学习日记（foundation-chemistry）
chapter5：Atomic Structure and the Periodic Table
- Different Theories of the Atom
- Classical 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：所有东西都有重量和体积
-Energy：不可分解的分子，但可以通过waves里面流动
- The Nature of Light—Its Wave Nature
-Electromagnetic radiation 是通过waves产生的; traveling at a velocity “c”
-Electromagnetic radiation 通过waves来移动然后通过pond的surface
-wave有4个点，来确认他们的特点
。wave speed,
。height (amplitude),
。length,
。number of wave peaks that pass in a given time.
-所有的electromagnetic waves会移动穿过空间在同样的，固定的速度
。3.00 x 10^8 meters per second in a vacuum = speedof light, c.
- Characterizing Waves
-amplitude=wave的高度
。是从node到crest的距离
。是来测量intense of the light -amplitude越大，light越亮
-wavelength(λ)=测量wave cover的距离
。是2个crest之间的距离
。是个完整的cycle2π
。通常用nanometers来测量，1 nm = 1 x 10-9 m
-frequency(ν)=waves通过一段时间（period）的数量
。The number of waves = number of cycles.
。Units are hertz (Hz), or cycles/s = s-1.1 Hz = 1 s-1
-The speed of light: c = νλ
。Radiation with a high frequency has a short wavelength, and vice versa
- The Electromagnetic Spectrum
-continuous spectrum=光通过prism分散出来的所有颜色
- Color
。或者frequency
-白光是所有visible light的混色
。spectrum
。Red，Orange，Yellow，Green，Blue，Violet.
-当一个东西absorbs一些白光的wavelength，通过reflecting，就会出现颜色
。observed colour是主要被reflected的颜色
。被叫transmitted light
- Types of Electromagnetic Radiation
。Radiowaves = λ > 0.01 m.
*Low frequency and energy.
。Microwaves = 10-4m < λ < 10-2 m.
。Infrared (IR) = 8 x 10-7 < λ < 10-5 m.
。Visible = 4 x 10-7 < λ < 8 x 10-7 m.
*ROYGBIV.
。Ultraviolet (UV) = 10-8 < λ < 4 x 10-7 m.
。X-rays = 10-10 < λ < 10-8 m.
。Gamma rays = λ < 10-10.
*High frequency and energy.
- Particles of Light
particles call photons.
-简单讲被electromagnetic radiation分解出来的particles叫photon
-也叫做光能量的分子
-Blackbody Radiation
。当固体被加热到1000K，它会emit visible light（red glow）
-当1500K，光会越来越亮，越来越橙
-当超过2000K，光会越来越亮，越来越白
-Changes in intensity and wavelength of emitted light as an object is heated
- Quantization of Energy
-radiation是emitted by atoms which is contained within it
-如果atom可以emit certain quantities of energy，就代表atom本身就有quantities of energy
-当atom的energy被quantized：it exists 在certain固定的quantities rather than 它继续
-可以理解喂，atom quantized的时候会跳来跳去到不同的quantities直到它stable，他就会fixed了
-当然跳来跳去的时候也会出现gain或者loss energy
-每次gain 或者loss energy会称为quantum，此时energy可通过formulaE=hv来计算
- Particles of Light
。Flow of current (emission of electrons) 当monochromatic light of sufficient frequency 在 a clean metallic surface闪烁会出现
。光在metal上面闪的时候会有minimum frequency或者是没有current flows，不同的铁会有不同的frequency
。Absence of time lag-Current flows the moment light of this minimum frequency shines on the metal
- Photon Theory of Light
-简单讲就是atom会变化成能力然后可以absorbs或者emits one photon of light，因为它们会“跳来跳去”
- The Electromagnetic Spectrum andPhoton Energy
-Short wavelength light have photons with highest energy = high frequency
-High-energy electromagnetic radiation can potentially damage biological molecules.
- Atomic Spectra
-当atoms emit back energy，通常会释放光
-当然atoms不会emit所有的颜色
。通过spectrum of wavelength可以分辨出element
-当光背hydrogen atom刺激会通过narrow slit然后被prism refracted
。它不会呈现continuous spectrum，但是会呈现line spectrum
。The wavelengths of these spectral lines are characteristic of the element producing them
-Rydberg equation
λ = wavelength of a spectral line
n1 and n2 = positive integers with n2 > n1
R = Rydberg constant (1.096776 x 107 m-1)
- The Bohr Model of the Atom
-Neils Bohr就开发一个model给H atom然后predicted the existence of line spectra.
