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Why are noble gases so unreactive?

Noble gases are unreactive non-metal gases that often show trends in their physical properties, and their uses depend upon their low density, inertness, and non-inflammability.

Let us get acquainted with everything you need to know about noble gases and the reason behind the query.

What are noble gases?

Noble gases refer to the chemical elements in periodic table’s group 18.

The noble gases are most stable because of the maximum number of valence electrons in their outermost shell. And that is why they rarely react with other elements as they are already stable.

 

Chemical properties of Noble Gases

As compared to the other elements on the periodic table, noble gases are inert and highly unreactive.

 

Uses and properties of noble gases

The primary properties of the noble gases include

  • Lower densities
  • Inert
  • Not flammable

 

Uses of Noble gases

  • Helium

Helium is utilized as a lifting gas in airships and party balloons.

  • It’s non-flammable, so it cannot be set on fire.
  • It’s less dense than air do the airships and balloons rise

 

  • Argon

Argon is often utilized as a shielding gas while welding the metal pieces together.

  • It is denser than air, so it prevents the air from getting into the metal
  • It’s inert so that hot metal cannot spoil the weld and oxidize it.

 

So why are noble gases unreactive?

Noble gases are so unreactive because of the number of electrons present in the outermost shell of their atoms. And as their outer shell is full, indicating it is complicated for them to take or give electrons.

As the noble gases enclose an entire valence shell of electrons and due to this configuration, they are

  • Difficult to oxidize as the valence electrons are firmly held by nuclear charge.
  • Difficult to diminish as the electrons must enter the next valence shell.

 

Understanding with explanation!

Noble gases’ outer shell of the valence electrons is generally considered full, giving them a slight tendency to participate in chemical reactions.

The boiling and melting points for a noble gas are close together, differing by less than 18 degrees Fahrenheit or 10 degrees Celsius, including the liquids over a smaller temperature range.

The noble gases generally show significantly lower chemical reactivity, and as an outcome, only a few hundred noble gases compounds are formed.

Neutral compounds in which neon and helium are included in the chemical bonding have not been formed. On the contrary, the krypton, argon, and xenon show minor reactivity only.

Therefore, the reactivity follows the order

Ne < He < Ar < Kr < Xe < Rn

Bottom Line!

Noble gases are considered so unreactive as they have a fully filled outermost orbital configuration, and because of which noble gases are very much stable and have minimum energy.

 

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Explain the molecular structure of CH4

Methane is a gas consisting of one carbon atom for every four hydrogen atoms. Let us get acquainted with everything you need to know about the molecule structure of CH4.

What is Methane?

Methane is a gas comprising Carbon and hydrogen atoms with the chemical formula CH4.

What is Methane

It is found in small quantities in the atmosphere of the earth. It is defined as the simplest hydrocarbon comprising four hydrogen atoms and one carbon atom.

It is a powerful greenhouse gas that is flammable and is often used as fuel worldwide. It is primarily used to make light and heat.

 

Molecular Structure of Methane

The central carbon atom in the CH4 forms the covalent bond with these four hydrogen atoms, and this sharing generally completes the outer shell of both hydrogen and carbon atoms.

The four hydrogens around the central carbon indicate that there are a total of four electron groups around this carbon atom, generating a molecule’s tetrahedral shape.

These tetrahedral-shaped molecules form the 109 degrees’ bond angles.

 

Structure of Methane

Methane has a tetrahedral structure comprising four equivalent C-H bonds.

The shape of methane is a regular tetrahedron with carbon at the centre and hydrogen at each corner.

Structure of Methane

Each H-C-H in methane has an angle of 109.5°, and every CH bond distance is at 1.09 angstroms.

 

Is CH4 polar or nonpolar?

The methane structure has all the outer atoms the same, that is, it includes the same dipoles, and also the dipole moments are also in the same direction.

The dipole moment is towards the carbon atoms, so the overall molecule becomes non-polar.

Therefore methane has non-polar bonds and is considered non-polar overall.

 

Why is CH4 tetrahedral in shape?

Methane is considered tetrahedral in shape as it has 4 electron density regions around the central carbon atoms having four bonds and no lone pairs.

