atomic structure

 Atom have spherical particles like minute lead shots(pellet)

 minute lead shot meaning:  is a collective term for small balls or pellets, often made of lead. ... Lead shot was originally made by pouring molten lead through screens into water, forming what was known as "swan shot", and, later, more economically mass-produced at higher quality using a shot tower.

4 ideas of dalton's atomic theory

1) All matter is made of atoms. 

2)Atoms are indivisible and indestructible.

 3) Compounds are formed by a combination of two or more different kinds of atoms. 

4) A chemical reaction is a rearrangement of atoms

POINT OF Bohr

The tritium nucleus, or triton, is unstable simply because it is more massive than its decay products which are a helium-3 nucleus, an electron, and an electron anti-neutrino. Its decay products are more stable. This is called beta decay.

Radioisotopes are atoms that contain an unstable combination of neutrons and protons, or excess energy in their nucleus.

Difference Between Atom And Element

1: FACT

 More: https://examples.yourdictionary.com/difference-between-atoms-and-elements-with-examples.html

2: FACT

https://byjus.com/chemistry/difference-between-elements-and-atoms/

Electronic Configuration is arrengement of electrons in shell

 Hydrogen and Oxygen atoms are so reactive that they combine with almost all elements.

How to calculate valency?

Why do higher energy levels have more energy OR Distant electron have more energy than electron in shell that is close to nucleus?

Tritium (abbreviated as 3H) is a hydrogen atom that has two neutrons in the nucleus and one proton. 

Archivement of Mendeleevs

• Left gaps for predicted element
• Position of noble gas

Limitation of Mendeleevs

• No Fixed position for H
• Position of Isotopes - bcoz descovered later
• not predict how many element would be discovered

Periodicity

The tendency of chemical elements to have similar properties when arranged according to their atomic number.