbon molecules held together by weak van der Waal's forces of attraction and they have loosely bound electrons which are responsible for conducting electricity, while diamond is the hardest and strongest material in which all the molecules are bound by strong bonding between carbon tetrahedrons held by strong forces of attraction and so, they do not have free or loosely bound electrons to conduct electricity.

It's because going down the group the size of the atom increases because of the shielding effect due to which the interaction between the atom and the outermost electron decreases.

 So these electrons on the surface of iodine become excited by absorbing heat energy from light. so when they release this energy and come to their normal state, they emit this light so it appears that they have a shining surface.

So, the correct option is $C$

At room temperature liquid non-metal is bromine.

Graphite has a layered planar structure. Carbon atoms in the plane are bonded covalently with only three of the four potential bonding sites. The fourth electron is free to migrate in the plane making graphite electrically conductive.

Sulphur is a non-metal so it does not conduct electricity. Iron is a metal so it conducts electricity Magnesium oxide and Lithium fluoride are ionic compounds that contains ions which conducts electricity in molten state.

Its because going down the group the size of the atom increases because of shielding effect due to which the interaction between the atom and the outermost electron decreases so these electrons on the surface of iodine become excited by absorbing heat energy from light so when they release this energy and come to their normal state, they emit this light so it appears that they have lustrous surface.

1) Graphite is soft and slippery because there are only weak intermolecular forces between its layers. Graphite is a good conductor of heat and electricity.

2) Graphite can conduct electricity because of the delocalised (free) electrons in its structure.

3) These arise because each carbon atom is only bonded to 3 other carbon atomsHowever, in diamond, all 4 outer electrons on each carbon atom are used in covalent bonding, so there are no delocalised electrons.

4) These electrons in graphite are free to move through the structure.

It is a pale green gas and is used in cleaning products. Chlorine is an greenish-yellow gaseous element. Its atomic number is 17, and is one of the class called halogens in the periodic table. Large concentration of chlorine are dangerous.

Answer: all of the above 

Non-metals are non-malleable, non-ductile when they are beaten with hammer or stretched they break into pieces, so they are brittle.

When sulphur or phosphorus is stretched, they break into pieces. Non metals are non-malleable non-ductile.

Most of the solid non-metals are quite soft. For example - sulphur and phosphorous are solid non-metals which are quite soft.

Diamond and iodine both are non metal and lustrous.

Carbon is a non-metal which have allotropic form that is graphite, diamond and fullerene. Out of this three only graphite is conductor of electricity. Diamond and fullerene do not conduct electricity.

The basic difference between metals and non-metals is the extent of bonding.Metals have very high extent of bonding than that in non-metals which makes the metal malleable. and non-metals brittle.

Non-metals are generally non-ductile and cannot be beaten into thin wires. All given elements $O,P,S$ are non metals and do not have property of ductility. 

Mercury and bromine both are present in liquid state at room temperature but mercury is metal and bromine is non-metal.

Sulphur extracted from natural sources is called brimstone.