The document discusses the key concepts of elements, compounds, atoms, and molecules. It defines elements as pure substances that cannot be broken down further, and compounds as substances made of two or more elements bonded chemically. Atoms are the smallest particles of an element, with a nucleus containing protons and neutrons surrounded by electrons. Molecules are formed when two or more atoms of elements share electrons to achieve a stable electron configuration.

1. SUBSTANCE ELEMENT COMPOUND ATOM MOLECULE MOLECULE ION Pure metal Noble gases He, Ne, Ar Cu, Mg, Ag Two similar atoms of non metal element share their valence electron to achieve octet/duplet electron arrangement (group 15, 16 and 17) N 2, O 2 , Cl 2, Br 2, I 2, H 2 Two different non metal atoms of element share their valence electron to achieve octet/duplet electron arrangement ( between group 15, 16 and 17) CO 2 , H 2 O , SO 2 Metal atom (group 1, 2, 13 release electrons to form positive ion). Non metal atom (group 15,16,17 receive electrons) to achieve octet/ duplet electron arrangement NaCl , CuSO 4

2. ELEMENT A pure substance cannot be subdivided into any simpler substances by physical or chemical process COMPOUND A substance that contain two or more different types of elements that are chemically bonded together

3. DEVELOPMENT OF ATOMIC MODEL DALTON Idea of atom THOMSON Negatively charged electron Positively charged sphere RUTHERFORD Nucleus at the centre of atom contains positively charged proton Electrons move outside nucleus CHADWICK ATOMIC MODEL BOHR CHADWICK ATOMIC MODEL ELECTRON ARRANGEMENT FOR AN ATOM Na

4. Proton Electron Neutron 1 1/1840 1 +1 -1 0 Proton number : Total number of proton in the nucleus of an atom Nucleon number : Total number of proton and neutron in the nucleus of an atom In the nucleus In the shells Position Relative Charge Relative Mass Subatomic Particle

5. Standard Representation Of An Element X - Symbol of an element A – Nucleon number of atom X Z – Proton number of atom X A Z X

6. ATOM The smallest neutral particle of an element Normally pure metals, noble gases, a few non metal such as carbon and silicon Na

7. Sodium ELEMENT Sodium ELEMENT Sodium ELEMENT Sodium ELEMENT Sodium ATOM Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na

8. SODIUM ATOM Electron arrangement of sodium atom is 2.8.1 Na Na

9. SODIUM ELEMENT Sodium element consist with many sodium atoms Electron arrangement of sodium element is 2.8.1 Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na

10. Standard Representation For Sodium Element The Structure Of Sodium Atom         11p + 12n The Electron arrangement Of Sodium Atom 23 11 Na Na

11. 11 11 12 11 12 2.8.1 1 1 3 3 Period Number of shells Group Number of valence electrons Electron arrangement Nucleon number Proton number Number of neutron Number of electron Number of proton 23 11 Na

12. Electron Arrangements In Some Of Inert Gases Atoms All Inert Gases atoms have eight valence electrons (octet) except Helium which is stable. Helium atom has two valence electron (duplet) Why? Helium 2 (Duplet) Neon 2.8 (Octet) Argon 2.8.8 (Octet) He Ne Ar

13. EXAMPLE : PERIOD 3 ELEMENT 2.8.8 2.8.7 2.8.6 2.8.5 2.8.4 2.8.3 2.8.2 2.8.1 ELECTRON ARRANGEMENT 18 17 16 15 14 13 12 11 PROTON NUMBER Ar Cl S N Si Al Mg Na ELEMENT

14. GROUP PERIOD Inert Gases in The Periodic Table Of Element Why are these elements located in Group 18? I 2 13 14 15 16 17 18 1 2 3 4 5 6

15. Each atom from group 1-17 elements has 1,2,3,4,5,6 and 7 valence electrons respectively. They are not stable . Each atom does not achieve octet electron arrangement. How do these atoms achieve stable octet/duplet electron arrangement? Atoms form CHEMICAL BONDS to achieve a stable duplet or octet electron arrangement. Bonds are formed when two or more atoms of elements are bonded together.

16. There are TWO TYPES OF CHEMICAL BOND: 1. IONIC BOND ( Particles form are positive ion and negative ion ) 2. COVALENT BOND. ( Particle forms is neutral molecule )