2. Atoms T. M. Yeung 2000

3. w What is the particle that made up an element?

4. Atoms w All elements are made up of small particles called atoms. w Different elements have their unique kind of atoms. w The atoms of iron are different from that of carbon.

5. Gold and its Atoms

6. Different Elements are made up of different atoms a silver wire silver atoms enlarged many, many times a copper wire copper atoms enlarged many, many times

7. Basic Structure of Atom

8. Solar System

9. Basic Structure of Atom

10. Atomic Number & Mass Number w An Atom is electrically neutral, that means w No. of proton(s) in an atom = No. of electron(s) in the same atom w Atomic Number (Z) of an atom = No. of proton(s) of the atom w Mass Number (A) of an atom = No. of proton(s) + No. of neutron(s)

11. Example w What is the atomic number and the mass number of the atom shown below? neutron electron proton nucleus Atomic number is 2 and mass number is 4

12. Class-work

13. Notation of Atom w X = symbol of element w Z = atomic number w A = mass number

14. Notation of Atom w Atomic no. =? w 92 w Mass no. =? w 235 w No. of the neutron =? w 143 w Name =? w Uranium

15. Atomic Bombing at Nagasaki

16. Class-work

17. Isotopes of Hydrogen

20. Chemistry Dictation w First 20 elements w 10 minutes:

21. Relative Atomic Mass w The mass of a hydrogen atom is only 1.66 x 10 -24 g! w The mass of a carbon atom is only 2 x 10 -23 g! (0.00 000 000 000 000 000 000 002g!) w Carbon-12 atom is being taken as the reference standard. w The relative atomic mass of carbon-12 atom is defined as 12 units.

22. w Most elements have more than one isotope, and different isotopes have different masses. w The relative atomic mass of an element is the average mass of its isotopes compare with an atom carbon-12. Relative Atomic Mass

23. w IsotopePercentage abundance 35 Cl75% 37 Cl25% w Relative atomic mass of chlorine, Cl: 75/100 x 35 + 25/100 x 37 = 35.5 (a.m.u.) # w Relative atomic mass of lead, Pb: 2/100 x 204 + 24/100 x 206 + 22/100 x 207 + 52/100 x 208 = 207.2 (a.m.u.) #

24. Electron Arrangement of Atoms nucleus

25. Electron Arrangement of Atoms w Oxygen atom w Atomic no. = 8 w No. of protons = No. of electrons = 8 w Electron arrangement = 2, 6 O Electron

26. Electron Arrangement of Atoms w Oxygen atom w Atomic no. = 8 w No. of protons = No. of electrons = 8 w Electron arrangement = 2, 6 Electron O

27. Electron Arrangement of Atoms w Oxygen atom w Atomic no. = 8 w No. of protons = No. of electrons = 8 w Electron arrangement = 2, 6 O Electron

28. Electron Arrangement of Atoms w Oxygen atom w Atomic no. = 8 w No. of protons = No. of electrons = 8 w Electron arrangement = 2, 6 O Electron

29. Electron Diagram of Oxygen Atom O electron w Two electrons in the first shell. w Six electrons in the second shell. w Electron arrangement = 2, 6

30. Electron Diagram of Aluminium Atom w Atomic no. = 13 w Electron arrangement =2, 8, 3 w Two electrons in the first shell. w Eight electrons in the second shell. w Three electrons in the third shell Al

31. Electron Diagram of Magnesium Atom w Atomic no. = 12 w Electron arrangement = 2, 8, 2 Mg

32. Electron Diagram of Fluorine Atom w Atomic no. = 9 w Electron arrangement = 2, 7 F

33. Electron Diagram of Boron Atom w Atomic no. = 5 w Electron arrangement = 2, 3 B

35. Simple Ions w A simple ion is formed when an atom either loses or gains one or more electrons. w It is either positively or negatively charged. w Positive ions are called cations.

36. Simple Ion

37. Simple Ion: Cation w Lithium atom, Li: w Atomic no. = 3 w Electron arrangement = 2, 1 w Remove one electron from the outermost shell of lithium atom... Li

38. Simple Ion: Cation w Lithium ion, Li + : w Atomic no. = 3 w Electron arrangement = 2 w Three protons w Two electrons w Positively charged particle! Li +

39. Simple Ion: Anion w Fluorine atom, F: w Atomic no. = 9 w Electron arrangement = 2, 7 w Add one electron to the outermost shell of fluorine atom... F

40. Simple Ion: Anion w Fluoride ion, F - : w Atomic no. = 9 w Electron arrangement = 2, 8 w Nine protons w Ten electrons w Negatively charged particle F -

41. References w Atomic Bomb http://www.geocities.com/Athens/Agora/4526/i ndex1.html w Encarta 98 w General Chemistry http://www- wilson.ucsd.edu/education/gchem/index.html w General Chemistry I -- A Virtual Textbook http://wine1.sb.fsu.edu/chm1045/chm1045.htm