Chapter 3 Atomic Structure How are the elements organized? By the Periodic Table a. Groups - all elements have similar properties in a group b. Periods - 7 periods - period # tells the # of energy levels

Regions of the Periodic Table 1.Metals Good conductors of heat and electricity malleable- can be hammered into thin sheets Ductile- can be stretch into thin wire Luster- shiny High melting point

Regions con. 2.Nonmetals Poor conductors of heat and electricity Brittle Dull Not malleable Not ductile Low melting point

Regions con. 3.Metalloids have properties of both B, Si, Ge, As, Sb, Te 4.Noble Gases Inert(unreactive) gas at room temperature

What characteristics of an element can be determined from the Periodic Table? Atomic # Atomic mass Symbol State of matter Period # Group # Metal, nonmetal, metalloid, noble gas Properties of metals, nonmetals # of protons, neutrons, electrons

Basic Structure of an Atom A. Atomic Models 1. Dalton’s Atomic Theory a. All matter is composed of atoms b. Atoms of a given element are the same c. Atoms of different elements are different d. Atoms of different elements combine in simple whole # ratios e. Atoms cannot be divided, created,or destroyed

Models con. 2. J.J. Thomson-1897 credited with discovering the electron often referred to as the “Plum Pudding” Model  ball of positive charge with negative charged electrons embedded inside 3.Ernest Rutherford-1911 credited with discovering the nucleus  dense positively charged center with electrons moving around the nucleus marble in a baseball stadium

Models con. 4.Niels Bohr electrons reside in energy levels to go to a higher energy level you need energy  Quantum- amount of energy needed to jump to a higher level Ground State- electrons in lowest possible energy level Excited State- electrons boosted to higher energy level

Models con. 5.James Chadwick credited with discovering the neutron 6.Quantum Theory based on wave mechanics based on the probability of finding an electrons in a certain position  Orbital Orbital- area of high probability contains up to 2 electrons exact location of electrons cannot be determined

B. Parts of an Atom 1. Proton positive charge located in the nucleus Atomic Number- # of protons in the nucleus

Parts con. 2.Neutron- no charge Isotope- atoms with different # of neutrons How do we write Isotopes? 2 ways a. Name-mass #(P + N) Hydrogen-1, Hydrogen-2, Hydrogen-3 b. Symbol,Mass #(superscript), Atomic #(subscript)

Parts con. 3.Electrons- negative charge located in the electron cloud How do we label electrons according to the Quantum Theory? each electron is assigned a set of 4 numbers

Quantum Numbers 1 st Quantum #  Principal Quantum # represented by the symbol “n”= energy level as the energy increase, “n” increases 2 nd Quantum #  Angular Momentum Quantum # represented by the symbol “ l ”  indicates the shape of the orbital(sublevel)

2nd Quantum # con. Orbital Letter Designations according to values of l l Letter 0s 1p1p 2d2d 3f3f Each energy level consist of sublevels # of sublevels = # of energy levels s.htm

Quantum con. 3 rd Quantum #  Magnetic Quantum # represented by the symbol “ m l ”  any integer from – l to +l determines the orientation in space of an electron cloud 4 th Quantum #  Spin Quantum # represented by the symbol “ m s ” has only 2 values, +½(  ) or -½(  )

Electron Configurations The arrangement of electrons in an atom Rules Governing Electron Configurations 1. Aufbau Principle- electrons fill orbitals that have the lowest energy first 1s  2s  2p  3s  3p  4s  3d 2. Pauli Exclusion Principle-an orbital can hold 2 electrons of opposite spin 3. Hund’s Rule- orbitals of each sublevel are filled with 1 electron before pairing of electrons occur

How are electron configurations represented? A.Orbital Diagram- shows the distribution in the sublevels and the direction of spin - each orbital is represented by a box or line - each box/line is labeled with the principal quantum # and the sublevel B.Electron configuration notation- shorthand form of the orbital diagram C.Noble Gas Notation- uses the previous noble gas and the electrons in the outer shell

Chapter 4 Who invented the Periodic Table? Dmitri Mendeleev, 1869 He arranged the elements in order of increasing atomic mass What 20 th century scientist made a discovery with the Periodic Table? Henry Mosely Arranged the elements in order of increasing atomic number

The Periodic Law The physical and chemical properties of the elements are periodic functions of their atomic number or When elements are arranged in order of increasing atomic number, elements with similar properties appear at regular intervals

How do we know that the Periodic Law is true? Family Characteristics Group 1 or IA- Alkali Family -soft, highly reactive metals  stored in oil to protect from moisture - has 1 valence electron( electrons in the outermost energy level) Group 2 or IIA- Alkaline Earth Family - harder, denser, stronger, and higher melting point than alkali family has 2 valence electrons

Families con. Groups 3-12 Transition Elements( d and f blocks) -good conductors, high luster Lanthanides- elements fills 4f orbital Actinides- elements fills the 5f orbital - all are radioactive, most are man-made

Families Groups properties vary -contains metals and nonmetals Group 17/VIIA Halogen Family - most reactive nonmetal elements -combine with metals to form salts -have 7 valence electrons

Families Group 18 or VIIIA Noble Gases -inert gases -very low reactivity - outer energy level is complete Hydrogen -forms its own family -Most common element in the universe -Highly reactive

Periodic Trends 1.Atomic radius Group trend- atomic radius increases, Why? -adding an energy level Period trend- atomic radius decreases from left to right, Why? - from left to right, the number of protons and electrons are increasing which means that the force of attraction is also greater

Trends 2.Ionization Energy- the energy required to remove one electron from a neutral atom Ion- charged atom G.T.- in general,ionization energy decreases down a group P. T.- ionization energy increases across a period

Trends 3.Electron Affinity- the energy change that occurs when an electron is acquired by a neutral atom G.T.- decreases within a group P.T.- increases within a period 4.Electronegativity- a measure of the ability of an atom in a chemical compound to attract electrons G.T.- decreases within a family P.T.- increases within a period

Relating Mass to Numbers of Atoms 1.Mole- SI unit for amount of substance 2.Avogadro’s Number- the number of particles in exactly one mole of a pure substance = x particles 1 mol of eggs = x eggs 3.Molar Mass- the mass of one mole of a pure substance g/mol = the atomic mass of the element/ compound

Why are these concepts important? Examples How many atoms are in 2.5 moles of silicon? Convert 3.01 x atoms of silicon to moles of silicon? How many atoms are present in 3.7 moles of Na? How many moles of Xenon are equal to 5.66 x atoms of Xenon?

More Conversion Problems Determine the moles in 237 g of copper atoms. Find the mass in grams of 8.6 moles of bromine atoms? Find the mass in grams of 7.55 moles of silicon atoms. How many moles are in 38 grams of carbon atoms?

Review Game 1.Name an element in the 4 p orbital? 2.What is the principal quantum # of Radon? 3.Name a halogen that has a principal quantum # of 4. 4.The atomic # of Tin is? 5.The elements in group 1 are called? 6.How many electrons are found in the halogen gas with 5 energy levels?

Con. 7.The s orbital has a quantum # of? 8.The last electron of cadmium is found in which orbital? What is its spin? 9.Draw the orbital diagram of Ge. 10.What is the electron configuration of Po using the Noble Gas configuration?