Atomic Structure

An atom is the smallest particle of an element that retains the characteristics of that element.Each of the known 109 elements has atoms that are different from the atoms of all other elements.

According to the Bohr model, atoms have a planetary type of structure that consists of central

nucleus surrounded by orbiting electrons .The nucleus consists of positively charged particles called protons and uncharged particles called neutrons .The basic particles of negative charge are called electrons.

A look of helium atom is: