NEET Study Notes for P- block elements: In P-Block elements, there are six groups from the number 13 to 18- Boron, Carbon, Nitrogen, Oxygen, Fluorine, and Helium family. In these elements, the last electrons enters the p-orbital. Each p- orbital can accommodate two electrons as the number of p-orbitals is 3. The total number of electrons that can be accommodated is six. Due to their tendency to lose electrons. P-block elements are generally good conductors of heat and electricity.

• In NEET Chemistry Syllabus. P-block elements are a part of Class 11th and Class 12th syllabus. With a weightage of 34% of Inorganic Chemistry, candidates can expect at least 2-3 questions.
• In order to prepare for NEET 2022, NEET Study Notes for P-block elements will help you in understanding the physical and chemical properties of Group 15, Group 16, Group 17, and Group 18.

Quick Links:

NEET Study Notes on P-Block Elements

Group 15 Elements - Nitrogen Group

Group 15 of periodic table consists of nitrogen, phosphorus, arsenic, antimony and bismuth. These are also known as nitrogen group elements. The trends in group 15 elements are

• Electronic Configuration- Generally the electronic configuration of Group 15 elements.
• The valence electronic configuration of all elements is the same as they are of the same group.
• P- block elements are stable a sp- orbital is half-filled by electrons, however, the s-orbital is always occupied.

Atomic Radii

Atomic Radii, as well as ionic radii, increase with an increase in atomic number. However, in arsenic and bismuth, it does not increase with much extent due to d and f orbital addition.

Ionization Enthalpy

The amount of energy required to liberate an electron from outermost orbitals, is known as the Ionization Enthalpy of the atom. The electrons of elements with smaller radii are tightly held by the nuclei. This requires large energy to liberate the electron.

Electronegativity

An atoms tendency to attract electrons is termed electronegativity. Due to the increase of atomic radius, electronegativity decreases as we down the group.

Physical Properties

• The metallic characteristics of Group 15 elements increases, down the group. Nitrogen and Phosphorous are non-metals while Arsenic and Antimony are metalloids.
• Group 15 elements are polyatomic.
• Down the group, atomic size increases.
• Except for Nitrogen, all elements have their allotropes.
• The boiling point of elements increases down the group.
• Nitrogen is a gas and liquifies at -200C, freezes at -210 C. Bismuth is solid and liquefies at 271 C and the boiling point is 156 C.
• Nitrogen is a colourless gas, The colour of phosphorus is red or violet. Bismuth is a silver-white metal while Antimony is a silver element.

Must Read:

• NEET Study Notes for Aldehydes, Ketones and Carboxylic Acid
• NEET Study Notes on Hydrogen

Chemical Properties

• Electronic configuration of the valence cell of Group 15 elements is ns²np³
• These elements can accept 3 electrons or lose 5 electrons.
• Oxidation states of Group 15 elements are +5,+3 and -3.
• The ability to form -3 oxidation state decreases due to the decreasing electronegativity, ionization enthalpy and increasing atomic radius.
• Due to the effect of the inert pair, the tendency of obtaining a +5 oxidation state also decreases.

Group 16 elements- Oxygen Group

Group 16 elements consist of oxygen, selenium, tellurium and polonium. These elements are also known as Chalcogen which means ore formation.

• Occurrence of the elements- The most abundant element is oxygen in Group 16 elements. Oxygen present in dry air makes up about 21.0% of its composition.
• Sulphur occurs mainly in combined forms like gypsum, sulphates, Ipsum salt, baryte and sulphides like zinc blende, copper pyrites A small amount of Sulphur is also present in meteorites and volcanoes in the form of Hydrogen Sulphide. Some natural substances like mustard, eggs, onions also contain sulphur.
• Selenium and tellurium can be found as selenides and tellurides in sulphide ores. Thorium and Uranium minerals on decaying, give rise to a radioactive called Polonium.

Electronic Configuration

• Electronic Configuration of the valence shell of group 16 elements is ns²np⁴.
• The numbers of electrons present are 6- valence shell, 2- s shell, 4- p subshell.
• In the p-subshell, four electrons are present, two of these are paired while 2 are not. The elements have two fewer electrons in order to achieve the near noble gas electronic configuration.