Why is CH4 tetrahedral in shape

And therefore, the resulting shape comes as a regular tetrahedron with H-C-H angles of 109.5°.

 

Why is the CH4 molecule tetrahedral?

CH4 molecule is tetrahedral as the four C-H bonds in methane are held at an angle of 109 degrees – 28’.

Since the angle in the space at which the repulsions between the four shared electrons pairs is minimum.

 

Uses of CH4

Methane is used

  • In oven, automobiles and water heater
  • In electricity generation
  • As a rocket fuel
  • To sanitize the products
  • As an antifreeze ingredient
  • In gas-fired power stations
  • In the gas appliances testing
  • In gas cookers

 

Bottom Line!

Methane has a tetrahedral molecular structure with carbon at the centre and hydrogen at each corner. We hope this answer has given you clarity over the molecular structure of CH4.

 

 

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What is the overall charge of the nucleus of an atom, and why?

An atom comprises a tiny nucleus surrounded by moving electrons. And nucleus is basically a collection of neutrons and protons where

  • Neutrons are electrically neutral
  • And Protons are positively charged

 

So, what is the overall charge of the nucleus of an atom?

A nucleus is consists of the neutrons and protons where

  • Neutrons have a neutral charge
  • And Protons have a positive charge

A neutral charge won’t cancel out the positive charge that indicates that the overall charge of a nucleus is positive.

 

And why is the overall charge of a nucleus Positive?

The neutrons present in the nucleus have a neutral charge, whereas the protons in the nucleus have a positive charge. As neutral won’t cancel out the positive charge, so the overall charge of the nucleus is positive.

 

What determines the positive charge of the nucleus?

The number of protons present in the nucleus determines the positive charge of the nucleus.

As the protons are positively charged, and a nucleus comprises protons and neutrons, so the protons present in the nucleus determine the positive charge.

Even though the nucleus contains neutrons also, they do not impact the charge as they have no charge, and therefore they do not contribute to the nucleus charge.

 

Bottom Line!

A combination of neutral particles and positively charged particles definitely forms a positively charged particle only.

Therefore, a nucleus has an overall positive charge.

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Explain what occurs when an acid reacts with an alkali in terms of ions and molecules. Also, show the equation.

When an acid reacts with an alkali, a chemical reaction happens and the formation of a new substance takes place.

Let us get acquainted with everything you need to know about the query.

  • What happens when you react acid with Alkali?

Whenever you add acid with Alkali, a chemical reaction takes place, and a new substance is formed.

If you mix the exact amounts of acid with Alkali, you will end up with a neutral solution which is also known as a neutralization reaction.

  • What exactly is it called when an acid reacts with Alkali?

An acid reaction with Alkali or, say, an acid-alkali neutralization refers to a reaction between the hydroxide and hydrogen ions forming water.

  • Whenever an acid and Alkali are mixed, what sort of reaction takes place?

Whenever the acid and Alkali are mixed, a neutralization reaction takes place, forming salt and water.

A neutralization reaction is always

Acid + Alkali ——> Salt + Water

Equation of acid reacting with Alkali

H+ + OH- —> H20

However, here the question is about ions, and there is no salt. So, the acids are H+ ions that give them the desired acidic properties, and alkalis are the OH- ions. And together, they react to form water.

Essential to Remember!

  • Alkalis in the solution are the sources of Hydroxide ions represented by OH-
  • And Acids in the solution are the sources of Hydrogen ions represented by H+.

And so the reaction is represented as

H+ (aq) + OH- (aq) → H2O (l)

 

Bottom Line!

When it comes to checking the reaction of an acid with alkalis in terms of ions and molecules, the Hydrogen ions from the acid react with the hydroxide ions from alkalis to form water.

And the reaction is represented as

H+ (aq) + OH- (aq) → H2O (l)

 

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Describe the differences between the three types of bonding

The three types of bondings are namely

  • Ionic Bonding
  • Covalent bonding
  • Metallic Bonding

Let us get acquainted with all the essential information concerning all three types of bondings.

What is ionic bonding?

Ionic bonding is the one that takes place between metals and non-metal atoms.

