Question

The atomic number of an element is the total number of which particles in the nucleus?

Answer 1

An atom of element has there subatomic particles namely, proton, electron and neutron. Here, for a neutral atom, number of proton is equal to number of electron (this is not in the case of ions), this is equal to atomic number of an atom. In an atom, nucleus contains protons and neutrons which is responsible for mass of the atom and electrons move around nucleus in fixed orbits. Thus, atomic mass of an atom is equal to sum of number of protons and neutrons.

Option (b): Proton is the particle in nucleus of an atom, whose total number is equal to atomic number of that atom.

(4) Option (b): Atoms of same element have same atomic number because mass number can be different for different isotopes of atom. Since, atomic number is equal to number of protons, thus, number of protons are same for all atoms of the same element.

(5) Option (d): Isotopes are defined as atoms of same element with same atomic number but different mass number. Thus, correct option is (d) mass numbers.

Answer 2

The atomic number of an element is the total number of $\boxed{{\text{protons}}}$ in the nucleus.

All atoms of the same element have the same $\boxed{{\text{number of protons}}}$.

Isotopes of the same element have different $\boxed{{\text{mass numbers}}}$.

Further explanation:

The smallest particle that is the building block of matter is known as an atom. Most of the space in an atom is empty and its mass is concentrated inside a small region called the nucleus. An atom is also written as $_{\text{Z}}^{\text{A}}{\text{X}}$, where A is the atomic mass or mass number, Z is the atomic number and X is the letter symbol of the element.

Protons, electrons, and neutrons are the three subatomic particles that are present in the atom.

Proton is the subatomic particle with a positive charge. Neutron is the subatomic particle with no charge. Protons and neutrons are collectively called nucleons because these are located in the nucleus of the atom.

Electron is the negatively charged subatomic particle. In a neutral atom, the number of electrons is equal to the number of protons present in the nucleus of an atom. These revolve around the nucleus in definite orbits.

Atomic number is equal to the number of protons present in the nucleus of the atom. Atomic mass is the total number of nucleons (protons and neutrons) within the atomic nucleus. It is also known as the mass number.

Therefore the atomic number is equal to the number of protons present in the nucleus of an atom.

The atoms of the same element have the same atomic number. Since we know the atomic number is equal to the number of protons present in the nucleus of the atom.

Therefore the atoms of the same element will have the same number of protons in them.

Isotopes:

Atoms of the same element with the same atomic number but different mass numbers are called isotopes. These have the same number of protons but the number of neutrons is different. For example, $_{\text{6}}^{{\text{11}}}{\text{C}}$ and $_{\text{6}}^{{\text{12}}}{\text{C}}$ form isotopes of the same element carbon. These have the same atomic numbers (6) but different mass numbers (11 for $_{\text{6}}^{{\text{11}}}{\text{C}}$ and 12 for $_{\text{6}}^{{\text{12}}}{\text{C}}$).

Therefore the isotopes of the same element have different mass numbers.

Learn more:

1. Which two notations represent isotopes of the same element? brainly.com/question/2593342

2. The main purpose of conducting experiments: brainly.com/question/5096428

Answer details:

Grade: High School

Subject: Chemistry

Chapter: Structure of the atom

Keywords: Atomic number, nucleus, protons, isotopes, same element, mass numbers, number of protons, atoms.