1. Slide 1 of 31 © Copyright Pearson Prentice Hall Periodic Trends > Trends in Atomic Size The atomic radius is one half of the distance between the nuclei of two atoms of the same element when the atoms are joined. 6.3

2. Slide 2 of 31 © Copyright Pearson Prentice Hall Periodic Trends > Trends in Atomic Size Group and Periodic Trends in Atomic Size In general, atomic size increases from top to bottom within a group and decreases from left to right across a period. 6.3

3. Slide 3 of 31 © Copyright Pearson Prentice Hall Periodic Trends > Trends in Atomic Size 6.3

4. Slide 4 of 31 © Copyright Pearson Prentice Hall Periodic Trends > Trends in Atomic Size 6.3

5. © Copyright Pearson Prentice Hall Periodic Trends > Slide 5 of 31 Ions How do ions form? 6.3

6. © Copyright Pearson Prentice Hall Slide 6 of 31 Periodic Trends > Ions Positive and negative ions form when electrons are transferred between atoms. 6.3

7. © Copyright Pearson Prentice Hall Slide 7 of 31 Periodic Trends > Ions Positive and negative ions form when electrons are transferred between atoms. 6.3

8. Slide 8 of 31 © Copyright Pearson Prentice Hall Periodic Trends > Ions Some compounds are composed of particles called ions. An ion is an atom or group of atoms that has a positive or negative charge. A cation is an ion with a positive charge. An anion is an ion with a negative charge. 6.3

9. © Copyright Pearson Prentice Hall Periodic Trends > Slide 9 of 31 Trends in Ionization Energy What are the trends among the elements for first ionization energy, ionic size, and electronegativity? 6.3

10. Slide 10 of 31 © Copyright Pearson Prentice Hall Periodic Trends > Trends in Ionization Energy The energy required to remove an electron from an atom is called ionization energy. The energy required to remove the first electron from an atom is called the first ionization energy. The energy required to remove an electron from an ion with a 1+ charge is called the second ionization energy. 6.3

11. Slide 11 of 31 © Copyright Pearson Prentice Hall Periodic Trends > Trends in Ionization Energy Group and Periodic Trends in Ionization Energy First ionization energy tends to decrease from top to bottom within a group and increase from left to right across a period. 6.3

12. Slide 12 of 31 © Copyright Pearson Prentice Hall Periodic Trends > Trends in Ionization Energy 6.3

13. Slide 13 of 31 © Copyright Pearson Prentice Hall Periodic Trends > Trends in Ionization Energy 6.3

14. © Copyright Pearson Prentice Hall Slide 14 of 31 Periodic Trends > Trends in Ionization Energy 6.3

15. Slide 15 of 31 © Copyright Pearson Prentice Hall Periodic Trends > Trends in Ionic Size During reactions between metals and nonmetals, metal atoms tend to lose electrons, and nonmetal atoms tend to gain electrons. The transfer has a predictable effect on the size of the ions that form. 6.3

16. Slide 16 of 31 © Copyright Pearson Prentice Hall Periodic Trends > Trends in Ionic Size Cations are always smaller than the atoms from which they form. Anions are always larger than the atoms from which they form. 6.3

17. Slide 17 of 31 © Copyright Pearson Prentice Hall Periodic Trends > Trends in Ionic Size Relative Sizes of Some Atoms and Ions 6.3

18. © Copyright Pearson Prentice Hall Slide 18 of 31 Periodic Trends > Trends in Ionic Size 6.3 Size generally increases

19. Slide 19 of 31 © Copyright Pearson Prentice Hall Periodic Trends > Trends in Electronegativity Electronegativity is the ability of an atom of an element to attract electrons when the atom is in a compound. In general, electronegativity values decrease from top to bottom within a group. For representative elements, the values tend to increase from left to right across a period. 6.3

20. Slide 20 of 31 © Copyright Pearson Prentice Hall Periodic Trends > Trends in Electronegativity Representative Elements in Groups 1A through 7A 6.3

21. © Copyright Pearson Prentice Hall Periodic Trends > Slide 21 of 31 Summary of Trends What is the underlying cause of periodic trends? 6.3

22. Slide 22 of 31 © Copyright Pearson Prentice Hall Periodic Trends > Summary of Trends The trends that exist among these properties can be explained by variations in atomic structure. 6.3

23. © Copyright Pearson Prentice Hall Slide 23 of 31 Periodic Trends > Summary of Trends 6.3 Atomic Size Increases Decreases Size of cationsShieldingNuclear ChargeElectronegativityIonization energySize of anions Ionic size Constant