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Energy and Periodic Trends Unit: Energy and Periodic Trends Topic: Periodic Table Trends Objectives: Day 1of 2 • To understand the types of radiation • To learn about ionization energy and how it relates to the periodic table • To learn about electronegativity and how it relates to the periodic table Quickwrite Answer one of the questions below 1-2 sentences: • If you recall, which group of the periodic table readily gives up electrons to form cations?? • If you recall, which group of the periodic table readily gains electrons to form anions?? Atomic Properties • Science is based on observations and discoveries • For example, certain observations about substances will help us better understand our world • We know that wood burns, steel rusts, plants grow, and sugar tastes sweet • A better understanding of how atoms and molecules behave is crucial to helping us explore our natural world • The periodic table is an important tool in helping us understand why atoms have predictable characteristic properties • The objective is to understand the general trends or patterns in atomic properties in the periodic table Metals, Semimetals, & Nonmetals • If you recall, the periodic table is divided into 3 basic different types of elements: -Metals -Semimetals -Nonmetals Metals Semi Metals Nonmetals Atomic Properties & the Periodic Table 1+ Cations 2+ Cations 3+ Cations 2- Anions 1- Anions If you recall, group 1 metals like to lose an electron and group 2 metals like to lose an two electrons, becoming positively charged Non metals on the other hand, like to gain electrons and become negatively charged Atomic Properties & the Periodic Table Lithium is the least likely to lose an electron Cesium loses an electron most easily But what elements in group 1 are the most likely to lose an electron? Not all metals in group 1 behave exactly the same way For example, some metals can lose one or more electrons much more easily than others Cesium at the bottom of group 1, gives up an electron much more easily than lithium at the top of group 1 Atomic Properties & the Periodic Table In fact, as we go down the periodic table, the metals in group 1 become more likely to lose an electron Cs > Rb > K > Na > Li Cesium loses an electron most easily Lithium is the least likely to lose an electron Group 1 Atomic Radius (Size) Period 4 What do you notice about relative What do you the notice aboutsizes the of the atoms as we move up group as 1? we mov relative sizes of period 4 atoms That’s right the atomic radius gets across the periodic table leftsmaller! to right? That’s right the atomic radius gets small Atomic Radius (Size) Atomic Size Decreases Atomic Size Decreases Atomic Size Li Na K Atomic Size Decreases Rb • What makes the atomic size get bigger? • Their nucleus and electron cloud size becomes larger Atomic Size Decreases Cs Na Mg Al Si P S Cl Ar How does atomic Size Change across the Periodic table? decreases as we go • Atomic size ________ Decreases up the periodic table and decreases as we go left to right • Their nucleus and electron cloud larger gets ________ Decreases • Draw: Answer Bank Weakly larger Attract remove Decreases low Ionization Energies • The ionization energy is the energy required to remove an electron from an individual atom • Think of it as how easily an atom loses an electron • Metals have low ionization energies, and nonmetals tend to have higher ionization energies Sodium (Na) Atom e- How much energy is required to remove an electron from a sodium atom? 1+ e- e- e- e- Recall that sodium likes to lose an electron to form a +1 ion P+ NNP+P+ NP+ P+ N P+P+ P+ N eN NP+ P+ P+NP+ e- In general, metals such as sodium have low ionization energies? e- e-- e- Na + energy Na+1 + e ee- e- Ionization Energy Ionization Energy Increases Ionization Energy Increases What do you aboutEnergy the relative Notice thenotice Ionization trend sizes of the atoms as we move up from cesium to Lithium? What is Ionization Energy? • The energy required to ______ remove an electron from an individual atom • Metals (group 1 & 2) have _____ low ionization energies and nonmetals (group 17 halogens & group 18 noble gases) have high ionization energies Increases • Draw: Answer Bank Weakly larger Attract remove Decreases low Increases Electronegativity • If Ionization energy is how easily an atom loses an electron, then think of electronegativity as the exact opposite • Electronegativity is the ability of an atom to attract electrons • Think of it as the liking or attraction an atom has for an electron • Nonmetals such as Flourine, chlorine and oxygen have high electronegativities • In other words, Flourine, Chlorine and Oxygen love to steal electrons form other atoms Electronegativity Electronegativity Increases Electronegativity increases What do you about the relative Notice thenotice Electronegativity trend sizes of the atoms as we move up from cesium to Lithium? What is Electronegativity? The ability of an atom to _______electrons attract • • Think of it as the attraction an atom has for Answer Bank an electron Weakly larger • Nonmetals such as Fluorine, Chlorine and Attract Oxygen have high electronegativities along remove with noble gases such as Helium and argon Increases • Draw: Decreases low Increases Electronegativity vs. Ionization Energy • What determines Ionization energy and Electronegativity? The answer is atomic radius! P+ NNP+P+ NP+ P+P+NP+ P+ NN NP+ P+P+ NP+ e- atoms lose Larger Electrons easier because the outer electrons are farther from the nucleus, & are therefore more weakly held Electronegativity vs. Ionization Energy • What determines Ionization energy and Electronegativity? The answer is atomic size! P+ NNP+P+ NP+P+ e- P+ P+ N P+ NN NP+ P+P+ NP+ Smaller atoms like fluorine hold their outer electrons are closer to the Nucleus and therefore e- do not Lose their electrons as easy This also enables them to steal Electrons from other atoms (High electronegativity) The more Electronegative Atom, Fluorine in this case, steals the weakly held