Atom and Elements | First 20 Elements of Periodic Table

ATOM AND ELEMENTS | FIRST 20 ELEMENTS OF PERIODIC TABLE

MEANING OF ATOM

An atom is the smallest particle of matter that cannot be seen with the naked eye. Atoms make up everything around us – air, water, plants, animals, and objects.

Atoms combine to form molecules.

Example – Water is made of atoms of hydrogen and oxygen.

Elements of an Atom

An atom is made up of three main subatomic particles called elements of an atom:

a) Protons

• Positively charged particles (+)

• Found in the nucleus (center) of the atom

• Determine the identity of an element

b) Neutrons

• Neutral particles (no charge)

• Also found in the nucleus

• Help stabilize the atom

c) Electrons

• Negatively charged particles (-)

• Move around the nucleus in electron shells

• Involved in chemical reactions and bonding

Diagram of an Atom (Simple)

Electron (-)

 o

↓

      [ Nucleus ]

      /                \

         Proton (+)       Neutron (0)

Summary – An atom is the smallest particle of matter. It is made of protons (+), neutrons (0), and electrons (-).

MEANING OF ELEMENTS

An element is a pure substance made of only one type of atom. Elements cannot be broken down into simpler substances by ordinary chemical methods.

Each element has a unique symbol in chemistry. The table below shown,

First 20 Elements of the Periodic Table