Chapter 4 Periodic Table of Elements.ppt
- 1. Chapter 6: The Periodic Table
- 2. Organizing the Elements Demitri Mendeleeve (Russian – 1869) Published the 1st periodic table Based on atomic mass
- 3. The Periodic Law Modern Periodic Table Organized according to atomic number Periods = rows 1-7 equal to the principal energy level Groups = columns 1-18 elements have similar properties Law: Properties of elements repeat as you move from Left → Right across a period
- 4. Period → Group ↓
- 5. Metallic Character Approx. 2/3 of the elements are metals Metallic Properties Luster Conductivity Malleability Ductility Tend to lose electrons Nonmetallic Properties Dull luster Poor conductors Brittle Tend to gain electrons Metalloids (semimetals) Some properties characteristic of metals and other properties characteristic of nonmetals
- 7. Reference Table • Periodic Table Trends: 1. Across a period, metallic character → Why? More electrons in outer shells Less tendency to lose electrons 2. Down a group, metallic character → Why? Less electrons in outer shells Greater tendency to lose electrons decreases increases
- 8. Metallic Review Identify each element as a metal, nonmetal or metalloid a) Gold - b) Silicon - c) Sulfur - d) Barium - Metal Metalloid Nonmetal Metal
- 9. Which of these sets of elements have similar physical and chemical properties? a) oxygen, nitrogen, carbon, b) strontium, magnesium, calcium, beryllium c) nitrogen, neon, , fluorine Name 2 elements that have properties similar to those of the element sodium. Any other Group 1 element: Lithium, Potassium, Rubidium, Cesium, Francium boron nickel
- 10. Identify each property below as more characteristic of a metal or a nonmetal a) Brittle - b) Malleable - c) Poor conductor of electricity - d) Shiny - e) Tend to gain electrons - In which pair of elements are the chemical properties of the elements most similar? a) sodium and chlorine b) nitrogen and phosphorus c) boron and oxygen Nonmetal Metal Nonmetal Metal Nonmetal
- 11. Classifying the Elements Alkali Metals – Alkaline Earth Metals – Halogens – Noble Gases – Representative Elements – Transition Elements – Group 1 (1A) Group 2 (2A) Group 17 (7a) Group 18 (8A) Inert gases Groups 1A – 7A All Group B
- 13. Classifying Review Which of the following are symbols for representative elements Na, Mg, , Cl? Which of these metals is not a transition metal? a) Aluminum b) Silver c) Iron d) Zirconium Fe, Ni
- 14. Atomic Radius Atoms are roughly spherical Sphere size can be determined using the radius Problem: Solution: Atomic Radii – half the distance between the nuclei of identical atoms that are bonded together Edges of orbitals are fuzzy and difficult to measure…
- 15. Reference Table: • Table S Trends: 1. Across a period, the atomic radius → Why? Nuclei have larger positive charges Electrons are pulled in closer 2. Down a group, the atomic radius → Why? Greater number of energy shells Valence electrons are further away from the nucleus decreases increases
- 17. Atomic Radius Review Which element in each pair has a larger atomic radius? a) & lithium b) & bromine c) carbon & d) & neon Arrange these elements in order of decreasing atomic size: sulfur, chlorine, aluminum, and sodium. Sodium → Aluminum → Sulfur → Chlorine sodium calcium germanium fluorine
- 18. Ionization Energy What is an ion? An electrically charged atom Atoms may either gain or lose electrons Loss of electrons = (+) charge → Gain of electrons = (-) charge → Ionization energy = cation anion the amount of energy required to remove the most loosely bound electron A + energy A+ + e-
- 19. Reference Table • Table S Trends: 1. Across a period, the ionization energy → Why? Electrons are held closer to the nucleus Electrons are more difficult to remove 2. Down a group, the ionization energy → Why? Electrons are further away from the nucleus Electrons are easier to remove Relate Back: increases decreases What type of relationship exists between ionization energy and atomic radii? Inverse
- 21. Ionization Review Which element in each pair has a greater ionization energy? a) lithium, b) magnesium, c) cesium, Arrange the following groups in order of increasing ionization energy a) Be, Mg, Sr b) Bi, Cs, Ba c) Na, Al, S boron strontium aluminum Be → Mg → Sr Bi → Ba → Cs Na → Al → S
- 22. Ionic Size Cations from when atoms loose e- The cation is smaller Anions from when atoms gain e- The anion is larger
- 23. Reference Table • No true table Trends: 1. Across a period, ionic size → Why? When e- are lost, the attraction between the remaining e- increases e- are drawn closer to the nucleus 2. Down a group, ionic size → Why? Increased atomic radius e- are further away from the nucleus increases decreases
- 25. Ion Size Review Which particle has the larger radius in each atom/ion pair? a) Na, b) S, c) I, d) Al, The ions Na+ and Mg2+ each have 10e-. Which ion would you expect to have a smaller ionic radius? Mg2+ atomic radius is smaller & e- are pulled in closer Na+ S2- I- Al3+
- 26. Electronegativity A measure of the ability of an atom to attract a pair of electrons when bonded to another atom Ability to ‘pull’ electrons from another atom Electrons pulled closer: Electrons pulled away:
- 27. Reference Table • Table S Trends: 1. Across a period, the electronegativity → Why? Atoms are very close to a stable octet ‘Pull’ electrons from other atoms 2. Down a group, the electronegativity → Why? Top atoms have few electrons, and hold them tightly Bottom atoms have numerous electrons and little desire to acquire more increases decreases
- 29. Electronegativity Review Which element in each pair has a higher electronegativity value? a) Cl, b) C, c) Mg, d) As, Which element in each pair has a greater attraction for electrons? a) Ca or b) O or c) S F N Ne Ca O F or K
- 30. Decreases Increases Electronegativity Increases Decreases Ion Size Decreases Increases Ionization Energy Increases Decreases Atomic Radius Increases Decreases Metallic Character Variation down a Group Variation across a Period Periodic Property Summary