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Chapter Three

Chapter Three. Atomic Structure and the Periodic Table. Atomic Structure and the Periodic Table cont’d. Recall our understanding of an element. Element is matter that ______ be broken down into a simpler substance by ________ or _________ means. Recall our understanding of an atom.

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Chapter Three

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  1. Chapter Three Atomic Structure and the Periodic Table

  2. Atomic Structure and the Periodic Tablecont’d Recall our understanding of an element. Element is matter that ______ be broken down into a simpler substance by ________ or _________ means. Recall our understanding of an atom. Atom is the ________ particle of an element that can exist and still have the properties of the element.

  3. Atomic Structure and the Periodic Tablecont’d Now we will discuss ATOMIC STRUCTURE and Sub-Atomic Particles An atom is composed of a _______ and an area called the electron _____ • The nucleus is very small compared to the size of the atom • The nucleus contains the _______ (+) and the _______ • The __________ (-) are constantly moving around in the electron cloud • In a neutral atom, the number of electrons (-) is _______ to the number of protons (+)

  4. Atomic Structure and the Periodic Tablecont’d • Fig. 3.1Nuclear Model of the Atom The protons and neutrons of an atom are found in the central nuclear region, or nucleus, and the electrons are found in an electron cloud outside the nucleus.

  5. Atomic Structure and the Periodic Tablecont’d

  6. Atomic Structure and the Periodic Tablecont’d Atomic Symbols Charge = number of protons – number of electrons Mass number = number of protons + number of neutrons A Q X Z Atomic number = number of protons

  7. Atomic Structure and the Periodic Tablecont’d # _________ = Atomic Number Z Atoms have no charge, # __________ = # __________ = Z # Neutrons = ______ Number (A) - # _________ (Z)

  8. Atomic Structure and the Periodic Tablecont’d Electrons are arranged around the nucleus of an atom Electrons can be _____ to, _______ from or _______ with other atoms When lost or gained, atoms become _______ (ions) Lost electrons result in _____charged ion, ________ Gained electrons result in _____ charged ion, _____ # Protons in nucleus ________ changes, _________ arrangement determine chemical properties

  9. Atomic Structure and the Periodic Tablecont’d Atomic Symbol vs Periodic Table 20 Ca 40.08 40 2+ Ca 20

  10. Atomic Structure and the Periodic Tablecont’d • How many electrons, neutrons, and protons are in the following particles?

  11. Atomic Structure and the Periodic Tablecont’d # Protons remains constant # Neutrons can vary Mass numbers of atoms of same element will vary depending on the # neutrons in the nucleus Atoms that differ in # neutrons are called Isotopes

  12. Atomic Structure and the Periodic Tablecont’d Most elements have naturally occurring __________ Number of isotopes can range from two to ten Example: Silicon, Si exists in three isotopic forms All Si atoms have 14 protons and 14 electrons Most, 92.21% contain 14 neutrons Some, 4.70% contain 15 neutrons Some, 3.09% contain 16 neutrons

  13. Atomic Structure and the Periodic Tablecont’d They have the following notations 28 29 30 Si Si Si 14 14 14

  14. Atomic Structure and the Periodic Tablecont’d The additional neutrons in the nucleus may have very slight effects on the chemical properties of the element, and some measurable effects on some physical properties such as melting points, boiling points and Densities. See Chemical Connections on pg 55 in text.

  15. Atomic Structure and the Periodic Tablecont’d The atomic mass is expressed in atomic mass units amu • atomic mass unit • Defined as 1/12th the mass of 12C • 1 amu = the mass of 1 proton or 1 neutron The atomic mass that is found on the periodic table or used for calculations is a weighted average of the atomic masses for the isotopes

  16. Atomic Structure and the Periodic Tablecont’d • To get the average mass of an element, you must add together the mass contributions of each different isotope • % abundance x isotopic mass = mass contribution • Calculate the average atomic mass of Chlorine if 75.53% of the atoms are 35Cl (34.97 amu) and 24.47% of the atoms are 37Cl (36.97 amu). (0.7553 x 34.97 amu) + (0.2447 x 36.97 amu) = 35.46 amu

  17. Atomic Structure and the Periodic Tablecont’d

  18. Atomic Structure and the Periodic Tablecont’d • Table 3.2 Isotopic Data for Elements with Atomic Numbers 1 through 12

  19. Atomic Structure and the Periodic Tablecont’d Early 1800s, scientists searched for some order in the chemical information known at that time Certain elements had properties that were very similar to those of other elements Method or Arrangement was sought that would be consistent with this information

  20. Atomic Structure and the Periodic Tablecont’d John Newlands (1865) Arranged elements in order of increasing atomic mass When he did this, he noticed that there were chemical and physical properties that repeated every eight elements “law of octaves”

  21. Atomic Structure and the Periodic Tablecont’d • Fig. 3.2 Mendeleev constructed a periodic table as part of his effort to systemize chemistry. Edgar Fahs Smith Collection, University of Pennsylvania Library

  22. Atomic Structure and the Periodic Tablecont’d Dmitri Mendeleev and Julius Lothar Meyer independently proposed ideas or relationships regarding the periodicity of __________ and increasing atomic ________ or atomic _________. Modern Periodic Law states that when elements are arranged in order of increasing atomic number, elements with similar chemical properties occur at periodic or regularly recurring intervals.