Atomic Radii

In comparison to Group 15 elements, the atomic radii of Group 16 elements is small. The atomic radii increase as we move down the group due to an increase in atomic number or the number of shells.

Electronegativity

Group 16 elements consist of the second most electronegative element- Oxygen. The electronegativity decreases as we move down the group from Oxygen to Polonium Due to an increase in atomic size, nuclear charge decreases due to which the electronegativity decreases.

Also Read NEET Study Notes on Classification of Elements

Melting Point and Boiling Point

The melting and boiling point increases down the group. However, due to the inert pair effect, the melting and boiling point of polonium is less. An increase in the melting and boiling point of other elements is due to an increase in Van der Waals force and atomic size.

Ionization Enthalpy

Ionization enthalpy decreases down the group due to repelling force of electrons by the addition of new electrons in the np3 shell. However, in comparison to group 16, the I.E of group 16 elements is high.

Electron Gain Enthalpy

Electron Gain Enthalpy decreases down the group. Due to the compressed nature of oxygen, its electron gain enthalpy is less than sulfur. Due to the increase in atomic size, the electron gain enthalpy becomes negative as we move down the group.

Physical Properties of Group 16 elements

• Non-metals in group 16 are oxygen and sulphur. Metalloids are Selenium and tellurium.
• Polonium is a radioactive element.
• All elements of Group 16 have their own allotropes. The allotropes of Oxygen are- Oxygen and Ozone. The two stable allotropes of Sulphur are Rhombic and Monoclinic Sulphur. Selenium and Tellurium can be found in crystalline and amorphous forms.
• The melting and boiling points increase down the group with an increase in atomic size.

Chemical Properties of Group 16 elements

• Reaction with Hydrogen- These elements react with hydrogen to form Hydrides These could be H₂E

where E could be any of the Group 16 elements- oxygen, sulfur, selenium, tellurium, and Polonium.

• Reaction with Oxygen - These elements react with oxygen to form oxides of type EO₃, EO₂These oxides, sulfur dioxide, and oxygen exist as gases while selenium dioxide exists as a solid.

• Reactivity towards Halogen- On reaction with Halogen, Hydrides of type EX₆, EX₄, EX₂ are formed.

where E is the lament of Group 16

X is a halogen

Group 17 elements- Fluorine Group

Elements of group 17 include- Fluorine, Chlorine, Bromine, Iodine, and Astatine. These are known as halogens as they produce salts reacting with metal These are highly reactive and highly electronegative elements.

Electronic Configuration

General Electronic Configuration for Group 17 elements is ns²np⁵, which means there is number of electrons in the outermost shell is 7. One more electron is required for these electrons to attain the nearest noble gas configuration. Thus these elements have a tendency to either gain one electron to form an ionic bond or lose an electron to form a covalent bond.

Atomic Radii

The atomic radii of Group 17 elements increases as we move down the group. However, they have the smallest atomic size in comparison with other similar elements. This is due to their high atomic charge.

Electronegativity

The electronegativity decreases down the group from Fluorine to Iodine, due to energy levels which lead to less attraction between the nucleus and electrons. However, halogens have high electronegativity. The electronegativity order of Group 17 elements is

Read More Best Android Apps for NEET 2022 Preparation

Ionization Enthalpy

Ionization Enthalpy decreases down the group. However, these elements have high ionization enthalpy. I.E. of Group 17 elements reduces due to increasing in nucleus radii. The highest I.E amongst Halogens is of Fluroirne.

Electron Gain Enthalpy

Electron gain enthalpy of Halogens are Negative. However, it becomes less negative down the group. The electron gain enthalpy of Fluorine is less in comparison to chlorine due to its small size.

