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Electrons in Atoms and the Periodic Table

Electrons in Atoms and the Periodic Table
Chapter 9 Electrons in Atoms and the Periodic TableClassical View of the Universe • Since the time of the ancient Greeks, the stuff of the physical universe has been classified as either matter or energy. • Matter is has to have mass and volume • Energy, is not composed of particles. • Energy can only travel in waves. www.ThesisScientist.comThe Nature of Light—Its Wave Nature • Light is a form of electromagnetic radiation. • Electromagnetic radiation is made of waves called photons; traveling at ―c‖ • Electromagnetic radiation moves through space like waves move across the surface of a pond www.ThesisScientist.comSpeed of Energy Transmission www.ThesisScientist.comElectromagnetic Waves • Every wave has four characteristics that determine its properties: wave speed, height (amplitude), length, number of wave peaks that pass in a given time. • All electromagnetic waves move through space at the same, constant speed. 8 3.00 x 10 meters per second in a vacuum = The speed of light, c. www.ThesisScientist.comCharacterizing Waves • The amplitude is the height of the wave.  The distance from node to crest.  The amplitude is a measure of how intense the light is—the larger the amplitude, the brighter the light. • The wavelength (l) is a measure of the distance covered by the wave.  The distance from one crest to the next. Or the distance from one trough to the next, or the distance between alternate nodes. It is actually one full cycle, 2π  Usually measured in nanometers. 9 1 nm = 1 x 10 m www.ThesisScientist.comElectromagnetic Waves www.ThesisScientist.comCharacterizing Waves • The frequency (n) is the number of waves that pass a point in a given period of time. The number of waves = number of cycles. 1 Units are hertz (Hz), or cycles/s = s . 1 1 Hz = 1 s • The total energy is proportional to the amplitude and frequency of the waves. The larger the wave amplitude, the more force it has. The more frequently the waves strike, the more total force there is. www.ThesisScientist.comLow Frequency Wave l l High Frequency Wave l www.ThesisScientist.comThe Electromagnetic Spectrum • Light passed through a prism is separated into all its colors. This is called a continuous spectrum. • The color of the light is determined by its wavelength. www.ThesisScientist.comColor • The color of light is determined by its wavelength.  Or frequency. • White light is a mixture of all the colors of visible light.  A spectrum.  RedOrangeYellowGreenBlueViolet. • When an object absorbs some of the wavelengths of white light while reflecting others, it appears colored.  The observed color is predominantly the colors reflected.  Called transmitted light www.ThesisScientist.comTypes of Electromagnetic Radiation • Classified by the Wavelength Radiowaves = l 0.01 m. Low frequency and energy. 4 2 Microwaves = 10 m l 10 m. 7 5 Infrared (IR) = 8 x 10 l 10 m. 7 7 Visible = 4 x 10 l 8 x 10 m. ROYGBIV. 8 7 Ultraviolet (UV) = 10 l 4 x 10 m. 10 8 Xrays = 10 l 10 m. 10 Gamma rays = l 10 . High frequency and energy. www.ThesisScientist.comElectromagnetic Spectrum www.ThesisScientist.comParticles of Light th • Scientists in the early 20 century showed that electromagnetic radiation was composed of particles we call photons. Max Planck and Albert Einstein. Photons are particles of light energy. • One wavelength of light has photons with that amount of energy. www.ThesisScientist.comThe Electromagnetic Spectrum and Photon Energy • Short wavelength light have photons with highest energy = High frequency Radio wave photons have the lowest energy. Gamma ray photons have the highest energy. • Highenergy electromagnetic radiation can potentially damage biological molecules. Ionizing radiation The waves fit between atomatom bonds, and vibrate/shake the atoms loose www.ThesisScientist.comOrder the Following Types of Electromagnetic Radiation: Microwaves, Gamma Rays, Green Light, Red Light, Ultraviolet Light, Continued • By wavelength (short to long). Gamma UV green red microwaves. • By frequency (low to high). Microwaves red green UV gamma. • By energy (least to most). Microwaves red green UV gamma. www.ThesisScientist.comLight’s Relationship to Matter • Single atoms can acquire extra energy/photons, and then they release it. • When atoms emit back energy, it usually is released in the form of light. • However, atoms don’t emit all colors, only very specific wavelengths.  