8-A-Trends-of-the-periodic-table-atomic-sizes-Copy.pptx

Grade 8 Trends of the periodic table

1. Trends of the periodic table – Atomic sizes Alvin Leo T. Suasin

2. objectives Describe the trend of atomic sizes down the group and across the period. Arrange elements in the order of increasing atomic sizes. 2

3. Review How are elements arranged in the periodic table? Answer: The elements are arranged in the order of increasing atomic numbers. If the atomic number is 11, how many protons are there? Answer: 11 If the atomic number is 11 and mass number is 23, how many neutrons are there? Answer : 12 3

4. Complete the term _______________ng effect Answer: shield ing effect 4

5. Complete the terms and Answer: atomic radius 5

6. Trends of atomic sizes in a group Describe the number of energy levels in a group (from top to bottom). answer: The number of energy levels is increasing . 2. What is the effect of the additional energy levels in the sizes of elements? answer: As the number energy levels increase, the sizes of atoms also increase. 6

7. Trends of atomic sizes in a group What is the trend of atomic sizes in a group(from top to bottom)? Answer: increasing 7

8. Trends of atomic sizes in a group As the number of energy levels increases down a group the shielding effect and atomic sizes increase. 8

9. Shielding/screening effect 9

10. Trend of atomic sizes in a period Note: +3 means 3 protons Describe the number of protons in a period. Answer: The number of protons in a period is increasing. Describe the number of energy levels in a period. Answer: The number of energy levels are the same. 10

11. Trend of atomic sizes in a period Compare the ability of the nucleus in pulling the outermost electron. . Within a period, protons are added to the nucleus as electrons are being added to the same number of energy levels. These electrons are gradually pulled closer to the nucleus because of its increased positive charge. Since the force of attraction between nuclei and electrons increases, the size of the atoms decreases.  11

12. What can you say about the Trend of atomic sizes in a period? 12 The trend of atomic size in period is decreasing.

13. Describe the Trend of atomic sizes in a group and period. 13

14. exercises Which of the following has the greatest atomic size? Na, Fr, Li, Cs P, Mg, S, Na Answers: Fr Na 14

15. exercises II . Arrange the following in the order of increasing atomic sizes. O, Be, F, B Br, I, F, At Ge, B, Ca, He Answers: F, O, B, Be F, Br, I, At He, B, Ge, Ca 15

16. ( ESP ) The importance of order during flag ceremony/retreat Find your height Form a straight line Minimize your noise Emphasizes: Discipline Nationality Obedience to the school policy Respect 16

17. conclusion 17

18. conclusion 18

19. Group work ! Find your atomic sizes group1 group2 group3 group4 group5 19

20. Group work ! Find your atomic sizes group1 group2 group3 group4 group5 Ar , Si, S, Na, Al, Mg, Ge ( group1 ) At, I, Cl, O, Br, F, B ( group 2 ) Ca, Sr, Br, Ga, Kr, Zr, Ge ( group 3 ) Ge, C, Au, O, Pb, Si ( group 4 ) Al, Br, H, O, N, He ( group 5 ) 20

21. Group work ! Find your atomic sizes Answers Ar , S, Si, Al, Mg, Na, Ge F, O, B, Cl, Br, I , At, Ge Kr, Br, Ge, Ga, Ca, Zr, Sr O, C, Si, Ge, Pb, Au H, He, O, N, Al, Br 21

22. Thank you Grade 8 – Probers (Einstein, Mendel, Newton, Pasteur) 22