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Periodic Trends 6.3 Slide 1 of 31 3.2 Periodic Trends > Units and Quantities Warm Up What information can you find on the periodic table? Slide 2 of 31 © Copyright Pearson Prentice Hall 6.2 Periodic Trends > Squares in the Periodic Table Slide 3 of 31 © Copyright Pearson Prentice Hall 6.2 Periodic Trends > Squares in the Periodic Table Slide 4 of 31 © Copyright Pearson Prentice Hall 6.2 Periodic Trends > Electron Configurations in Groups The Representative Elements Elements in groups 1A through 7A: representative elements – The group number equals the number of electrons in the highest occupied energy level. Slide 5 of 31 © Copyright Pearson Prentice Hall 6.2 Periodic Trends > Transition Elements Blocks of Elements Slide 6 of 31 © Copyright Pearson Prentice Hall 6.3 Periodic Trends > Trends in Atomic Size Trends in Atomic Size What are the trends among the elements for atomic size? Slide 7 of 31 © Copyright Pearson Prentice Hall 6.3 Periodic Trends > Trends in Atomic Size Trends in Atomic Size What are the trends among the elements for atomic size? Slide 8 of 31 © Copyright Pearson Prentice Hall 6.3 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 increases from right to left across a period. Slide 9 of 31 © Copyright Pearson Prentice Hall 6.3 Periodic Trends > Trends in Atomic Size Slide 10 of 31 © Copyright Pearson Prentice Hall 6.3 Periodic Trends > Trends in Atomic Size Slide 11 of 31 © Copyright Pearson Prentice Hall 6.3 Periodic Trends > Ions Ions How do ions form? Slide 12 of 31 © Copyright Pearson Prentice Hall 6.3 Periodic Trends > Ions Positive and negative ions form when electrons are transferred between atoms. Slide 13 of 31 © Copyright Pearson Prentice Hall 6.3 Periodic Trends > Ions Positive and negative ions form when electrons are transferred between atoms. Slide 14 of 31 © Copyright Pearson Prentice Hall 6.3 Periodic Trends > 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. Slide 15 of 31 © Copyright Pearson Prentice Hall 6.3 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. Slide 16 of 31 © Copyright Pearson Prentice Hall 6.3 Periodic Trends > Trends in Ionization Energy Group and Periodic Trends in Ionization Energy First ionization energy tends to increase from bottom to top within a group and increase from left to right across a period. Slide 17 of 31 © Copyright Pearson Prentice Hall 6.3 Periodic Trends > Trends in first ionization energy Slide 18 of 31 © Copyright Pearson Prentice Hall Periodic Trends > Slide 19 of 31 © Copyright Pearson Prentice Hall 6.3 Periodic Trends > Trends in Ionic Size 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. Slide 20 of 31 © Copyright Pearson Prentice Hall 6.3 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. Slide 21 of 31 © Copyright Pearson Prentice Hall 6.3 Periodic Trends > Trends in Ionic Size Relative Sizes of Some Atoms and Ions Slide 22 of 31 © Copyright Pearson Prentice Hall 6.3 Periodic Trends > Trends in Electronegativity 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 increase from bottom to top within a group. For representative elements, the values tend to increase from left to right across a period. Slide 23 of 31 © Copyright Pearson Prentice Hall 6.3 Periodic Trends > Trends in Electronegativity Representative Elements in Groups 1A through 7A Slide 24 of 31 © Copyright Pearson Prentice Hall Periodic Trends > Shielding Effect The more energy levels between the nucleus and valence electrons shield the attractive force between the protons and electrons. This is why the atom expands in size. Slide 25 of 31 © Copyright Pearson Prentice Hall Periodic Trends > Reactivity Reactivity for metals increases as you move down and to the left (Fr). For non-metals reactivity increases as you move up and to the right (F). Slide 26 of 31 © Copyright Pearson Prentice Hall 6.3 Periodic Trends > Summary of Trends Summary of Trends What is the underlying cause of periodic trends? Slide 27 of 31 © Copyright Pearson Prentice Hall 6.3 Periodic Trends > Summary of Trends The trends that exist among these properties can be explained by variations in atomic structure. Slide 28 of 31 © Copyright Pearson Prentice Hall Section Assessment Assess students’ understanding of the concepts in Section 6.3 Continue to: -or- Launch: Section Quiz Slide 29 of 31 © Copyright Pearson Prentice Hall 6.3 Section Quiz 1. Which of the following sequences is correct for atomic size? a. Mg > Al > S b. Li > Na > K c. F > N > B d. F > Cl > Br Slide 30 of 31 © Copyright Pearson Prentice Hall 6.3 Section Quiz 2. Metals tend to a. gain electrons to form cations. b. gain electrons to form anions. c. lose electrons to form anions. d. lose electrons to form cations. Slide 31 of 31 © Copyright Pearson Prentice Hall 6.3 Section Quiz 3. Which of the following is the most electronegative? a. Cl b. Se c. Na d. I Slide 32 of 31 © Copyright Pearson Prentice Hall END OF SHOW