In fact, the spectrum of wavelengths can be used to identify the element. www.ThesisScientist.comEmission Spectrum www.ThesisScientist.comSpectra www.ThesisScientist.comAbsorption spectrum Emission spectrum Absorption spectrum 656.3 486.1 434.1 410.2 Emission spectrum www.ThesisScientist.comThe Bohr Model of the Atom • The nuclear model of the atom does not explain how the atom can gain or lose energy. • Neils Bohr developed a model of the atom to explain how the structure of the atom changes when it undergoes energy transitions. • Bohr’s major idea was that the energy of the atom was quantized, and that the amount of energy in the atom was related to the electron’s position in the atom.  Quantized means that the atom could only have very specific amounts of energy. www.ThesisScientist.comThe Bohr Model of the Atom: Electron Orbits • In the Bohr model, electrons travel in orbits around the nucleus.  More like shells than planet orbits. • The farther the electron is from the nucleus the more energy it has. www.ThesisScientist.comThe Bohr Model of the Atom: Orbits and Energy, Continued • Each orbit has a specific amount of energy. • The energy of each orbit is characterized by an integer—the larger the integer, the more energy an electron in that orbit has and the farther it is from the nucleus. The integer, n, is called a quantum number. www.ThesisScientist.comThe Bohr Model of the Atom: Energy Transitions • When the atom gains energy, the electron leaps from a lower energy orbit to one that is further from the nucleus.  However, during that ―quantum leap‖ it doesn’t travel through the space between the orbits, it just disappears from the lower orbit and appears in the higher orbit. • When the electron leaps from a higher energy orbit to one that is closer to the nucleus, energy is emitted from the atom as a photon of light—a quantum of energy. www.ThesisScientist.comThe Bohr Model of the Atom www.ThesisScientist.comThe Bohr Model of the Atom: Ground and Excited States • In the Bohr model of hydrogen, the lowest amount of energy hydrogen’s one electron can have corresponds to being in the n = 1 orbit. We call this its ground state. • When the atom gains energy, the electron leaps to a higher energy orbit. We call this an excited state. • The atom is less stable in an excited state and so it will release the extra energy to return to the ground state.  Either all at once or in several steps. www.ThesisScientist.comThe Bohr Model of the Atom: Hydrogen Spectrum • Every hydrogen atom has identical orbits, so every hydrogen atom can undergo the same energy transitions. • However, since the distances between the orbits in an atom are not all the same, no two leaps in an atom will have the same energy.  The closer the orbits are in energy, the lower the energy of the photon emitted.  Lower energy photon = longer wavelength. • Therefore, we get an emission spectrum that has a lot of lines that are unique to hydrogen. www.ThesisScientist.comThe Bohr Model of the Atom: Hydrogen Spectrum, Continued www.ThesisScientist.comThe Bohr Model of the Atom: Success and Failure • The mathematics of the Bohr model very accurately predicts the spectrum of hydrogen. • However, its mathematics fails when applied to multielectron atoms. It cannot account for electronelectron interactions. • A better theory was needed. www.ThesisScientist.comThe QuantumMechanical Model of the Atom • Erwin Schrödinger applied the mathematics of probability and the ideas of quantizing energy to the physics equations that describe waves, resulting in an equation that predicts the probability of finding an electron with a particular amount of energy at a particular location in the