Copyright © Houghton Mifflin Company. All rights reserved.3–13–1 3.1 Internal Structure of an Atom Atoms were thought to be indivisible In about 1900, it was learned that all atoms release negatively charged particles (electrons). If there are negative particles, there must be positive particles (protons).

Copyright © Houghton Mifflin Company. All rights reserved.3–23–2 3.1 Internal Structure of an Atom To make mass relationships work, there had to be neutral particles with about the same mass as protons (neutrons).

Copyright © Houghton Mifflin Company. All rights reserved.3–33–3 Charge and Mass Characteristics of Electrons, Protons, and Neutrons ParticleMass(amu)Charge electron –1 proton neutron

Copyright © Houghton Mifflin Company. All rights reserved.3–43–4 Figure 3.1 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.

Copyright © Houghton Mifflin Company. All rights reserved.3–53–5 3.2 Atomic Number and Mass Number # of Protons = Z = Atomic Number # of Protons identifies the element # Above element symbol on Periodic Table # of Electrons = Z for neutral atom “Protons give an element its identity, electrons give it its personality” Darryl Ebbing to Bill Bryson

Copyright © Houghton Mifflin Company. All rights reserved.3–63–6 3.2 Atomic Number and Mass Number Mass # = # of Protons + # of Neutrons # of Neutrons = Mass # - # of Protons

Copyright © Houghton Mifflin Company. All rights reserved.3–73–7 3.3 Isotopes and Atomic Masses It is possible for atoms of the same element to have different numbers of neutrons. These variants on an element are called isotopes.

Copyright © Houghton Mifflin Company. All rights reserved.3–83–8 3.3 Isotopes and Atomic Masses

Copyright © Houghton Mifflin Company. All rights reserved.3–93–9 3.3 Isotopes and Atomic Masses Symbols for isotopes of an element: H H H C C C ProtiumCarbon-12 DeuteriumCarbon-13 Tritium*Carbon-14*

Copyright © Houghton Mifflin Company. All rights reserved.3– Isotopes and Atomic Masses The atomic mass of an element is a weighted average of the masses of the isotopes, on a relative scale. Carbon-12 is defined to have a mass of exactly 12 atomic mass units (amu).

Copyright © Houghton Mifflin Company. All rights reserved.3– Isotopes and Atomic Masses Atomic Mass of Chlorine: 75.53% of chlorine atoms are Chlorine 35, atomic mass = amu 24.47% of chlorine atoms are Chlorine 37, atomic mass = amu

Copyright © Houghton Mifflin Company. All rights reserved.3– Isotopes and Atomic Masses Atomic Masses are given below the element’s symbol on the Periodic Table

Copyright © Houghton Mifflin Company. All rights reserved.3–13 Chemistry at a Glance: Atomic Structure

Copyright © Houghton Mifflin Company. All rights reserved.3– The Periodic Law and the Periodic Table

Copyright © Houghton Mifflin Company. All rights reserved.3–15 Dmitri Mendeleev

Copyright © Houghton Mifflin Company. All rights reserved.3–16 The modern Periodic Table. Elements with similar chemical properties fall in the same vertical column.

Copyright © Houghton Mifflin Company. All rights reserved.3–17 Figure 3.4 In this periodic table, elements and 90 through 13 (in color) are shown in their proper positions.

Copyright © Houghton Mifflin Company. All rights reserved.3– Metals, Nonmetals, etc. Group (family) of elements --vertical column Period (row) of elements--horizontal row Group 1A metals:alkali metals Group 2A metals: alkaline earth metals Groups 1A – 8A: representative elements Groups 1B – 8B: transition metals Group 7A: halogens Group 8A: noble gases

Copyright © Houghton Mifflin Company. All rights reserved.3–19 Properties of Metals, Metalloids, and Nonmetals.

Copyright © Houghton Mifflin Company. All rights reserved.3– Electron Arrangement Within Atoms Shells: Regions of space that contain electrons with about the same energy Numbered 1, 2, 3, 4 Correspond to rows on Periodic Table Subshells: Regions of space within an electron shell that contain electrons with exactly the same energy s, p, d, and f subshells Correspond to regions on Periodic Table

Copyright © Houghton Mifflin Company. All rights reserved.3–21 Figure 3.7 The number of subshells within a shell is equal to the shell number, as shown here for the first four shells. Each individual subshell is denoted with both a number (its shell) and a letter (the type of subshell it is in).

Copyright © Houghton Mifflin Company. All rights reserved.3–22 Figure 3.8 An s orbital has a spherical shape A p orbital has two lobes A d orbital has four lobes An f orbital has eight lobes.

Copyright © Houghton Mifflin Company. All rights reserved.3–23 Figure 3.9 A summary of the interrelationships among shells, subshells, and orbitals for the first four shells.

