Chapter 5 - Periodic Trends PDF

The Periodic Table and Trends Lecture Chapter 5 – SHCHEM1 Natural Science Cluster Prepared by: Mc. Benrick Porras OBJECTIVES Explain the periodic recurrence of similar properties among elements in the periodic table in terms of electronic structure. Relate the number of valence e...

The Periodic Table and Trends Lecture Chapter 5 – SHCHEM1 Natural Science Cluster Prepared by: Mc. Benrick Porras OBJECTIVES Explain the periodic recurrence of similar properties among elements in the periodic table in terms of electronic structure. Relate the number of valence electrons of elements to their group number in the periodic table. Describe and explain the trends in atomic properties in the periodic table. History of the Periodic Table History of the Periodic Table History of the Periodic Table PARTS OF THE PERIODIC TABLE Group and Period Main Group Elements – elements have unfilled or filled s and p orbitals in the highest principal quantum number. Transition Elements – d subshells are being filled up. Lanthanides and Actinides - are chemical elements in the f block transition elements because they have incompletely filled f subshells. Group and Period Group Period Group – Vertical columns are called groups; they share similar chemical properties because of same number of valence electrons. Periods – Horizontal columns are called periods; Elements in the same period have the same number o electron shells. Group and Period Group – Vertical columns are called groups; they share similar chemical properties because of same number of valence electrons. Periods – Horizontal columns are called periods; Elements in the same period have the same number o electron shells. Group and Period - Across a period, elements increase in atomic number. - Down a group, elements increase in number of electron shells Group – Vertical columns are called groups; they share similar chemical properties because of same number of valence electrons. Periods – Horizontal columns are called periods; Elements in the same period have the same number o electron shells. Group and Period Group – Vertical coloumns are called groups; they share similar chemical properties because of same number of valence electrons. Periods – Horizontal coloumns are called periods; Elements in the same period have the same number o electron shells. Group and Period Group – Vertical coloumns are called groups; they share similar chemical properties because of same number of valence electrons. Periods – Horizontal coloumns are called periods; Elements in the same period have the same number o electron shells. Group and Period Group and Period Metals, Non-metals, and Metalloids Metals, Non-metals, and Metalloids Blocks Blocks Blocks Blocks Valence Electrons of various blocks Ionic Charge trend of various groups Ionic Charge trend of various groups  PERIODIC TRENDS The periodic table was constructed on the basis of trends (periodicity) in chemical properties. The chemical reactivity of the elements is determined by their valence electrons, the outermost electrons. The valence electrons are the electrons that participate in chemical bonding. PERIODIC TRENDS – Atomic Radii It is defined as one half the distance between two nuclei in two adjacent metal atoms or diatomic molecules. The size of an atom is determined by the size of its outermost occupied orbital. Atomic radii of the main-group elements (in picometers). PERIODIC TRENDS – Atomic Radii On the periodic table, atomic radius generally decreases as you move from left to right across a period (due to increasing nuclear charge) and increases as you move down a group (due to the increasing number of electron shells) Atomic radii of the main-group elements (in picometers). PERIODIC TRENDS – Atomic Radii PERIODIC TRENDS – Atomic Radii PERIODIC TRENDS – Atomic Radii Cation is always smaller than atom from which it is formed. Anion is always larger than atomfrom which it is formed. Size: Cation < Neutral Atom < Anion PERIODIC TRENDS – Atomic Radii Which of the following elements has the greatest atomic radius? N C B O F PERIODIC TRENDS – Atomic Radii Which of the following elements has the smallest atomic radius? N Bi As P PERIODIC TRENDS – Atomic Radii PERIODIC TRENDS – Atomic Radii PERIODIC TRENDS – Electronegativity tendency of an atom to attract electrons to form a bond. Can be called “electron affinity” PERIODIC TRENDS – Electronegativity tendency of an atom to attract electrons to form a bond. Can be called “electron affinity” PERIODIC TRENDS – Electronegativity Which of the following elements is the most electronegative? Titanium Barium Gallium Helium Phosphorus PERIODIC TRENDS – Electronegativity Which of the following has the highest electronegativity value? Cesium Carbon Zinc Mercury Fluorine PERIODIC TRENDS – Electronegativity Arrange the elements from the highest electronegativity to the lowest. Na Cl C Mg S PERIODIC TRENDS – Ionization Energy Ionization Energy - energy needed to remove outermost electrons PERIODIC TRENDS – Ionization Energy PERIODIC TRENDS – Ionization Energy PERIODIC TRENDS – Ionization Energy PERIODIC TRENDS – Metallic Character Metallic Character - set of chemical properties that are associated with the elements classified as metals PERIODIC TRENDS – Metallic Character Which of the following elements has the most metallic character? P As Sb Bi