Problem 134 - A Complete Resource Book in Chemistry for JEE Main

Question

An element with atomic number 34 belongs to which period?

Step-by-Step Solution

Answer

The element belongs to the 4th period.

Step 1: Identify the Atomic Number

The atomic number of the element provided is 34. This is a key piece of information as it will help us locate which period the element belongs to in the periodic table.

Step 2: Locate Element on Periodic Table

Using the atomic number 34, identify the element on the periodic table. Atomic number 34 corresponds to the element Selenium (Se).

Step 3: Determine the Element's Period

Look at the position of Selenium (Se) in the periodic table. Selenium is located in the 4th row, which corresponds to the 4th period.

Key Concepts

Atomic Number

The atomic number of an element is a fundamental property that defines the identity of an element. It indicates the number of protons that are present in the nucleus of an atom. For example, when we refer to the atomic number 34, it tells us that any element with this atomic number contains 34 protons in its nucleus. Atomic numbers are unique to each element and are used to distinguish one element from another. They are listed sequentially in the periodic table, allowing us to easily identify the corresponding element by its atomic number.

Element Location

To locate an element using its atomic number, simply refer to the periodic table. The periodic table is systematically arranged such that each element is placed in increasing order of atomic numbers from left to right. When you look at atomic number 34, by following this method, you will find the element Selenium (Se). The periodic table is a powerful tool for quickly identifying elements based on their atomic numbers and for learning about their other properties due to its organization by groups and periods.

Period Determination

The concept of periods in the periodic table is crucial for understanding how elements are grouped. A period is a horizontal row within the periodic table, and it reveals the number of electron shells in the atoms of the elements within that row. For Selenium (Se), which we located at atomic number 34, it is situated in the 4th period. This means that Selenium has four electron shells. Identifying the period to which an element belongs helps in predicting its chemical and physical properties.

Selenium

Selenium, with the symbol Se, is a non-metal element with an atomic number of 34. It is known for its important role in biological systems and is a vital trace element in the diet. Selenium is positioned in the 4th period of the periodic table, which indicates it has four electron shells, and it is part of group 16, which is also known as the chalcogens. This group includes other well-known elements like oxygen and sulfur. Selenium's unique properties make it useful in various applications such as electronics, glass production, and in the formulation of certain vitamins and enzymes essential for health.