Copyright © Houghton Mifflin Company. All rights reserved.3–24 Figure 3.10 The order of filling of various electron subshells is shown on the right-hand side of this diagram. Above the 3p subshell, subshells of different shells "overlap".

Copyright © Houghton Mifflin Company. All rights reserved.3–25 Figure 3.11 The order for filling electron subshells with electrons follows the order given by the arrows in this diagram. Start with the arrow at the top of the diagram and work toward the bottom of the diagram, moving from the bottom of one arrow to the top o the next-lower arrow.

Copyright © Houghton Mifflin Company. All rights reserved.3–26 3.7, 3.8 Electron Configurations And the Periodic Table Elements within a family (group) have the same properties because their electron configurations are similar. Elements in a family have the same number of electrons in their outermost (valence) shells.

Copyright © Houghton Mifflin Company. All rights reserved.3–27 Figure 3.12 Electron configurations and the positions of elements in the periodic table.

Copyright © Houghton Mifflin Company. All rights reserved.3– Nuclear Chemistry Stable Nuclei: Do not change readily a.k.a. stable isotopes Radioactive Nuclei: Undergo radioactive decay a.k.a. radioisotopes Are transformed into different elements as part of radioactive decay

Copyright © Houghton Mifflin Company. All rights reserved.3– Nuclear Chemistry

Copyright © Houghton Mifflin Company. All rights reserved.3– Half-Life Decay of 80.0 mg of Iodine-131, t 1/2 = 8.0 days.

Copyright © Houghton Mifflin Company. All rights reserved.3–31 Properties of Some Radionuclides.

Copyright © Houghton Mifflin Company. All rights reserved.3– Types of Radioactivity Table 3.4 Characteristics of the Three Most Common Types of Radiation Given off by Radioactive Atoms.

Copyright © Houghton Mifflin Company. All rights reserved.3– Radioactive Decay Equations (XI-1) Sum of A’s (mass numbers) and Z’s (atomic numbers) on each side of the equation must be equal.

Copyright © Houghton Mifflin Company. All rights reserved.3–34 Alpha (  ) Emission Helium Nucleus (  particle) is Ejected

Copyright © Houghton Mifflin Company. All rights reserved.3–35 Beta (  ) Emission Electron (  particle) is Ejected

Copyright © Houghton Mifflin Company. All rights reserved.3–36 Gamma (  ) Emission No change in nucleus  Rays usually accompany other emissions Release of energy

Copyright © Houghton Mifflin Company. All rights reserved.3–37 Positron (  1+ ) Emission Positively charged electron is emitted A cyclotron is used to produce F-18

Copyright © Houghton Mifflin Company. All rights reserved.3– Biological Effects of Radiation Called “Ionizing Radiation” Knocks electrons out of their proper places Produces reactive species where they don’t belong Effect is similar to burning but penetrates more deeply than heat

Copyright © Houghton Mifflin Company. All rights reserved.3–39 Figure 3.15 Alpha, beta, and gamma radiations differ in penetrating ability.

Copyright © Houghton Mifflin Company. All rights reserved.3–40 Dose Effects REM = Roentgen Equivalent in Man 1 Roentgen  1.8 x Ion Pairs gram of tissue

Copyright © Houghton Mifflin Company. All rights reserved.3– Nuclear Medicine Diagnostic Use: Tracers – “Make Noise” A radioisotope will do the same chemistry as a stable isotope, can be used to see if some- thing is behaving normally

Copyright © Houghton Mifflin Company. All rights reserved.3–42 Properties of Radionuclides for Diagnoses Short half-life (just long enough to prepare and administer) Stable, nontoxic “daughters”  -Emitter so radiation gets out (  and  just burn) Reactivity with diseased tissue “hot spot” or “cold spot”

Copyright © Houghton Mifflin Company. All rights reserved.3– Nuclear Medicine Therapy: “Hurt Something” The radioisotope should get to target organ or tumor and emit radiation that destroys

Copyright © Houghton Mifflin Company. All rights reserved.3–44 Properties of Radionuclides for Therapy Short half-life (just long enough to prepare and administer) Stable, nontoxic “daughters”  or  -Emitter to burn in concentrated area (  isn’t localized enough) Reactivity with diseased tissue “hot spot” not “cold spot”

Copyright © Houghton Mifflin Company. All rights reserved.3–45 Other Medically Important Radiation X-rays Slightly lower energy than  -rays Produced by beaming  -particles on metal Heavy elements are opaque to x-rays although they are not radioactive Iodine, Barium

Copyright © Houghton Mifflin Company. All rights reserved.3–46 Other Medically Important Radiation MRI (Magnetic Resonance Imaging) Magnetic field and radio-frequency beam Not ionizing, very low energy Can see water in tissue; hydrogen is active nucleus

Copyright © Houghton Mifflin Company. All rights reserved.3–47 Other Medically Important Radiation Ultrasound High frequency sound energy Not ionizing, very low energy Looks for echoes, sound bounces off hard or stiff surfaces