Bonding in solids: the general idea

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● Bonds between atoms: contents
● Bonding in solids: the general idea
● Repulsive force
● Ionic bonding
● Turning Atoms in Ions
● Ionic bonding
● Repulsive force
● Covalent bonding
● The covalent bond: simple picture
● The covalent bond: a closer look at C
● Bonding in most semiconductors
● The covalent bond: sp2 bonding
● Covalent bonding
● Metallic bonding
● metals / non-metals
● Metallic bonding (simple metals)
● Metallic bonding: why is this so favorable?
● Transition metals
● Bonds between molecules
● Bonds between molecules: hydrogen bonds
● Bonds between molecules: van der Waals force
● Bond type and physical properties
● Summary

نوع زبان: انگلیسی حجم: 2.33 مگا بایت
نوع فایل: اسلاید پاورپوینت تعداد اسلایدها: 36 صفحه
سطح مطلب: نامشخص پسوند فایل: ppt
گروه موضوعی: زمان استخراج مطلب: 2019/05/17 02:35:35

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عبارات مهم استفاده شده در این مطلب

عبارات مهم استفاده شده در این مطلب

energy, ., bonding, solid, electron, ev, atom, ion, cohesive, cl, force, gain,

توجه: این مطلب در تاریخ 2019/05/17 02:35:35 به صورت خودکار از فضای وب آشکار توسط موتور جستجوی پاورپوینت جمع آوری شده است و در صورت اعلام عدم رضایت تهیه کننده ی آن، طبق قوانین سایت از روی وب گاه حذف خواهد شد. این مطلب از وب سایت زیر استخراج شده است و مسئولیت انتشار آن با منبع اصلی است.

http://philiphofmann.net/book_material/lectures/lecture2_gen.ppt

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عبارات پرتکرار و مهم در این اسلاید عبارتند از: energy, ., bonding, solid, electron, ev, atom, ion, cohesive, cl, force, gain,

مشاهده محتوای متنیِ این اسلاید ppt

مشاهده محتوای متنیِ این اسلاید ppt

lectures accompanying the book solid state physics an introduction by philip hofmann ۲nd edition ۲ ۱۵ isbn ۱ ۳۵۲۷۴۱۲۸۲۴ isbn ۱۳ ۹۷۸ ۳۵۲۷۴۱۲۸۲۲ wiley vch berlin. www.philiphofmann.net bonds between atoms contents bonding in general attractive and repulsive forces cohesive energy ionic bonding covalent bonding metallic bonding hydrogen bonding and van der waals bonding relationship between bonding type and some physical properties of a solid in particular melting point at the end of this lecture you should understand …. overview over each lecture key headings there must be two sorts of forces no attractive no solid no repulsive total collapse and no solid either attractive forces long range we shall see repulsive at short range bonding in solids the general idea valence electrons of the outer shell achieve bonding like in chemistry decrease in total energy stabilises the solid the solid’s energy is lower than that of sum of atoms it is made of so the energy gain by the bonding must be higher than the energy it costs to promote electrons from the atomic orbitals to the electronic states of the solid. this energy difference is a measure for the strength of the bond. it is called the cohesive energy. cohesive energy energy of atoms energy of solid the latter is certainly the case for ionic bonding which we discuss now in any case two type of forces one to hold the atoms together one to keep them from crashing into each other. repulsive force m would usually be ۱ of course n would be at least ۶ why so hard to get them closer and why does it happen at these distances pauli principle all states already occupied. we can push more in but if we want to do this we have to push all states to higher energies it is not the coulomb repulsion between the nuclei this is essentially the same for all atoms but now we look at the attractive part. ionic bonding form positive and negative ions here na and cl bonding is achieved by electrostatic force and a classical treatment is partially meaningful. example nacl rock salt cubic structure first type we discuss simple and we can use simple tools to give a reasonable prediction of the energy balance typical na only one ۱ electron which is cheap to remove cl has ۷ valence electrons ۲s and ۵p and needs one more to achieve the special closed shell configuration. discuss structure. knowing the structure we can actually calculate the relevant energies. how we know the structure is a different matter … turning atoms in ions how much energy does it cost example nacl ionization energy na ۵.۱ ev electron affinity cl ۳.۶ ev net energy cost ۵.۱ ev ۳.۶ ev ۱.۵ ev per pair energy balance we have na and cl atoms and want to produce ions ionization energy is energy it takes to remove one electron. we know this already for na electron affinity is the energy gain when we add an extra electron to the neutral atom. positive means actual gain. this is ۳.۶ ev for cl so the net cost is the difference ionic bonding what is the energy gain example nacl so the total gain is ۵.۱ ev ۱.۵ ev ۳.۶ ev ۲.۸ å we want to do all classical but we are cheating a little because a ۲.۸ aa falls out of the sky so this is the total energy for one molecule. it must be higher for a solid …. ionic bonding but this was just a molecule what about the electrostatic energy gain in the solid example nacl consider the centre na ion energy gain from next ۶ cl alternating negative and positive terms in a series. factor for the series is the normal coulomb attraction for a pair ionic bonding example nacl eventually the series converges and we get for one ion md is called the madelung constant. it is specific for a given structure. it is good that this is higher that ۱ because otherwise salt would come in molecules not in crystals point out the difference between lattice and cohesive energy cohesive energy is total energy for forming solid from atoms it is also the more relevant thing to look at. ionic bonding so the total lattice energy for one mole of nacl to count every pair only once because there are na and cl ions this gives ۸۶۱ kjmol ۱. the experiment gives ۷۷۶ kjmol ۱ note this is the lattice energy not the cohesive energy the lattice energy minus the energy to turn atoms into ions . total energy we considered only ۱ na ion but we also need the cl ion same energy we calculate the binding with every other atom but in this way we count every bond twice. so divide again by two in the end it’s just avogadro’s number times e a few ev exercise but there is a big problem in all this we have been cheating a bit because we can gain ever more energy by making a smaller note the energies given are actually the lattice energies. how to measure dissolve repulsive force the existence of a non classical repulsive force causes the real cohesive energy to be slightly smaller ۱ than the value calculated by the coulomb potential. ۱ our cheating has another consequence in agreement with the experiment bottom line also seen in exercise cohesive energy a few ev. covalent bonding a detailed view on the hydrogen molecule identical particles later in connection with magnetism see online note on www.philiphofmann.net . a simple view on other covalent bonds. more complex bonding true electron sharing and highly directional the covalent bond simple picture the covalent bond less simple picture hydrogen molecule see note on www.philiphofmann.net so simple that you might be intellectually offended …. number of additional or missing valence electrons as arms more complex bonding true electron sharing and highly directional the covalent bond simple picture number of additional or missing valence electrons as …

کلمات کلیدی پرکاربرد در این اسلاید پاورپوینت: energy, ., bonding, solid, electron, ev, atom, ion, cohesive, cl, force, gain,

این فایل پاورپوینت شامل 36 اسلاید و به زبان انگلیسی و حجم آن 2.33 مگا بایت است. نوع قالب فایل ppt بوده که با این لینک قابل دانلود است. این مطلب برگرفته از سایت زیر است و مسئولیت انتشار آن با منبع اصلی می باشد که در تاریخ 2019/05/17 02:35:35 استخراج شده است.

http://philiphofmann.net/book_material/lectures/lecture2_gen.ppt

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