Pre-class Activity How are library books classified? Why is such a classification system valuable?

History of the Periodic Table John Newlands (1864)  Recognized that when atoms are arranged by increasing mass, their properties repeated every eighth element which he named the “law of octaves”  Elements with similar properties were arranged in the same row  Did not work for all known elements Dimitri Mendeleev (1869)  Organized the first periodic table  Arranged elements by increasing atomic mass  Was able to predict the existence and properties of yet undiscovered elements

Modern Day Periodic Table Henry Moseley oArranged elements according to increasing atomic number instead of increasing atomic mass oDemonstrated a periodic repetition of chemical and physical properties called the periodic law

Organization of the Periodic Table Group Period

Questions What is the location, by group and period, of Boron? Group 13 Period 2 Which element is found in group 9, period 5? Rhodium

Main Group or Representative Group Elements s-block p-block 1A 2A 3A7A6A5A4A 8A

Transition Elements d-block f-block

Metals, Metalloids, and Nonmetals Metalloids

Metals Inner Transition Metals Transition Metals Alkali Metals Alkaline Earth Metals Other Metals

Properties of Metals Shiny Smooth Solid at room temp Malleable Ductible Conduct Electricity

Metalloids (Semimetals) B Boron C Carbon N Nitrogen O Oxygen F Fluorine Al Aluminium Si Silicon P Phosphorus S Sulfur Cl Chlorine Ga Gallium Ge Germanium As Arsenic Se Selenium Br Bromine In Indium Sn Tin Sb Antimony Te Tellurium I Iodine Tl Thallium Pb Lead Bi Bismuth Po Polonium At Astatine Metalloids contain physical and chemical properties of both metals and non-metals

Nonmetals Halogens Noble Gases Nonmetals are generally gases or brittle, dull-looking solids. They are poor conductors of electricity.

Valence Electrons For the Representative Elements, the group number corresponds to the number of valence electrons of atoms in that group.

classification of Elements s block p block d block f block

Questions How many valence electrons does Antimony (Sb) have? What is it’s Lewis Dot structure? 5Sb Which element is represented by the following electron configuration? [Xe] 6s 2 4f 14 3d 8 Platinum (Pt)

Periodic Trends in Atomic Radii From one group to the next, atomic radius decreases because the the electrostatic attraction between increasingly larger nuclei increases, pulling the electrons closer to the nucleus Decreases Increases From one row to the next, atomic radius increases because increasing numbers of neutrons shield the electrostatic force and valence electrons are located further and further away from the nucleus

Periodic Trends in Ionic Radii Decreases Increases From one row to the next, atomic radius increases because increasing numbers of neutrons shield the electrostatic force and valence electrons are located further and further away from the nucleus For positive ions, charge numbers increase as more electrons are lost from the atom. The electrostatic force is greater for smaller numbers of electrons which decreases the ionic radius. For negative ions, as the charge number increases, so does the number of electrons. Electrostatic forces decrease and the ionic radius increases in size.

Periodic Trends in Ionization Energy Increased nuclear charge that occurs from one group to the next accounts for electrons being held more tightly within the atom. The more tightly they are held, the greater the amount of energy that is required to remove and electron from an atom. The amount of energy required to remove an electron from an atom Increase Decrease From one row to the next, ionization energy increases because increasing numbers of neutrons shield the electrostatic force and valence electrons are located further and further away from the nucleus

Periodic Trends in Electronegativity Ability of an atom to attract electrons Increase Decrease