Chemistry Chapter 5the Periodic Table • In 1860, Stanislao Cannizzaro presented a method for accurately measuring the relative atomic masses of the elements.
Chemistry Chapter 5The Periodic Law • In 1869, Dmitri Mendeleev published his first “periodic table”. • He started by placing the known elements in order using their atomic masses. • He recognized that certain properties repeated themselves “periodically”. • He then rearranged the elements so that elements with similar properties appeared together in his table. • His procedure left empty spaces for elements that had not been discovered.
Moseley & the Periodic Law • In 1911, Henry Moseley discovered that the periodic table fit better when the elements were placed in order according to their increasing positive charge. • This led to the principle of chemical periodicity known as the: • periodic law- The physical and chemical properties of the elements are periodic functions of their atomic numbers.
The Modern Periodic Table • The periodic table is an arrangement of the elements in order of their atomic numbers so that elements with similar properties fall in the same column, or group. • group (or family)- the vertical columns of the periodic table • period- the horizontal rows of the periodic table
The Modern Periodic Table • noble gases- the group 18 elements which are not reactive (inert) • lanthanides (rare earth elements)- elements 58-71 at the bottom of the periodic table that are very similar in properties and represent the 4th energy level “f” orbital block elements from period 6. • actinides- elements 90-103 are all radioactive and represent the 5th energy level “f” orbital block elements from period 7. • Do section review #3 & 5 on page 137.
Section Review- page 137 3- The noble gases, the lanthanides , and the actinides have been added. They were not yet discovered when Mendeleev wrote the original periodic table and he had no way of predicting their existence. 5- The periodic table is arranged according to atomic number, not atomic mass. The average atomic mass on the periodic table is the weighted average of the isotopes of an element and some elements have large percentages of heavy isotopes.
Electron Configuration & the Periodic Table • s-block elements- are groups #1 & #2 in which a single “s” orbital is being filled in the energy level equal to the period number. • alkali metals- are the group #1 metals that are so reactive that they do not exist as pure elements in nature • alkaline-earth metals- are the group #2 metals that also are very reactive and do not exist alone in nature • Do problem #1 on page 143.
Practice problem page 143 1- What is the period, group and block of [Kr]5s1 ? [Kr]5s1 tells us the element rubidium is in the: 5th period 1st group s-block
Electron Configuration & the Periodic Table • p-block elements- are groups #13-#18 in which 3 “p” orbitals are being filled in the energy level equal to the period number. • halogens- are the group 17 elements • noble gases- are the group 18 elements that are non-reactive (inert) • Do practice problems #1 & 2 on page 148.
Practice problems page 148 1a- Write the outer electron configuration of the group 17 element in the 3rd period. 3s23p5 1b- Identify the element and identify it as a metal, metalloid, or nonmetal. chlorine (Cl) nonmetal
Practice problems page 148 2a- What is the period, block and group of the element [Ar]3d104s24p3 ? period 4 p-block group 15 (5A) 2b- What is the name of the element and is it a metal, metalloid or nonmetal? arsenic (As) is a metalloid
Electron Configuration & the Periodic Table • d-block elements (transition metals)- group #3-#12 elements in which 5 “d” orbitals are being filled in the energy level equal to the period # minus 1. • They are metals that have typical metallic properties. • Do practice problems #1 & 2 on page 146.
Practice problems page 146 1- What is the period, group, & block of the element [Ar]3d84s2 ? period 4 group 10 d block 2- What is the electron configuration of the element in group 12 of the fifth period? [Kr]4d105s2
Electron Configuration & the Periodic Table • f-block elements- are the two rows at the bottom of the periodic table that represent 7 “f” orbitals being filled in the energy level that is equal to the period number minus 2 • lanthanides- elements # 58-71 that are also called the rare earth elements • actinides- elements #90-103 that are all radioactive • elements 93(neptunium) through 103 (lawrencium) are all man-made and do not occur naturally
Questions • Do Practice problem #1 on page 149. • Do Section Review problems #2, 4, & 5.