outer electrons from Cesium NNP+P+ NP+ P+P+e- P+ N P+ P+ N N P+ NP+ P+ P+N e- P+ NNP+P+ NP+ N P+P+ P+ P+ N N P+ NP+ P+ P+N Fluorine Cesium e- How does atomic size effect ionization energy and electronegativity? • Larger atoms (cesium) with low ionization energies weakly ______ hold their outer electrons and therefore easily lose them • Smaller atoms (fluorine) with high electronegativities strongly hold their electrons closer to the nucleus and therefore steal electrons from other atoms Answer Bank Weakly larger Attract remove Decreases low Summarize: • List 3 atoms with a large atomic radius: • Explain where atoms with low ionization energies can be found: List 3 examples: • Explain where the most electronegative atoms can be found: List 3 examples: • Explain where the largest atomic size can be found on the periodic table: Unit: Light & Periodic Trends Topic: Energy and Light Objectives: Day 2 of 2 • To understand different properties of light such as wavelength and frequency • To understand how light is given off on the atomic level Quickwrite Answer one of the questions below 1-2 sentences: • How do you think atoms give off light???? • What is radiation??? What are some different forms of radiation you might have heard of???? Energy and Light • If you hold your hand a few inches from a brightly glowing light bulb what do you feel? • Your hand gets warm! • The light from bulb somehow transmits energy to your hand • The same thing happens when you move close to the glowing embers of wood in a fire place • The energy you feel from the sun is a similar example Energy and Light • In all 3 of these examples, energy is being transmitted from one place to another by light—more properly called electromagnetic radiation • Many kind of electromagnetic radiation exist, including x-rays, used to penetrate your skin and produce images of your bones, microwaves to cook your food, and radio waves so you can call a friend on your cell phone What is electromagnetic radiation? • Energy transfer in the form of_______ waves • Examples include: light, x-rays, radio waves, infrared (heat) waves Answer Bank Between Time excited packet Waves ground Energy and Light • How do these various types of electromagnetic radiation differ from one another? To answer this question we need to talk about waves • Waves are characterized by 3 properties: wavelength, frequency and speed. • The wavelength symbolized by the symbol lamda (λ) • It is the distance between 2 consecutive wave peaks Energy and Light • How do these various types of electromagnetic radiation differ from one another? To answer this question we need to talk about waves • Waves are characterized by 3 properties: wavelength, frequency and speed. • The wavelength symbolized by the symbol lamda (λ) • It is the distance between 2 consecutive wave peaks λ What is wavelength? • The distance ________ between 2 consecutive wave peaks Answer Bank Between Time excited packet Waves ground Energy and Light • The frequency of a wave (symbolized by the greek letter nu, ν) indicates how many times a peak passes by a point for a given time period • Think of it as how many times the blue circle goes up and down every minute What is the frequency? • The frequency of a wave (symbolized by the greek letter nu, ν) indicates how many times a peak passes by a point for a given _____ time period • (Think of it as how many times the blue circle goes up and down every minute) Answer Bank Between Time excited packet Waves ground Energy and Light • Light waves, x-rays, radio waves are all classified based on their wavelength • Notice that x-rays have very short wavelengths, where as microwaves and radio waves have very long wavelengths Radiation Link • http://www.classzone.com/books/earth_sci ence/terc/content/visualizations/es2601/es 2601page01.cfm?chapter_no=visualizatio n Energy and Light • The interesting thing about electromagnetic radiation is that it doesn’t always behave like as though it were a wave • Sometimes electromagnetic radiation can have properties that are characteristic of particles Energy and Light • Another way to think of a beam light traveling through space is as a stream of tiny packets of energy called photons What is photon? Packet • A “particle or _______ of energy” of electro magnetic radiation Answer Bank Between Time excited packet Waves ground Energy and Light So what is the exact nature of radiation and light? • Is it a particle or wave? It seems both • This situation is often referred to as the wave-particle nature of light Energy and Light • Different wavelengths of electromagnetic radiation carry different amounts of energy • Shorter wavelengths carry less energy than longer wavelengths Is it a particle or wave? It seems both Energy levels of Helium • An atom that it is excited can release energy in the form of light or photons • An atom that is not excited is said to be in it’s ground state rather than it’s excited state eHelium Atom e- Excited State Ground State (high energy level) (low energy level) P+ N N P+ e- e- How does an atom give off light? • An atom absorbs energy and becomes “_________” excited • The electrons are now in an excited state (higher energy level) • As electron return to their ______ ground state (low energy level), they give off light or photons • The type of light (red or blue light) being emitted is dependent upon the difference in energy between the ground and excited states Answer Bank Between Time excited packet Waves ground Summarize: • List 3 different types of radiation: • What’s the difference between wavelength and frequency: • How is a photon different from a wave? • In your own words, explain how light is given off on the atomic level: Can I Remove More Than One Electron? • A second, third, etc, electron can be removed from an atom. • The ionization energies are termed accordingly: – 2nd Ionization energy to remove the 2nd electron. – 3rd Ionization energy to remove the 3rd electron. ns2np6 ns2np5 ns2np4 ns2np3 ns2np2 ns2np1 d10 d5 d1 ns2 ns1 Ground State Electron Configurations of the Elements 4f 5f 8.2