Lesson 1

Hey guys!! Well today, I shall start my lesson officially. Alright, back to business, today I will be teaching you guys what is atomic structure.

Remember??

An atom is the smallest unit of an element, having the properties of the element.

Now, think about this. Are atoms small solid balls with nothing inside??

Ans : No. Why no?? Well, we are going to answer that question through this question.

Atoms -- made up of subatomic particles ( refer to the top image)

Particle Symbol Relatively mass Charge

Proton P 1 1+

Neutron N 1 0

Electron E 1/1836 1-

Wait a second, why is the term "relatively mass" used rather than the term just mass?

Before you can answer the question, let me give you some hints :

Mass of of proton =~1.67x10-27 kg.

Mass of neutron =~1.67x10-27 kg.

Mass of electron =~9.11x10-31 kg.

Well, mass of proton, neutron and electron are too small and inconvenient to work with and thus by using relative mass, we do not have to remember to the exact value of the various masses.

Proton number

-the number of protons in an atom is called the proton number. It is also be known as the atomic number.

To count the number of neutrons in an atom,

Firstly, you have to understand what is Nucleon number.

Nucleon number

-nucleon number is the number of protons and neutrons in the nucleus of an atom.

-it is also called as the Mass number.

Nucleon number (Mass ) number = neutrons + protons

The center of an atom is called the nucleus and it contains the number of protons + number of neutrons.

Electrons

As you all know that electron is a negative charge, now as you can refer from the top picture, electrons are arranged in shells (orbits) at different distances from the nucleus.

Note : Shells are also called energy level.

Each shell can hold a certain maximum number of electrons of.

(a) 1st shell : 2 electrons

(b)2nd shell : 8 electrons

(c) 3rd shell : 8 electrons (the 1st twenty elements)

Now, let me give you a little test.

Why is an atom electrically neutral?

Number of electrons = number of protons. Equal positive and negative charges.

However, why is the nucleus positively charged?

The nucleus contains protons and neutrons. As protons are positively charged while neutrons are electrically neutral, and thus the nucleus is positively charged.

Alright, that's all for today's lesson. Well, go and digest what I had taught here and be prepared for the next lesson!:D