  23. Atomic Structure and the Periodic Table • CO 3.1 Music consists of a series of tones that build octave after octave. Similarly, elements have properties that recur period after period. Novastock/PhotoEdit

  24. Atomic Structure and the Periodic Tablecont’d Elements with similar chemical properties are positioned in _________ ___________ These _________ _________ are called ________ The ____________ ______ of elements are called ____________ Note the _________ are numbered sequentially 1-7 The ________ are identified by two notations, using Roman numerals and letters, or numbered sequentially 1-18

  25. Atomic Structure and the Periodic Tablecont’d Also note that Element 72 follows Element 57, as does Element 104 follows Element 89 The missing elements 58 through 71 and 90 through 103 are located in two rows at the bottom of the periodic table. Positioned here for convenience. See the periodic table in the next slide with these rows positioned where they should be located.

  26. Atomic Structure and the Periodic Tablecont’d Fig. 3.4 In this periodic table, elements 58 through 71 and 90 through 103 are shown in their proper positions.

  27. Atomic Structure and the Periodic Tablecont’d Common Names for some Groups Group IA – Alkali Metals, excluding H Soft, shiny and readily react with water Group IIA – Alkaline earth metals Soft, shiny and moderately reactive toward water Group VIIA – Halogens Reactive, colored, gases at or slightly above room temperatures Group VIII – Nobel Gases Generally unreactive, that undergo few, if any, chemical reactions

  28. Atomic Structure and the Periodic Tablecont’d

  29. Atomic Structure and the Periodic Tablecont’d • Some familiar metals are aluminum, lead, tin, and zinc. Fig. 3.5 (b) Some familiar nonmetals are sulfur, phosphorus, and bromine.

  30. Atomic Structure and the Periodic Tablecont’d • Fig. 3.6 This portion of the periodic table shows the dividing line between metals and nonmetals.

  31. Atomic Structure and the Periodic Tablecont’d Electrons are arranged around the nucleus of an atom Electrons can be lost to, gained from or shared with other atoms When lost or gained, atoms become charged (ions) Lost electrons result in + charged ion, cation Gained electrons result in – charged ion, anion Inference: Electrons are special and we will learn are related to the chemical properties of an element

  32. Atomic Structure and the Periodic Tablecont’d • The space outside the nucleus in an atom is called the ___________ ____________ • The _________ ________ is subdivided into different ___________ (positioned according to energy each electron possesses • Shells are subdivided into ____________ • Subshells are subdivided into __________ • Each orbital contains _____ electrons

  33. Atomic Structure and the Periodic Tablecont’d • Electron Shell • A region of space about a nucleus that contains electrons that have approximately the same energy and that spend most of their time approximately the same distance from the nucleus • 1st shell • Can contain up to 2 electrons • 2nd shell • Can contain up to 8 electrons • 3rd shell • Can contain up to 18 electrons • 4th shell • Can contain up to 32 electrons • Any shell can contain up to 2n2 electrons, where n is the shell number

  34. Atomic Structure and the Periodic Tablecont’d • Subshell • A region of space within an electron shell that contains electrons that have the same __________ • Four different kinds of subshells: s, p, d, and f • Shell 1: contains s subshell • Shell 2: contains s and p subshells • Shell 3: contains s, p, and d subshells • Shell 4: contains s, p, d, and f subshells

  35. Atomic Structure and the Periodic Tablecont’d • Fig. 3.7 The number of subshells within a shell is equal to the shell number.

  36. Atomic Structure and the Periodic Tablecont’d • Orbital • Region of space where two electrons are found • Have different shapes depending on which subshell they are in (shape of region of space not electrons) • There are a different number of orbitals in each kind of subshell • In an s subshell, there is 1 orbital • In a p subshell, there are 3 orbitals • In a d subshell, there are 5 orbitals • In a f subshell, there are 7 orbitals

  37. Atomic Structure and the Periodic Tablecont’d Fig. 3.8 An s orbital has spherical shape; a p orbital has two lobes; a d orbital has four lobes; and an f orbital has eight lobes.

  38. Atomic Structure and the Periodic Tablecont’d Fig. 3.9 Orbitals within a subshell differ mainly in orientation.

  39. Atomic Structure and the Periodic Tablecont’d • There are ____ electrons in each ________ • The electrons move around in the __________ • One of the electrons spins __________ • One of the electrons spins ______________________

  40. Atomic Structure and the Periodic Tablecont’d • Electron configurations tells us in which subshells the electrons for an element are located. • Three rules: • 1. Electrons fill orbitals starting with lowest energy first • 2. There can be no more than 2 electrons in any orbital, and those electrons must have different spins • 3. For orbitals in the same subshell, electrons fill each orbital singly before any orbital gets a second electron

  41. Atomic Structure and the Periodic Tablecont’d • Fig. 3.10 The order of filling various electron subshells. Subshells of different shells “overlap.” How will you remember the order?

  42. Atomic Structure and the Periodic Tablecont’d • Fig. 3.11 The order of filling various electron subshells with electrons follows the same order given by the arrows in this diagram.

  43. Atomic Structure and the Periodic Tablecont’d Writing Electronic Configurations H 1s1 He 1s2 Li 1s2, 2s1 Ne 1s2, 2s2, 2p6 Na 1s2, 2s2, 2p6, 3s1 Ar 1s2, 2s2, 2p6, 3s2, 3p6 K 1s2, 2s2, 2p6, 3s2, 3p6, 4s1 K [Ar] 4s1 Kr 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p6 Kr [Ar] 4s2, 3d10, 4p6

  44. Atomic Structure and the Periodic Tablecont’d Electronic Configurations of Transition Elements Fe 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d6 Br 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p5 Pb 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p6, 5s2, 4d10, 5p6, 6s2, 4f14, 5d10, 6p2

  45. Atomic Structure and the Periodic Tablecont’d • Which of the following electron configurations is correct for • A)   • B)   • C)   • D)   • E)  

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