Question

Which element has the atomic number 1? A) Helium B) Hydrogen C) Lithium D) Boron

Answer 1

Answer: B) Hydrogen

Explanation:

The correct answer is B) Hydrogen because hydrogen is the first element on the periodic table with atomic number 1. The atomic number represents the number of protons present in the nucleus of an atom, which is unique for each element.

Hydrogen is the simplest and lightest element in the universe. It consists of just one proton in its nucleus and one electron orbiting around it. Since the atomic number is defined as the number of protons, hydrogen naturally gets the atomic number 1.

Let's look at why the other options are incorrect:

• Helium (option A) has atomic number 2, meaning it has 2 protons in its nucleus • Lithium (option C) has atomic number 3, with 3 protons in its nucleus • Boron (option D) has atomic number 5, containing 5 protons in its nucleus

The periodic table is arranged in order of increasing atomic numbers, starting with hydrogen at position 1. This systematic arrangement was developed by scientists to organize elements based on their atomic structure and properties. Understanding that atomic number equals the number of protons is fundamental to chemistry and helps us identify and distinguish between different elements.

Hydrogen is also the most abundant element in the universe, making up about 75% of all ordinary matter. It's found in water molecules (H₂O), organic compounds, and stars. Despite being the simplest element, hydrogen plays a crucial role in many chemical reactions and biological processes.