Physical Properties of Halogens

• Physical State- These elements exist in all states- Solid, Liquid, and Gas. While fluorine and Chlorine exist as a gas, Bromine is liquid and Astatine oxides exist as a solid substance.
• Color- Halogens derive their color from the absorption of light by the molecules. Fluorine has a yellow pale color, chlorine is pale green, Iodine is violet, bromine is reddish-brown, and astatine is black metallic.
• Solubility- Chlorine, and Florine are soluble in water but Iodine and Bromine are less soluble.
• Melting and Boiling Point- Melting and Boiling point of these elements increases down the group from Fluorine to Iodine. Thus Fluorine has the lowest melting and boiling points while Iodine has the highest.

Must Read:

• NEET Study Notes on Hydrogen
• NEET Study Notes on Structure of Atom

Chemical Properties of Halogens

• Oxidising Power- Due to high electron affinity, halogens are good oxidizing agents. The most powerful oxidizing agent of these elements is Fluorine. It can oxidize all halide particles. This particle also acts as a reducing agent and their reducing capacity decreases as we move down the group. Oxidizing capacity also reduces the group.

• Reaction with Hydrogen - Hydrogen halides are formed on the reaction of halogens with hydrogen. These are acidic in nature. The acidity diminishes down the group. HI is the least acidic. Fluorine reacts violently with hydrogen. Bromine reacts in heating and iodine requires a catalyst. Chlorine reacts in the presence of sunlight.

• Reaction with Metals- Halogens are highly reactive so they react with metals to form metal halides. Due to the high electronegativity of halogens, metal halides are ionic. The ionic tendency of these diminishes from Fluorine to Iodine.

Example- Sodium and Chlorine gas reaction forms Sodium Chloride, Heat energy, yellow light is produced is due to exothermic reaction

• Reaction with Oxygen - Halogen and Oxygen react to form Oxides. Halogens also produce oxoacids by reacting with compounds that contain Hydrogen and Oxygen. Examples- are hypochlorous acid, chlorous acid, chloric acid.

Read NEET Study Notes for Properties of Bulk Matter

Group 18 elements - Noble Gases

Group 18 elements consist of Helium, Neon, Argon, Krypton, Xenon, and radon. These are known as noble gases or inert gases. As they have completely filled electronic configuration and don't take part in any chemical reaction. These elements exist in a free state in the atmosphere except Radon.

Electronic Configuration of Group 18 elements

General electronic configuration of group 18 elements is except helium which has an electronic configuration of 1s2. These elements have eight electrons in the outermost shell. They have a stable octet configuration.

Atomic Radii

The atomic radii of noble gases increases with an increase in atomic number down the group. These elements however have small atomic radii.

Ionization Enthalpy

I.E decreases down the group however they have high I.E due to the stable octet configuration and duplet configuration of helium.

Electron Gain Enthalpy

They do not accept electrons as they have stable electron configurations.

Physical Properties of Group 18 elements

• These are found as monatomic gases due to their stable configuration.
• These gases are colorless, tasteless, and odorless.
• Due to the weak Van der Waals force, melting and boiling point is low.
• These gases can be condensed at extremely low temperatures. However, with an increase in atomic size, there is also an ease of liquefaction.

Uses of Group 18 Elements

NEET MCQs for P-Block Elements

Question: What is the number of groups present in p-block elements?

1. 5
2. 4
3. 6
4. 3

Answer: 6- Boron, Carbon, Nitrogen, Oxygen, Fluorine and Helium

Question: Which of the following element group is called Chalcogens?

1. Helium, Neon, Argon, Kryptonite
2. Nitrogen, Phosphorous, Arsenic, Antimony
3. Fluorine, Chlorine, Bromine, Iodine
4. Oxygen, Sulphur, Selenium, Tellurium

Answer: Oxygen, Sulphur, Selenium, Tellurium

Question: Which element will not form a stable diatomic molecule?

1. Oxygen
2. Iodine
3. Nitrogen
4. Phosphorous

Answer: Phosphorous

Question: The structure of Graphite is similar to—-?

1. B2H6
2. B4C
3. B
4. BN

Answer: BN

Question: Name the most stable oxoacid of chlorine?

1. HCIO3
2. HCIO4
3. HCIO2
4. HCIO

Answer: HCIO4

Quick Links: