Atomic Number, Isotopes, and Isobars: Introduction

Questions and Answers

Number of protons + Number of neutrons

Isotopes

Due to the same number of protons

Different atomic numbers, same mass numbers Signup and view all the answers

Number of electrons Signup and view all the answers

The number of protons in the nucleus of an atom Signup and view all the answers

By establishing the atomic number concept based on protons Signup and view all the answers

Because atoms are electrically neutral Signup and view all the answers

Hydrogen Signup and view all the answers

Protons equal electrons Signup and view all the answers

Study Notes

Atomic number (Z) is the number of protons in the nucleus of an atom, which is equal to the number of electrons in a neutral atom.
Atomic number is represented by Z and determines the chemical properties of an element.
Hydrogen has an atomic number of 1, as it has only one proton in its atom.
Mass number (A) is the total number of protons and neutrons present in the nucleus of an atom.
Mass number is represented by A and is the sum of protons and neutrons in an atom.

Isotopes are elements with the same atomic number but a different mass number.
Isotopes occur due to the presence of a different number of neutrons in elements with the same atomic number.
Many but not all elements have isotopes.
Examples of isotopes of hydrogen are protium (1 proton, 0 neutrons), deuterium (1 proton, 1 neutron), and tritium (1 proton, 2 neutrons).
Chemical properties of isotopes are the same due to the same number of protons and electrons.

Isobars are atoms with the same mass number but a different atomic number.
Examples of isobars include Argon (atomic number 18, mass number 40), Potassium (atomic number 19, mass number 40), and Calcium (atomic number 20, mass number 40).
Carbon-14 (mass number 14) is an isobar of Nitrogen (atomic number 7, mass number 14).