atom. www.ThesisScientist.comThe QuantumMechanical Model: Orbitals • The result is a map of regions in the atom that have a particular probability for finding the electron. • An orbital is a region where we have a very high probability of finding the electron when it has a particular amount of energy. Generally set at 90 or 95. www.ThesisScientist.comOrbits vs. Orbitals Pathways vs. Probability www.ThesisScientist.comWave–Particle Duality • We’ve seen that light has the characteristics of waves and particles (photons) at the same time—how we view it depends on the application. • In the same way, electrons have the characteristics of both particles and waves at the same time. • This makes it impossible to predict the path of an electron in an atom. www.ThesisScientist.comThe QuantumMechanical Model: Quantum Numbers • In Schrödinger’s wave equation, there are 3 integers, called quantum numbers, that quantize the energy. • The principal quantum number, n, specifies the main energy level for the orbital. www.ThesisScientist.comThe QuantumMechanical Model: Quantum Numbers, Continued • Each principal energy shell has one or more subshells.  The number of subshells = the principal quantum number. • The quantum number that designates the subshell is often given a letter.  s, p, d, f. • Each kind of sublevel has orbitals with a particular shape.  The shape represents the probability map. 90 probability of finding electron in that region. www.ThesisScientist.comShells and Subshells www.ThesisScientist.comHow Does the 1s Subshell Differ from the 2s Subshell www.ThesisScientist.comProbability Maps and Orbital Shape: s Orbitals www.ThesisScientist.comProbability Maps and Orbital Shape: p Orbitals www.ThesisScientist.comProbability Maps and Orbital Shape: d Orbitals www.ThesisScientist.comSubshells and Orbitals • The subshells of a principal shell have slightly different energies.  The subshells in a shell of H all have the same energy, but for multielectron atoms the subshells have different energies.  s p d f. • Each subshell contains one or more orbitals.  s subshells have 1 orbital.  p subshells have 3 orbitals.  d subshells have 5 orbitals.  f subshells have 7 orbitals. www.ThesisScientist.comThe QuantumMechanical Model: Energy Transitions • As in the Bohr model, atoms gain or lose energy as the electron leaps between orbitals in different energy shells and subshells. • The ground state of the electron is the lowest energy orbital it can occupy. • Higher energy orbitals are excited states. www.ThesisScientist.comThe Bohr Model vs. the QuantumMechanical Model • Both the Bohr and quantummechanical models predict the spectrum of hydrogen very accurately. • Only the quantummechanical model predicts the spectra of multielectron atoms. www.ThesisScientist.comElectron Configurations • The distribution of electrons into the various energy shells and subshells in an atom in its ground state is called its electron configuration. • Each energy shell and subshell has a maximum number of electrons it can hold.  s = 2, p = 6, d = 10, f = 14.  Based on the number of orbitals in the subshell. • We place electrons in the energy shells and subshells in order of energy, from low energy up.  Aufbau principle. www.ThesisScientist.com6 7s 5f d 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p 3s 2p 2s www.ThesisScientist.com 1s EnergyFilling an Orbital with Electrons • Each orbital may have a maximum of 2 electrons. Pauli Exclusion principle. • Electrons spin on an axis. Generating their own magnetic field. • When two electrons are in the same orbital, they must have opposite spins. So their magnetic fields will cancel. www.ThesisScientist.comOrbital Diagrams • We often represent an orbital as a square and the electrons in that orbital as arrows.  The direction of the arrow represents the spin of the electron. Unoccupied Orbital with Orbital with orbital 1 electron 2 electrons www.ThesisScientist.comOrder of Subshell Filling in Ground State Electron Configurations Start by drawing a diagram 1s putting each energy shell on a row and listing the subshells 2s 2p (s, p, d, f) for that shell in 3s 3p 3d order of energy (left to right). 