The Periodic Table The Periodic Table is used to organize the 114 elements in a meaningful way. As a consequence of this organization, there are periodic properties associated with the periodic table.

Natural States of the Elements Most elements are very reactive. Elements are not generally found in uncombined form. Exceptions are: Noble metals – gold, platinum and silver Noble gases – Group 18

The Periodic Table Columns in the periodic table are called groups (numbered from 1A to 8A or 1 to 18). Rows in the periodic table are called periods. Metals are located on the left hand side of the periodic table (most of the elements are metals). Non-metals are located in the top right hand side of the periodic table. Elements with properties similar to both metals and non-metals are called metalloids and are located at the interface between the metals and non-metals.

Reading the Periodic Table - The Basics Families or groups – vertical columns - have similar properties - contain the same outer electron configuration - show similar chemical behavior because it is the outer electrons involved in chemical reactions - 18 groups - Various ways of labeling and naming Roman numerals + letter (European) Arabic numerals + letter (American) Arabic numerals 1-18 (IUPAC)

The Periodic Table

The Periodic Table Some of the groups in the periodic table are given special names. These names indicate the similarities between group members: Group 1: Alkali metals. Group 2: Alkaline earth metals. Group 16: Chalcogens. Group 17: Halogens. Group 18: Noble gases.

Each period contains more and more elements Families and Groups (cont.) Representative or Main Group Elements = Groups 1,2 and 13-18 Transition metals = Groups 3-12 Inner transition elements (metals) = Element #’s 57-71 (Lantanides) and Element #’s 89-103 (Actinides) Periods = Horizontal rows #’d 1-7 Each period contains more and more elements

The Periodic Table with the Inner Transition Elements in Place

Metals tend to lose electrons! - Found on the left side of the periodic table Includes: All of groups 1 (except H) and 2, also Al (but not B) in group 13. All of the transition elements. The elements to the right of the transition elements The lanthanides and actinides (inner transition metals) Metals tend to lose electrons!

Metallic Properties: Luster: most metals have a silvery white “metallic” color because they reflect light of all wavelengths. Ductile, (capable of being drawn out into a wire) Malleable (can be hammered into thin sheets) Most semisolids @ room Tº High electrical conductivity & thermal conductivity - Examples: sodium, calcium, gold, aluminum

Nonmetals Found on the right side of the periodic table Nonmetals tend to gain electrons! Nonmetallic Properties: Poor reflectors of light, Hard or brittle, some are gases or soft solids Not malleable or ductile Do not conduct electricity, Poor conductor of heat - Examples: carbon, bromine, chlorine, sulfur

Diatomic Nonmetals Diatomic Molecules Nitrogen gas contains N2 molecules. Oxygen gas contains O2 molecules.

Metalloids or Semimetals Found along jagged line on table Metalloids lose or gain electrons depending on "who they're with!“ Mixture of both types of properties, or intermediate type Examples: B, Si, Ge, As, Sb, Te, At (the only metals on the solid "semimetal" line are Al and Po)

Information in an Element’s “Box” on the Periodic Table Atomic Number = the number of protons Atomic Mass = Weighted average of all of the isotopes of the element Mass number (for a particular isotope) = # protons + # o f neutrons. http://www.crystalgraphics.com/powerpictures/images.photos.asp?page=2&testing=0&qs=yes&ss=uranium&ipp=48&c=page&newflag=all

Introduction to the Modern Concept of Atomic Structure Comparing the Parts of an Atom

Comparing Subatomic Particles

Atomic Mass and Formula Mass To calculate the mass of a sample of atoms Each element exists as a mixture of isotopes Use a “weighted average” for the atomic mass Number on the bottom of each square in the periodic table is the average weight of all the isotopes of an element (in amu) All masses of other atoms are measured relative to carbon-12

Atomic Mass and Formula Mass Atomic masses are determined on a relative scale The standard scale references the carbon-12 isotope = 12.000 amu All other atomic masses are determined relative to carbon-12

Atomic Mass Units

Isotopes Isotopes are atoms with the same number of protons but different numbers of neutrons.

Isotopes A particular isotope is represented by the symbol. Only use this symbol when you know the number of neutrons exactly.

Na 22.99 Atomic Mass Listed on the periodic table Gives the mass of “average” atom of each element compared to 12C Average atom based on all the isotopes and their abundance % Atomic mass is not a whole number

Calculating Atomic Mass Percent(%) abundance of isotopes Mass of each isotope of that element Weighted average = mass isotope1(%) + mass isotope2(%) + … 100 100

Calculating #s’s of Subatomic Particles; Protons, Neutrons and Electrons The atomic number = the number of protons. If the atom is neutral, the number of electrons equals the number of protons Mass number of an isotope = Protons + Neutrons therefore Mass # - Atomic number = # neutrons.

16 31 65 8 15 30 More Atomic Symbols O P Zn 8 p+ 15 p+ 30 p+ 16 31 65 O P Zn 8 15 30 8 p+ 15 p+ 30 p+ 8 n 16 n 35 n 8 e- 15 e- 30 e-

Ions – Charged Particles Atoms can form ions by gaining or losing electrons. Metals tend to lose one or more electrons to form positive ions called cations.

Ions – Charged Particles Nonmetals tend to gain one or more electrons to form negative ions called anions.

Isotopes Cobalt - 59 Helium - 4 https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcTHz7dqYS1wSMjONCGFFjQ6adqoAI9YrcUgqzeQVoazzI2sWp8h-wqsONE http://www.expertsmind.com/CMSImages/883_calculate-nautron-number.png

Ions Ion Charges and the Periodic Table The ion that a particular atom will form can be predicted from the periodic table. Elements in Group 1 and 2 form 1+ and 2+ ions, respectively Group 7 atoms form anions with 1- charges Group 6 atoms form anions with 2- charges when compared to the neutral atoms Cations have fewer electrons than protons Anions have extra electrons (more) than protons

Common Monatomic Ions EOS