This document defines key concepts in chemistry including matter, atoms, molecules, subatomic particles, atomic number, mass number, moles, and the periodic table. It explains that atoms are made up of protons, neutrons, and electrons. The atomic number is the number of protons, and the mass number includes both protons and neutrons. It also defines what a mole is and how it relates to atomic mass. The periodic table is arranged based on atomic number and electronic configuration.

4. What are these ? These are the substances having mass and occupies space So, They are called matter .

5. An atom is a tiny particle made up of proton Neutron & electrons. Molecule Eg- Hydrogen atom, Nitrogen atom A molecule is group of similar or dissimilar atoms . Example _ H 2 O, C 6 H 12 O 6 Atom

10. NEUTRON Neutrons Protons Electrons

12. ELECTRON

16. Atomic mass and number can be represented as follows:

17. NUCLEONS

19. AVOGADRO

20. Problem on mole Calculate the mole value of Methane ( CH 4) ( C = 12, H = 1 ) Atomic mass of Carbon ---  01 X 12 = 12 Atomic mass of Hydrogen -  04 X 01 = 04 Atomic mass of Methane -  16  One mole of Methane -  16 X 01 gm = 16 gm

22. MENDLEEVE

29. CONTINUED ( E . C ) Sub-Orbit Electron gain capacity s 2 p 6 d 10 f 14

30. ELECTRONIC CONFIGURATION

31. FILLING OF ELECTRONS 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 7s 7p 7d