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Chapter 5

Chemistry. Chapter 5. Forerunners of the periodic table. a. End of 1700 ’ s – 30 elements known b. Early 1800 ’ s – discovering new elements by atomic spectroscopy. c. ______________________(German) – triads Elements could be classified into triads based on similar properties

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Chapter 5

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  1. Chemistry Chapter 5

  2. Forerunners of the periodic table a. End of 1700’s – 30 elements known b. Early 1800’s – discovering new elements by atomic spectroscopy. c. ______________________(German) – triads Elements could be classified into triads based on similar properties Li, Na, K, Ca, Sr, Ba, Cl, Br, I d. ____________________- arranged by  atomic mass. Properties of the 8th element were like those of the first, and so on. ______________________________.

  3. Cont: e. _____________________- Russian chemist i. Published the 1st periodic table arranged by increasing atomic mass- noticed the repetition of properties as well. (figure 5-4)‏ ii. Changed the order of three pairs of elements. iii. Also predicted the properties of yet unknown elements. He was correct on most predictions.

  4. Cont: iv. ________________- developed by H.G.J. Moseley- a student of Ernest Rutherford. 1. He discovered the relationship between an atom’s properties and its atomic number. 2. When elements are arranged in order of increasing atomic number, their physical and chemical properties show a periodic pattern.

  5. Section 2 I. Reading the periodic table . Shape- comes from the periodic law a. _______________ (families)- 18 1. Members are based on common properties shared by all members 2. Review names of groups - b. ____________________ (rows)‏ i. 7 ii. First one- ___ elements iii. 2nd and 3rd – _____ elements iv. 4th & 5th – ______ elements v. 6th & 7th – ______ elements

  6. Cont: II. Electron Configurations & the Per. Table a. The elements in each family are there because they have the same # of valence electrons. b. Groups 1 & 2 have 1 & 2 valence electrons and fill the s-sublevel. c. Groups 13-18 have 3 – 8 valence electrons and fills the p-sublevel. d. Groups 3-12 fill the d-sublevel.

  7. Section 3I. Periodic Trends a. __________________- the distance from the center of the atom’s nucleus to its outermost electron. Two trends: 1. Atoms get ________ as you go down a group 2. Atoms get _______________ from left to right.

  8. Cont: Trends b. ________________- i. Trends: 1. As an atom loses e- it gets smaller. 2. As an atom gains e- it gets bigger. c. ______________________- the energy needed to remove an e- from the atom. i. Measured when atoms are in the gas stage. Measured in units of kJ/mol

  9. Cont: Trends ii. Trends: 1. ___________ as you move down a group. 2. ____________ as you move from left to right. iii. Opposite the trends for atomic radius. Both depend on the valence electrons.

  10. Cont: Trends d. _____________________________- i. The energy required to remove 2nd and 3rd e- from atoms ii. Becomes increasingly more difficult the more that are removed. e. ________________- the energy change that occurs when an atom gains and e-. i. The measure of an atom’s attraction for an extra e-

  11. Cont: Trends • f.______________________- An atom’s ability to attract an electron. • i. _________________________ is the most electronegative atom.

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