Physical and chemical properties of elements

In chemistry, learning about atomic and molecular structures, chemical bonding, and synthesis helps us understand the elements around us. We look at physical properties like density, state at room temperature, melting and boiling points, and conductivity—these describe how a substance behaves without changing its identity.

Then there are chemical properties, which explain how a substance can change into something new. This includes reactivity, acidity or basicity, flammability, and corrosion. For example, alkali metals react easily with water, while noble gases stay mostly unreactive because of their full electron shells.

Knowing both physical and chemical traits lets scientists predict reactions and design processes like drug production, material creation, and pollution treatment . Understanding these properties not only helps identify substances but also drives the development of new materials, medicines, and environmentally friendly solutions.

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In this article, we will be focussing on the in-depth knowledge of the important topic of physical and chemical properties of the elements, which is the sub-topic of the chapter Classification of Elements and Periodic Table from class 11 chemistry. It is not only essential for board exams but also for competitive exams like the Joint Entrance Examination (JEE Main), National Eligibility Entrance Test (NEET), and other entrance exams such as SRMJEE, BITSAT, WBJEE, BCECE, and more. Over the last ten years of the JEE exam (from 2013 to 2023).

Let's discuss Element's physical and chemical properties in detail to gain some insight in a joyful manner to solve some related problems on the same.

Exploring Physical and Chemical Properties

There are various factors on which the physical and chemical properties of the elements depend, let us discuss each point in detail.

Atomic Volume

In moving from left to right in a period the atomic volume first decreases and then increases because of the following reasons:

• As we move in a period from left to right, first the increase in nuclear charge overcomes the increase in the number of electrons. Thus, the atomic volume decreases.

• But on moving further in a period, newly added electrons enter into the p orbitals and because of the high shielding power of s and p orbitals, atomic volume increases.

In moving from top to bottom in a group, the atomic volume increases due to the increase in the number of shells.

Density

The density of elements also follows almost the same order as the atomic volume. In moving from left to right in a period, the density increases first and becomes maximum till some middle elements thereafter it starts decreasing gradually.

Melting Points and Boiling Points

The melting points of elements show a general trend with their atomic numbers. The elements with low atomic numbers have high melting points while the elements with higher atomic numbers have low melting points. In a period from left to right, the melting points of elements first increase and become maximum till some middle elements and then it decreases gradually.

Value of melting point of elements-

The boiling points of elements also show similar trends as the melting points but the trend is not that much regular.

In moving down the group, melting and boiling points follow the regular trend but the trend is different for different groups. For example for the alkali group, the melting and boiling points decrease in moving from top to bottom but for halogens, the melting and boiling points increase in moving down the group.

Also Read:

• Atomic Size & Atomic Radius
• Electron Gain Enthalpy
• Electronegativity

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Solved Examples Based On- Atomic Volume

Example 1: The atomic radius of elements of which of these would be nearly the same?

1) Na, K, Rb, Cs

2) F, Cl, Br, I

3) Li, Be, B, C

4) Fe, Co, Ni, Cu

Solution: As we have learned, the Physical Properties of Elements - Atomic radii of transition elements remain almost the same in the period. Therefore, Fe, Co, Ni, and Cu have nearly the same atomic radii.

Hence, the answer is the option (4).

Example 2: Among the following which has the maximum density?

1) Phosphorous

2) Sulphur

3) Silicon

4) Aluminium

Solution: Density

Value of density(in g/cm³) of given elements:-

1) Phosphorous - 1.823
2) Sulphur - 2.06
3) Silicon - 2.34
4) Aluminium - 2.70

2.70 is greater than others, so Al has the maximum density among given elements.

Hence, the answer is the option (4).

Example 3:Which of the following has the maximum density?

1) Sulphur

2) Phosphorus

3) Aluminium

4) Silicon

Solution: Properties of Elements -

Density, Metals have a higher density than metalloids and metalloids have a higher density than non-metals.

Hence, the answer is the option (3).

Example 4: Which of the following is arranged in order of increasing density?

1) Al < Mg < C(graphite) <B

2) Al > Mg > C(graphite) >B

3) Mg < C(graphite) <B <Al

4) Mg > C(graphite) > B > Al

Solution: Physical Properties of Elements -Density Density increases from left to right up to the middle in a period and increases down the group in the periodic table. Graphite is a less dense form of carbon thus the order of density is:

Mg < C(graphite) <B <Al

Hence, the answer is the option (3).

Example 6:Which of the following has the lowest melting point?

1) Mg

2) Be

3) Ca

4) Sr

Solution: The melting point of elements shows a general trend with their atomic numbers. The elements with low atomic numbers have high melting points while the elements with higher atomic numbers have low melting points. In a period from left to right, the melting points of elements first increase and become maximum till some middle. The melting point of elements decreases down the group because in moving down the group, the size of elements increases, and thus the metallic bond between the atoms becomes weaker, and hence the melting point decreases.

Hence, the answer is the option (4).

Example 7:What happens to the conductivity of metal when temperature is increased?

1) It decreases

2) Remains constant

3) It increases

4) None of these

Solution: As we have learned, the Effect of temperature on conductivity -

The conductivity of the metal decreases with the temperature rise. This is because with the temperature rise the positively charged kernels also, start vibrating which interferes with the movement of electrons.

As the temperature increases the molecular vibration also increases which obstructs the flow of free electrons, thus conductance decreases.

Hence, the answer is the option (1).

Example 8 The reason for good thermal conductance of metal is:

1) Transport of energy

2) Free electrons and frequent collision of atoms

3) Lattice defects

4) Capacity to absorb energy

Solution: As we have learned Thermal conductivity of metals - On heating a part of the metal, the kinetic energy of the electron in that region increases. The energised electron moves rapidly to the cooler part and gives its excess kinetic energy to other electrons in the cooler part of the metal. Thus heat is conducted through metal.

For good conductors, there must be free electrons present in the metal.

Hence, the answer is the option (2).

Practice More Questions From the Link Given Below:

Conclusion

Understanding physical and chemical properties of elements is vital for connecting matter’s behavior to real-world applications. Physical properties—like density, melting and boiling points, conductivity—help tailor materials for industries such as electronics, metallurgy, and technology design. Meanwhile, chemical properties—reactivity, bonding potential, catalytic activity—explain how substances interact and transform, enabling creation of new compounds. For example, transition metals act as catalysts in industrial processes, and halogens readily form acids . Together, these insights allow chemists to predict reactions, engineer advanced materials, develop medicines, and address challenges like pollution and renewable energy—laying the groundwork for ongoing innovation and understanding in science.

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NCERT Chemistry Notes:

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