What is atomic structure ?

• All substances are made of tiny particles of matter called atoms .

• each atom is made of subatomic particles called protons, neutrons and electrons.

• Neutrons and protons are located in the nucleus.

• The electrons move very fast around the nucleus in orbital paths called shells

• The structure on an atom

Protons , Neutrons and Electrons

• The size of the atoms is so tiny that we cant really compare their masses in conventional units such as kilograms and grams . so a unit called relative atomic mass is used

• One relative atomic mass unit is equal to 1/12th of the mass of a carbon -12 atom

protons - relative atomic mass -1, charge - 1-

Defining atomic number

• The atomic number or proton number is the number of protons in the nucleus of an atom

• The symbol of atomic number is z

  
  
  
  

  Defining mass number

• the nucleon number or mass number is the total number of protons and neutrons of an atom

• the symbol for nucleon number is A

• the nucleon number minus the proton number gives you the number of neutron of an atom

• the atomic number and mass number of an element can be shown using atomic notation

How to calculate number of protons , electrons and neutrons

• mass number= number of protons +number of neutrons

• number of protons =mass number - number of neutrons

• electrons = an atom is neutral and therefore has the same number of protons and electrons

Neutrons

• the mass and atomic number can be used to find the number of neutrons and ions and atoms

• number of neutrons = mass number - number of protons .