Practice problem on page 149 For each of the following identify the block, period, group, group name, element name, element type, and relative reactivity. 1a- [He]2s22p5 p-block, period 2, group 17, halogen, fluorine (F), nonmetal, & highly reactive 1b- [Ar]3d104s1 d-block, period 4, group 11, transition metal, copper (Cu), metal, & low reactivity
Section review page 149 2a- group 1 is the alkali metals b- group 2 is the alkaline earth metals c- groups 3-12 are the transition metals d- group 17 is the halogens e- group 18 is the noble gases 4- noble gas electron configuration of the group 15 period 4 element [Ar]3d104s24p3 5- period, block, & group of [Ar]3d74s2 period 4, d-block, group 9
Electron Configuration & Periodic Properties • atomic radius- one-half the distance between the nuclei of identical atoms that are bonded together. • As you go across a period, the positive charge of the nucleus increases across a period, the pull exerted on the electron cloud increases and the atomic radius of the elements decreases across the period. • As you move down a group, each successive element adds an energy level so the atomic radii increase down a group.
Electron Configuration & Periodic Properties • ion- an atom or group of atoms that has a positive or negative charge ionization- any process that results in the formation of an ion
ionization energy- the amount of energy required to remove one electron from a neutral atom of an element • ionization energies of the main group elements increase across a period • ionization energies of the main group elements usually decrease down a group
Electron Configuration & Periodic Properties • electron affinity- the energy change that occurs when an electron is acquired by a neutral atom • cation- an ion with a positive charge due to the loss of electrons • anion- an ion with a negative charge due to the gain of electrons
Electron Configuration & Periodic Properties • valence electrons- the electrons available to be gained, lost, or shared by atoms in the formation of chemical bonds to make compounds
electronegativity- a measure of the ability of an atom in a chemical compound to attract electrons from another atom in the compound • electronegativity tends to increase across a period and either decrease or remain the same down a group • fluorine (F) is the most electronegative of the elements.
Chapter 5 Review • Chapter Review problems pages 166-168 #1, 2, 8, 9, 11, 13, 17, 18, 19, 22, 23, 28, 32, & 40.
Chapter 5 Test Review Exercise 1- Which elements are called: a- alkali metals b- alkaline earth metals c- transition metals d- halogens e- noble gases f- lanthanides g- actinides 2- What were the major contributions of: a- Dmitri Mendeleev b- Henry Moseley
3- What is the period number, group number, block, & identity of the element designated [Kr]4d105s25p5 4- What are valence electrons and where are they found? 5- What are the period and group trends for the atomic radius of the elements?
Helpful Hints- Periodic Table Lab • Make note that the sets of elements on page one are in groups (vertical columns). • The table is for the “s” and “p” blocks ONLY, no “d” or “f” block elements are included. • The clues given are for periods 1 through 4 ONLY. • The formulas of oxides always end with the element oxygen. • The elements that are liquid at room temperature are written in blue on the table at the front of the room. • The “outer energy level” includes “s” & “p” orbitals ONLY. • The elements that are gas at room temperature are written in red on the table at the front of the room. • The metalloids include B, Si, Ge, As, Sb, & Te. • Periods 5 & 6 (AA-PP) will be filled out using page 3 of the lab. Match the element properties with those on appendix A.
Chemistry Chapter 5 Vocabulary QuizMonday 11/7/2011 Dmitri Mendeleev periodic law periodic table group period noble gases lanthanides actinides alkali metals alkaline-earth metals halogens d-block elements atomic radius ionization ionization energy electronaffinity cation anion valence electrons electronegativity
Chemistry Chapter 5 Test Review 25 multiple choice questions: • Mendeleev & his 1st periodic table • Definitions, locations, & properties of lanthanides, actinides, noble gases, halogens, alkali metals, alkaline earth metals, & transition metals • Definitions of periodic law, groups, periods, atomic radius, electronegativity, cation, anion, & valence electrons • Where are valence electrons located? • Period & group trends for atomic radius • What form do alkali metals take in nature? • Determine the number of valence electrons for different groups
Honors Chemistry Chapter 5 Test Review 35 multiple choice questions worth two points each. • Know the definition and inventor (Mendeleev) of the first periodic table and how he arranged the elements. • Know how the modern periodic table is arranged and what groups of elements have been added to it. • Know the groups and names and unique properties of the alkali metals, alkaline earth metals, halogens, noble gases, transition metals, lanthanides, and actinides. • Know the definition of the periodic law, periods, groups. • Identify the period & group for a specific element. next slide
Know the general location of the metals, metalloids, & nonmetals on the periodic table. • Why is hydrogen often placed away from the body of the group 1 elements on a periodic table? • Know where the s, p, d, & f block element are located and their meaning. • Know the definitions of ionization energy, electronegativity, and atomic radius and their trends both across a period and down a group. • Know the definition of valence electrons & how to find their number in s & p groups.