4s 4p 4d 4f Next, draw arrows through 5s 5p 5d 5f the diagonals, looping back to the next diagonal 6s 6p 6d each time. 7s www.ThesisScientist.comFilling the Orbitals in a Subshell with Electrons • Energy shells fill from lowest energy to highest. • Subshells fill from lowest energy to highest.  s → p → d → f • Orbitals that are in the same subshell have the same energy. • When filling orbitals that have the same energy, place one electron in each before completing pairs.  Hund’s rule. www.ThesisScientist.comElectron Configuration of Atoms in their Ground State • The electron configuration is a listing of the subshells in order of filling with the number of electrons in that subshell written as a superscript. 2 2 6 2 6 2 10 6 Kr = 36 electrons = 1s 2s 2p 3s 3p 4s 3d 4p • A shorthand way of writing an electron configuration is to use the symbol of the previous noble gas in to represent all the inner electrons, then just write the last set. 2 2 6 2 6 2 10 6 1 1 Rb = 37 electrons = 1s 2s 2p 3s 3p 4s 3d 4p 5s = Kr5s www.ThesisScientist.comElectron Configurations www.ThesisScientist.comExample—Write the Ground State Orbital Diagram and Electron Configuration of Magnesium. 1. Determine the atomic number of the element from the periodic table.  This gives the number of protons and electrons in the atom. Mg Z = 12, so Mg has 12 protons and 12 electrons. www.ThesisScientist.comExample—Write the Ground State Orbital Diagram and Electron Configuration of Magnesium, Continued. 2. Draw 9 boxes to represent the first 3 energy levels s and p orbitals. 1s 2s 2p 3s 3p www.ThesisScientist.comExample—Write the Ground State Orbital Diagram and Electron Configuration of Magnesium, Continued. 3. Add one electron to each box in a set, then pair the electrons before going to the next set until you use all the electrons. • When paired, put in opposite arrows.  1s 2s 2p 3s 3p www.ThesisScientist.comExample—Write the Ground State Orbital Diagram and Electron Configuration of Magnesium, Continued. 4. Use the diagram to write the electron configuration.  Write the number of electrons in each set as a superscript next to the name of the orbital set. 2 2 6 2 2 1s 2s 2p 3s = Ne3s  1s 2s 2p 3s 3p www.ThesisScientist.comExample—Write the Full Ground State Orbital Diagram and Electron Configuration of Manganese. − Mn Z = 25, therefore 25 e − s subshell holds 2 e 1s − p subshell holds 6 e  −  2 e 2s 2p − − d subshell holds 10 e +2 = 4e 1s 2s 2p 3s 3p 4s 3s 3p 3d − − +6 +2 = 12e f subshell holds 14 e 4s 4p 4d 4f − − +6 +2 = 20e +10 = 30e 3 d 2 2 6 2 6 2 5 Therefore the electron configuration is 1s 2s 2p 3s 3p 4s 3d Based on the order of subshell filling, we will need the first 7 subshells www.ThesisScientist.comPractice—Write the Full Ground State Orbital Diagram and Electron Configuration of Potassium. www.ThesisScientist.comPractice—Write the Full Ground State Orbital Diagram and Electron Configuration of Potassium, Continued. − K Z = 19, therefore 19 e − s subshell holds 2 e 1s − p subshell holds 6 e  −  2 e 2s 2p − − d subshell holds 10 e +2 = 4e 1s 2s 2p 3s 3p 4s 3s 3p 3d − − +6 +2 = 12e f subshell holds 14 e 2 2 6 2 6 1 Therefore the electron configuration is 4 1ss 2s 2 4p p 3s 3 4p d 4s 4f − +6 +2 = 20e Based on the order of subshell filling, we will need the first 6 subshells www.ThesisScientist.comExample—Write the Full Ground State Orbital 3+ Diagram and Electron Configuration of Sc . − Sc Z = 21, therefore 21 e 3+ − therefore Sc has 18 e − s subshell holds 2 e 1s − p subshell holds 6 e  −  2 e 2s 2p − − d subshell holds 10 e +2 = 4e 1s 2s 2p 3s 3p 4s 3s 3p 3d − − +6 +2 = 12e f subshell holds 14 e 4s 4p 4d 4f − +6 = 18e 2 2 6 2 6 Therefore the electron configuration is 1s 2s 2p 3s 3p Based on the order of subshell filling, we will need the first 5 subshells www.ThesisScientist.comPractice—Write the Full Ground State Orbital − Diagram and Electron Configuration of F . www.ThesisScientist.comPractice—Write the Full Ground State Orbital − Diagram and Electron Configuration of F , Continued. − F Z = 9, therefore 9 e − − therefore F has 10 e − s subshell holds 2 e 1s − p subshell holds 6 e −  2 e 2s 2p − − d subshell holds 10 e +2 = 4e 1s 2s 2p 3s 3p 4s 3s 3p 3d − − +6 +2 = 12e f subshell holds 14 e 4s 4p 4d 4f 2 2 6 Therefore the electron configuration is 1s 2s 2p Based on the order of subshell filling, we will need the first 3 subshells. www.ThesisScientist.comValence Electrons • The electrons in all the subshells with the highest principal energy shells are called the valence electrons. • Electrons in lower energy shells are called core electrons. • Chemists have observed that one of the most important factors in the way an atom behaves, both chemically and physically, is the number of valence electrons. www.ThesisScientist.comValence Electrons, Continued 2 2 6 2 6 2 10 6 1 Rb = 37 electrons = 1s 2s 2p 3s 3p 4s 3d 4p 5s • The highest principal energy shell of Rb that contains th electrons is the 5 , therefore, Rb has 1 valence electron and 36 core electrons. 2 2 6 2 6 2 10 6 Kr = 36 electrons = 1s 2s 2p 3s 3p 4s 3d 4p • The highest principal energy shell of Kr that contains th electrons is the 4 , therefore, Kr has 8 valence electrons and 28 core electrons. www.ThesisScientist.comPractice—Determine the Number and Types of Valence Electrons in an Arsenic, As, Atom. www.ThesisScientist.comPractice—Determine the Number and Types of Valence Electrons in an As Atom, Continued. − As Z = 33, therefore 33 e . 1s − 2 e 2s 2p − +2 = 4e 3s 3p 3d − +6 +2 = 12e 4s 4p 4d 4f − +6 + 2 = 20e − 5s +10 + 6 = 36e th The highest occupied principal energy level is the 4 . The valence electrons are 4s and 4p and there are 5 total. 2 2 6 2 6 2 10 3 Therefore, the electron configuration is 1s 2s 2p 3s 3p 4s 3d 4p . www.ThesisScientist.comElectron Configurations and the Periodic Table www.ThesisScientist.comElectron Configurations from the Periodic Table • Elements in the same period (row) have valence electrons in the same principal energy shell. • The number of valence electrons increases by one as you progress across the period. • Elements in the same group (column) have the same number of valence electrons and the valence electrons are in the same type of subshell. www.ThesisScientist.comElectron Configuration and the Periodic Table • Elements in the same column have similar chemical and physical properties because their valence shell electron configuration is the same. • The number of valence electrons for the main group elements is the same as the group number. www.ThesisScientist.comSubshells and the Periodic Table 1 s 2 1 2 3 4 5 2 s p p p p p s 1 6 p 2 1 2 3 4 5 6 7 8 9 10 d d d d d d d d d d 3 4 5 6 7 1 2 3 4 5 6 7 8 9 10 11 12 13 14 f f f f f f f f f f f f f f www.ThesisScientist.comElectron Configuration from the Periodic Table • The inner electron configuration is the same as the noble gas of the preceding period. • To get the outer electron configuration from the preceding noble gas, loop through the next period, marking the subshells as you go, until you reach the element.  The valence energy shell = the period number.  The d block is always one energy shell below the period number and the f is two energy shells below. www.ThesisScientist.comPeriodic Table and Valence Electrons • For the main group elements, the number of valence electrons is the same as the column number.  Except for He. • For the transition elements, the number of valence electrons is usually 2.  There are some elements whose electron configurations do not exactly fit our pattern.  Because as we traverse the transition metals we are putting electrons into a lower principal energy shell. www.ThesisScientist.comElectron Configuration from the Periodic Table 8A 1A 3A 4A 5A 6A 7A 2A 1 Ne 2 2 P 3s 3 3 3p 4 5 6 7 2 3 P = Ne3s 3p P has 5 valence electrons. www.ThesisScientist.comElectron Configuration from the Periodic Table, Continued 8A 1A 3A 4A 5A 6A 7A 2A 1 2 10 3d Ar 3 2 As 4 4s 3 4p 5 6 7 2 10 3 As = Ar4s 3d 4p As has 5 valence electrons. www.ThesisScientist.comPractice—Use the Periodic Table to Write the Short Electron Configuration and Orbital Diagram for Each of the Following and Determine the Number of Valence Electrons. • Na (at. no. 11). • Te (at. no. 52). www.ThesisScientist.comPractice—Use the Periodic Table to Write the Short Electron Configuration and Orbital Diagram for Each of the Following and Determine the Number of Valence Electrons, Continued. 