This type of bonding generally involves the electrons transfer from metal to non-metals developing a negatively charged non-metal ion and a positively charged metal ion.

For instance, Na+ and Cl- making NaCl.

These are more like the blood donations where a metal atom gives its electrons to a non-metal atom.

Since the electrons are negatively charged, that means the metals become more positive while the non-metals become more negative. Just like south and north on a magnet!

 

What is covalent bonding?

Covalent bonding takes place between the non-metal atoms only. Here instead of the electrons transfer taking place in the ionic bonding, this type of bonding includes the electrons sharing between the non-metal atoms.

For instance, H+ and OH- make H2O.

Covalent bonds are the ones where two atoms share their electrons. The orbitals that electrons sit in overlie between one atom and the next. This satisfies both the atoms and makes them stable.

Some of the two non-metal atoms that cannot even easily move away from each other are more like the blood brothers.

 

What is metallic bonding?

Metallic bonding is the one that is different from other types of bonding as it occurs between metal atoms only.

Here the metal atoms are arranged in a regular pattern in which the electrons in the outermost shell are delocalized and form solid metallic bonds.

For instance, Metals like iron, zinc, etc.

Here the extra electrons present in the metal atoms are dropped, making the metal a positive ion.

And the extra electrons become an electrons sea that is negative, so the positive metals stick to the negative electrons while forming a large metallic lattice structure.

 

Understanding the differences between the three types of bonding

Parameters Ionic Bond Covalent Bond Metallic Bond
Occurrence It occurs during the electrons transfer It takes place when two electrons share their valence electrons. It takes place during the attraction of metal atoms/ cations and delocalized electrons
Binding Energy Here the binding energy is higher than the metallic bond. Here the binding energy is higher than the metallic bond Here the binding energy is lower than the ionic and covalent bond
Bonds Non Directional bonds Directional bonds Non-directional bonds
Conductivity It has Low Conductivity It has a Very Low Conductivity It has a higher electrical conductivity/
Molding property It is unmoldable It is unmoldable It is moldable
States It is present in only one state that is the solid state It is present in all three states including the solids, liquids, and gases It is present in only one state that is the solid state
Ductile property It is non-ductile It is non-ductile It is ductile
Melting Point It has a higher melting point It has a lower melting point It has a higher melting point
Boiling point It has a higher boiling point It has a lower boiling point It has a higher boiling point

 

Bottom Line!

The major differences between all three bonds can be summed up like

  • Ionic bonds are formed due to the electron transforming from one atom to another.
  • The electron sharing between two atoms forms covalent bonds.
  • Metallic bonds are formed between the metal atoms and valence electrons.

 

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Describe why diamond is hard and Graphite is soft?

Even though Graphite and diamond are made of carbon, the diamond is hard, whereas the Graphite is soft.

This is due to the strong covalent bond among its atoms forming a regular tetrahedron that is difficult to break.

On the contrary, the Graphite comprises of a flat hexagonal ring forming the carbon atoms layers. The several layers of carbon atoms are so far away from each other that covalent bond formation cannot even exist.

These carbon atom layers are held together by the weak van der Waals forces, allowing them to slide over each other.

And because of this layered structure of carbon atoms, Graphite is stronger than diamond.

Take a rotating graphic of graphite molecules and a diamond structure and try this to understand the reason.

 

  • For Graphite

Rotate the graphite molecule. As the Graphite is layered, and there are strong covalent bonds between the carbon atoms present in each layer, only weak forces exist between layers. This permits the carbon layers to slide over each other.

  • For Diamond

Rotate the structure of the diamond, and do not forget that each diamond atom is at the same distance from each of its neighbouring carbon atoms.

There exists a rigid bonds network within the diamond crystal. And in this rigid network, the atoms cannot even move, which is why diamonds are hard.

Bottom Line!

Diamond has a 3-dimensional strong covalent bonds network, and it is very complicated to break the extended covalent bonding. And that is why the diamond is considered the hardest substance.

On the contrary, Graphite has layered structures that are held together by weak Vander Was forces. Therefore, Graphite cleaves easily between these layers, which is why they are soft and slippery.

 

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