Know Nuclear

Science

Every piece of matter in the Universe, as far as we know, is made up of one or more elements from the Periodic Table. The smallest part of an element that can exist is an atom.

Nuclear Basics

Atoms are made up of  protons and neutrons, collectively called nucleons, surrounded by electrons.

Things you need to know:

• The atomic number of an element (Z) is the number of protons in a nucleus. This determines what the element is.
• The mass number of an element (A) is the number of nucleons in a nucleus. The number of neutrons in a nucleus is A-Z.
• Atoms of elements can contain different numbers of neutrons. Different forms are known as isotopes. The nucleus of an isotope is called a nuclide.
• Radioisotopes and radionuclides refer to radioactive forms of elements.
• A particular isotope of an element is defined by giving the name of the element and the mass number of the isotope. An example of this would be uranium-235.

The symbol is used for the nucleus of an element that has the chemical symbol X, a mass number A, and atomic number Z.

QUIZ YOURSELF

Question
The symbol  is used for a particular isotope. If A = 14 and Z = 6,

• How many protons does the isotope have in its nucleus?
• How many neutrons does the isotope have in its nucleus?
• What is the element X?

Answer

• The atomic number Z = 6 so the isotope has 6 protons in its nucleus.
• The number of neutrons in the nucleus of the isotope is A-Z = 14-6 = 8.
• The element that has an atomic number 6 is carbon.