The document summarizes atomic structure. It explains that atoms are made up of protons, neutrons, and electrons. Protons are positively charged and have a mass of about 1 atomic mass unit. Neutrons are neutral and also have a mass of about 1 atomic mass unit. Electrons are negatively charged and have a negligible mass. The nucleus of an atom contains protons and neutrons, and electrons orbit the nucleus in shells. For example, hydrogen has 1 proton, 1 electron, and no neutrons, while helium has 2 protons, 2 neutrons, and 2 electrons. The mass number of an atom is the total number of protons and neutrons, and the proton number indicates how many protons an atom contains. Electron shells

1. Atomic structure

2. Atomic Structure

3. The structure of the atom
ELECTRON –
negative, mass
nearly nothing
PROTON –
positive, same
mass as
neutron (“1”)
NEUTRON –
neutral, same
mass as proton
(“1”)
The Ancient Greeks used to believe that
everything was made up of very small particles.
I did some experiments in 1808 that proved
this and called these particles ATOMS:
Dalton

4. The Atom
Nucleus Electron
Shell or Orbit

5. The Atom Hydrogen
Proton Electron
Hydrogen has one proton, one electron and NO neutrons

6. The Atom Helium
ElectronProton
Neutron
Helium has two electrons, two protons and two neutrons

7. Mass and atomic number
Particle Relative Mass Relative Charge
Proton 1 1
Neutron 1 0
Electron 0 -1
MASS NUMBER = number of
protons + number of neutrons
SYMBOL
PROTON NUMBER = number of
protons (obviously)

8. How many protons, neutrons and electrons?

9. How shells fill
• The first electron shell can only hold a
maximum of two electrons.
• The second electron shell can hold a
maximum of eight electrons.
• The third electron shell can also hold a
maximum of eight electrons.
• The fourth electron shell can also hold eight
electrons.

10. THANK YOU
• By Ishan Kelkar