Periodic Table

1. Periodic Table I. Mendeleev A. Russian Chemist - In 1869 - organized elements according to their properties B. Arranged elements according to their increasing atomic mass - this but some of them out of order 1. found a reoccurring pattern with in the elements a. Referred to pattern as periodic.

2. C. left gaps for undiscovered elements - gave chemists an insight to look for these elements 1. elements with atomic masses of 44, 68,72, and 100 2. these elements where a. Scandium (1879), Gallium(1875),Germanium, and Technetium respectively II Moseley ( 1887-1915) A. did work with x-ray determination of atomic numbers B. Led to arranging the elements by increasing atomic number

3. III. Periodic Law A. The physical and chemical properties of the elements are periodic functions of their atomic number IV Modern Periodic Table (long form)

5. A. Arranged by increasing atomic number B. Horizontal Rows known as series or periods 1. Increase in atomic number by 1 2. Lanthanide series and the actinide series - last two rows at the bottom of the periodic table

7. C. Vertical rows known as groups or Families 1. Group 1 - Alkali metals - React with violently with water. Not found alone in nature, soft silvery metals. Also known as the Sodium Family

10. 2. Group 2 - Alkaline earth metals - less reactive then the alkali metals - also known as the Calcium family

12. 3. Group 17 - Halogen family - bleaching tendencies, very reactive

15. 4. Group 18 - inert or noble gas family - mostly non-reactive

19. D. Blocks 1 s block - first two columns 2. p block - last 6 columns

20. p block s block

24. Atomic Radii Ionization Energy Electron Affinity Ionic Radii Electronegativity

25. V Trends on the periodic table A. Atomic Radius - distance between the center of the nucleus to the outer most electrons 1. no real way to measure just the radius of atoms a. best method is to measure the distance between two adjacent atoms

27. i. covalent radius - half the distance between the nuclei of two identical atoms ii. ionic radius - half the distance between two nucleus of ions held together by an ionic bond iii. metallic radius - half the distance between nuclei of two atoms in contact in a crystal 2. Going down the Families - Atomic radius increases a. why - the increasing number of energy levels make the atom larger - like adding floors onto a hotel i. shielding affect - that is where the inner electrons shields the outer electrons from the nucleus

28. 3. Going across the periods from left to right - atomic radius decreases a. why - the more protons in the nucleus draws the electrons in tighter

30. Remember - Electrons like to be held tight to the nucleus Nucleus electron

31. B. Ionization energy - energy required to remove the outer most electrons 1. going down a family - ionization energy decreases ( it easier to remove and electron from the elements at the bottom) a. why - electrons are farther away from the nucleus and are held less strongly thus allowing them to be removed with less energy 2. Going across a period - from left to right - ionization energy increases a. why - electrons are held tight to the nucleus which makes it more difficult to remove them

32. When the Mg atom loses an electron - it will have more protons than electrons and therefore acquire a +1 charge. Known as an ion

36. C. Electron affinity- “love for electrons” 1. Going across the periodic table from left to right - electron affinity increases a. why - electrons like to be held tight to the nucleus. We already know that atoms on the right side of the periodic table have a small atomic radius and hold on to their electrons tight 2. Going down the periodic table - electron affinity decreases a. why - electrons are held less tightly due to the size of the atom

37. The N atom gains an electron, it will have more electrons than protons and there-fore acquire a negative charge

39. Electronegativity,   is a measure of the ability of an atom in a molecule to attract electrons to itself. Concept proposed by Linus Pauling 1901-1994

40. D. electronegativity - ability to attract a shared pair of electrons 1. going down a family - electronegative decreases a. why - the size of the atom limits the ability of an atom to hold on to its own electrons let alone to attract another one 2. going across the periodic table from left to right - the electronegativity increases a. why - since the atom is smaller the positive charge of the nucleus can break outside the atom and attract another electron

41. E. Reactivity 1. There is a certain stability for an atom when there is eight electrons in the outer shell (octet) 2. since atoms on the left side of the period table want to lose electrons - the ones on the bottom of the chart are more reactive because they give up their electrons the easiest 3. since the atoms on the right side of the periodic table want to gain electrons in order to obtain an octet - the ones on the top are the most reactive

42. Reactivity I n c r e a s I n g I n c r e a s I n g

43. F. ionic radius - the distance from the center of the nucleus to the outer most energy level 1. ions - an atom or group of atoms with unequal number of protons and electrons a. cations - positive ions - smaller than atom due to greater number of protons than electron b. anions - negative ions - larger than there atom due to a greater number of electrons than protons 2. the elements on the left side of the periodic table will form cations by losing an electron in order to obtain an octet and therefore become smaller

44. 3. the elements on the right side of the table will form anions by gaining electrons and therefore become larger 4. removing a second electron becomes much more difficult due to the increased attraction between the nucleus and the electrons

47. G. Metals on the left side of the periodic table H. Nonmetals are on the right J. transition metals are in the middle

48. For review On page 156 2,8,9,10,17,18,24,26, 29,45,46