1 • Na (at. no. 11). Ne3s 1 valence electron 3s 2 10 4 • Te (at. no. 52). Kr5s 4d 5p 6 valence electrons 5s 4d 5p www.ThesisScientist.comThe Explanatory Power of the QuantumMechanical Model • The properties of the elements are largely determined by the number of valence electrons they contain. • Since elements in the same column have the same number of valence electrons, they show similar properties. • Since the number of valence electrons increases across the period, the properties vary in a regular fashion. www.ThesisScientist.comThe Noble Gas Electron Configuration • The noble gases have 8 valence electrons.  Except for He, which has only 2 electrons. • We know the noble gases are especially non reactive.  He and Ne are practically inert. • The reason the noble gases are so non reactive is that the electron configuration of the noble gases is especially stable. www.ThesisScientist.comEveryone Wants to Be Like a Noble Gas The Alkali Metals • The alkali metals have one more electron than the previous noble gas. • In their reactions, the alkali metals tend to lose their extra electron, resulting in the same electron configuration as a noble gas. Forming a cation with a 1+ charge. www.ThesisScientist.comEveryone Wants to Be Like a Noble Gas The Halogens • The electron configurations of the halogens all have one fewer electron than the next noble gas. • In their reactions with metals, the halogens tend to gain an electron and attain the electron configuration of the next noble gas.  Forming an anion with charge 1−. • In their reactions with nonmetals, they tend to share electrons with the other nonmetal so that each attains the electron configuration of a noble gas. www.ThesisScientist.com 80Everyone Wants to Be Like a Noble Gas • As a group, the alkali metals are the most reactive metals. They react with many things and do so rapidly. • The halogens are the most reactive group of nonmetals. • One reason for their high reactivity is the fact that they are only one electron away from having a very stable electron configuration. The same as a noble gas. www.ThesisScientist.comStable Electron Configuration and Ion Charge • Metals form cations by losing valence Atom Atom’s Ion Ion’s electrons to get the electron electron same electron config config 1 + configuration as the Na Ne3s Na Ne previous noble gas. 2 2+ Mg Ne3s Mg Ne • Nonmetals form 2 1 3+ Al Ne3s 3p Al Ne anions by gaining 4 2 O He2s2p O Ne valence electrons to 2 5 F He2s 2p F Ne get the same electron configuration as the next noble gas. www.ThesisScientist.comPeriodic Trends in the Properties of the Elements Trends in Atomic Size • Either volume or radius.  Treat atom as a hard marble. • As you traverse down a column on the periodic table, the size of the atom increases.  Valence shell farther from nucleus.  Effective nuclear charge fairly close. • As you traverse left to right across a period, the size of the atom decreases.  Adding electrons to same valence shell.  Effective nuclear charge increases.  Valence shell held closer. www.ThesisScientist.comTrends in Atomic Size, Continued www.ThesisScientist.comGroup IIA 2e 2e + Be (4p and 4e ) + 4 p 2e 8e + Mg (12p and 12e ) 2e + 12 p 2e 8e 8e + Ca (20p and 20e ) 2e + 16 p www.ThesisScientist.comPeriod 2 1e 2e 3e 2e 2e 2e + + + 3 p 4 p 5 p + + + Li (3p and 3e ) Be (4p and 4e ) B (5p and 5e ) 4e 6e 8e 2e 2e 2e + + + 6 p 8 p 10 p + + + C (6p and 6e ) O (8p and 8e ) Ne (10p and 10e ) www.ThesisScientist.comCovalent Radius, elements 1 58 250 200 150 100 50 0 Atomic Number www.ThesisScientist.com 1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 Radius, pmExample 9.6 – Choose the Larger Atom in Each Pair • C or O • Li or K • C or Al • Se or I www.ThesisScientist.comPractice—Choose the Larger Atom in Each Pair. 1. N or F 2. C or Ge 3. N or Al 4. Al or Ge www.ThesisScientist.comPractice—Choose the Larger Atom in Each Pair, Continued. 