The document discusses atomic structure and subatomic particles. It explains that atoms are made up of a nucleus containing protons and neutrons, surrounded by electrons. The nucleus is positively charged while electrons are negatively charged. Atoms are electrically neutral overall since the positive and negative charges balance out. Isotopes are atoms of the same element that differ in the number of neutrons. Valence electrons determine an element's chemical properties and atoms can gain or lose electrons to achieve a full outer shell, becoming ions in the process.

1. Atomic Structure…

3. The Electron Shell The Nucleus

4. Proton Nucleons Neutron The Nucleus

5. Charge + Proton 1

6. Charge 0 Neutron 1

7. The Electron Shell Electron

8. Charge _ Electron 1 1836

9. Sub-atomic Particles 1 1840 0

10. (+1) + 0 + (-1) = 0 Hence, the total charge of the atom is 0. In other words, the atom is electrically neutral

11. Nucleon No. Symbol Proton No.

12. 35 17 17 Tells us the no. of protons Proton No. Tells us the no. of electrons 17

13. Tells us the no. of protons +neutrons Nucleon No. No. of neutrons = Nucleon no. – Proton no. = 35 – 17 = 18 35 17

14. Let’s assess… Find the number of sub-atomic particles of the elements given.

17. Isotopes Chlorine has an atomic mass of 35.5 -Due to isotopes What are isotopes?

18. Isotopes Atoms of the same element with the same number of protons but different number of neutrons.

19. Isotopes Same chemical properties but slightly different physical properties. Why?

20. Isotopes Chemical reactions only involve electrons. Physical properties depend on the atomic mass. As isotopes only differ in atomic mass but not proton no., they will have slightly different physical properties.

21. Isotopes Radioisotopes Uses? Some isotopes emit high-energy radiation. Radiation can damage living cells but can be useful if used wisely.

22. How are electrons arranged?

24. Electrons are in orbit around the nucleus… Sort of like the planets around the Sun

25. Why must we know how electrons are arranged? Electron arrangement determines the chemical properties of the atom.

26. To ensure that the electron path is smooth sailing, the electrons are ‘assigned’ levels.

27. The first level only takes in 2 electrons. Subsequent levels can only take up to 8 electrons. Hence, once the level is filled up, the electrons will ‘create’ another level up to orbit in.

28. The way the electrons are arranged is called an electronic structure.

29. 3rd Shell 2nd Shell 1st Shell 2. 8. 8

30. Write an electronic structure of sodium atom Draw its atomic structure 2.8.1 11 p 12 n

31. Valence Electrons Valence = Outermost Valence shell = Outermost shell Valence electrons  Electrons on the outermost shell.

32. Valence Electrons Chemical property of an element depends on the valence electrons. Elements with the same number of valence electrons have similar chemical properties.

33. All atoms yearn for a full outermost shell. They will go around gaining or losing electrons to attain a full electron shell (2 or 8 electrons). Once they have attained the full shell, they would have a stable electronic structure.

34. Formation of Ions

35. Gaining of electrons: Outermost shell  6 electrons Need 2 electrons to be full. Electrons gained  2 electrons

36. The positive nucleus attracts the negative electrons

37. Overall charge Atom: Ion:

38. When electrons are gained, the overall charge is changed and atom becomes a negative ion. They are known as ANIONS 2- [ ] 16 O2- 8

39. Losing electrons: Outermost shell  2 electrons Electrons lost  2 electrons

40. Outermost shell disappears, exposing the next full shell.

41. Overall charge Atom: Ion:

42. When electrons are given away, the overall charge is changed and atom becomes a positive ion. They are known as CATIONS 2+ [ ] 24 Mg2+ 12

43. Try them yourselves! Write the electronic structure and draw the structure of the ions that will form from the following atoms. Na, Ca, Cl, O, N, F, K