1. 1. 1. 1. N N N N o o o or r r r F F F F, N is further left 2. 2. 2. C C C o o or r r Ge Ge, Ge Ge is further down 3. 3. N N o or r Al Al, Al is further down left 4. Al or Ge opposing trends www.ThesisScientist.comIonization Energy • Minimum energy needed to remove an electron from an atom. Gas state. Endothermic process. Valence electron easiest to remove. 1+ M(g) + 1st IE  M (g) + 1 e +1 2+ M (g) + 2nd IE  M (g) + 1 e First ionization energy = energy to remove electron from neutral atom; 2nd IE = energy to remove from +1 ion; etc. www.ThesisScientist.comIonization Energy of Elements 156 2500 2000 1500 1000 500 0 Elements by Atomic Number www.ThesisScientist.com H Be N Ne Al S K Ti Mn Zn As Kr Y Mo Rh Cd Sb Xe Ionization Energy, kJ/molIonization Energy of Group IA 1400 H 1200 1000 800 600 Li Na K 400 Rb Cs 200 0 H Li Na K Rb Cs Elements by Period Number www.ThesisScientist.com Ionization Energy, kJ/molCovalent Radii of Group IA 250 6 Cesium 5 Rubidium 4 Potassium 200 3 Sodium 150 2 Lithium 100 50 1 Hydrogen 0 Hydrogen Lithium Sodium Potassium Rubidium Cesium 1 2 3 4 5 6 Group Number Ionization Energy, Group IA 1400 H 1200 1000 800 600 Li Na K 400 Rb Cs 200 www.ThesisScientist.com 0 H Li Na K Rb Cs Group Number Radii, pm Energy, kJ/molIonization Energy of Periods 2 3 2500 Ne 2000 F Ar 1500 N O Cl C P 1000 S Be B Si Mg Al 500 Li Na 0 Li Be B C N O F Ne Na Mg Al Si P S Cl Ar Elements by Group Number www.ThesisScientist.com Ionization Energy, kJ/molTrends in Ionization Energy • As atomic radius increases, the ionization energy (IE) generally decreases.  Because the electron is closer to the nucleus. • 1st IE 2nd IE 3rd IE … • As you traverse down a column, the IE gets smaller.  Valence electron farther from nucleus. • As you traverse left to right across a period, the IE gets larger.  Effective nuclear charge increases. www.ThesisScientist.comTrends in Ionization Energy, Continued www.ThesisScientist.comExample—Choose the Atom in Each Pair with the Higher First Ionization Energy 1. 1. 1. 1. Al Al Al Al o o o or r r r S S S S, Al is further left 2. 2. 2. As As As o o or r r Sb Sb Sb, Sb is further down 3. 3. N N o or r Si Si, Si is further down and left 4. O or Cl, opposing trends www.ThesisScientist.comPractice—Choose the Atom with the Highest Ionization Energy in Each Pair 1. Mg or P 2. Cl or Br 3. Se or Sb 4. P or Se www.ThesisScientist.comPractice—Choose the Atom with the Highest Ionization Energy in Each Pair, Continued 1. Mg or P 2. Cl or Br 3. Se or Sb 4. P or Se www.ThesisScientist.comMetallic Character • How well an element’s properties match the general properties of a metal. • Metals:  Malleable and ductile as solids.  Solids are shiny, lustrous, and reflect light.  Solids conduct heat and electricity.  Most oxides basic and ionic.  Form cations in solution.  Lose electrons in reactions—oxidized. • Nonmetals:  Brittle in solid state.  Solid surface is dull, nonreflective.  Solids are electrical and thermal insulators.  Most oxides are acidic and molecular.  Form anions and polyatomic anions.  Gain electrons in reactions—reduced. www.ThesisScientist.comMetallic Character, Continued • In general, metals are found on the left of the periodic table and nonmetals on the right. • As you traverse left to right across the period, the elements become less metallic. • As you traverse down a column, the elements become more metallic. www.ThesisScientist.comTrends in Metallic Character www.ThesisScientist.comExample—Choose the More Metallic Element in Each Pair 1. 1. 1. 1. Sn Sn Sn Sn o o o or r r r T T T Te e e e, Sn is further left 2. 2. 2. P P P o o or r r Sb Sb Sb, Sb is further down 3. 3. Ge Ge o or r In In, In is further down left 4. S or Br opposing trends www.ThesisScientist.comPractice—Choose the More Metallic Element in Each Pair 1. Sn or Te 2. Si or Sn 3. Br or Te 4. Se or I www.ThesisScientist.comPractice—Choose the More Metallic Element in Each Pair, Continued 1. Sn or Te 2. Si or Sn 3. Br or Te 4. Se or I www.ThesisScientist.com
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