-他的想法是atom的energy会被quatized，然后那些在atom里面的energy跟electron在一个atom的位置是有关联的
- The Bohr Model of the Atom:Electron Orbits
-在Bohr model,electron会travel在fixed circular obits在nucleus附近
-离nucleus越远的electron越多energy
- The Bohr Model of the Atom:Orbits and Energy
-每个orbit 有特定的energy
-每个orbit的energy被integer化，越大的integer，越多energry，离nucleus越远
。integer，n=quantum number.
- The Bohr Model of the Atom:Energy Transitions
-当atom gain energy，electron会从lower energy orbit leaps去其中一个离nucleus较远的那个orbit
。当“quantum leap”的时候它不是直接穿过，而是在lower orbit 消失然后再较高的orbit出现
- The Bohr Model of the Atom:Ground and Excited States
-在 Bohr model of hydrogen,最低的amount of energy hydrogen's one electron 会corresponds 去n=1 orbit，那个我们叫ground state
-当atom gains energy，electron leap去higher energy orbit，那个叫exicited state
-atom 不stable 是在 excited state ，会释放额外的energy让atom回到ground state
。会通过一个step，或者很多个steps
- The Bohr Model of the Atom: Postulates
-electron 在特定的orbit会有特定的energy但不会radiate energy
-atom 会通过absorb或者emit photon产生的差别而变化，Ephoton = Efinal – Einitial = hυ
- The Wave of Electrons and ParticleNature of Photons
-如果electrons是wave的样子的，就会有固定的radii，所以是由可能有特定的frequencies和energies的
- The Heisenberg Uncertainty Principle
-如果electron 有paticle和wave特性，我们就可以知道它是什么atom
-但是我们不可能完全准确的知道它们的位置因为每个momentum of a particle是simultaneously的
- The Quantum-Mechanical Model of the Atom
-orbital=是一个用probability来找electron的方法，当它有特定的amount of energry
- The Quantum-Mechanical Model:Quantum Numbers
quantum numbers, that quantize the energy.
。Principles quantum number (n)
*specifies the main energy level for the orbital.
*Indicates the relative size of the orbital
*n is a positive interger (1,2,3,4 …)
*Each principal energy shell has one or more subshells.The number of subshells = the principal quantum number.
。Angular Momentum quantum number (l)
*An integer from 0 to n – 1 for each value of n
*The value of l for a particular orbital is designated by the letters s, p, d, f corresponding to l values of 0,1, 2, and 3 respectively
*The shape represents the probability map.90% probability of finding electron in that region.
。Magnetic quantum number (ml)
*The number of possible ml values equals the number of orbitals, which is 2l + 1 for a given l value
*The number of subshells = the principal quantum number.
*An integer from –l to + l including zero
- Subshells and Orbitals
。The subshells in a shell of H atom全部有相同的 energy,但是multielectron atoms the subshells 有不同的 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.
- The Bohr Model vs.the Quantum-Mechanical Model
-只有quantum-mechanical models可以分辨spectra of multi-electron atoms.
- Quantum Numbers
value
-Sublevel.The atom’s level contain sublevels, or subshells,
which designate the orbital shape.
l = 0 is an s sublevel
l = 1 is a p sublevel
l = 2 is a d sublevel
Sublevel被命名来代表n value和它的letter designate.
-Orbital. 它们被允许combination of n, l, ml values 在特定的 atom’s orbitals. 所以, 那些three quantum numbers 是来描述orbital express its size (energy), shape, and spatial orientation.
- Electron Configurations
-每个 energy shell 和subshell 有限制可以hold的number of electrons
。s = 2, p = 6, d = 10, f = 14.
。Based on the number of orbitals in the subshell.
-我们放 electrons 进energy shells 和 subshells会根据它们的energy , 从低到高
。Aufbau principle.
- Filling an Orbital with Electrons
。产生它们自己的磁场
-当2个 electrons在相同的orbital ，它们会有opposite spins.
。它们的磁场就会取消
-Electron spin quantum number, ms
。只可能是2个values + ½ or – ½
-每个orbital 最多只可以有有2个electrons
。Pauli Exclusion principle.
。没有2个electrons 在 an atom 会有同样 set of quantum numbers
- Orbital Diagrams
-通常orbital会用正方形来代表，而electron会用箭头来代表.
。箭头的方向呈现了electron的 spin
- Order of Subshell Filling in Ground State Electron Configurations
接下来就是先排往上的的箭头，才排往下的箭头
- Filling the Orbitals in a Subshell with Electrons
-Subshells 从 lowest energy到highest来填.
。s → p → d → f
。1s2s2p3s3p4s3d4p5s4d5p6s5d5p
-Orbitals 在相同的subshell会有相同的energy (degenerate orbitals).
。Hund’s rule.
- Valence Electrons
-Electrons 在lower energy shells 叫 core electrons.
-可以通过这些来观察an atom 行为
- Modern Periodic Table
- Electron Configurations and the Periodic Table
-Elements 在same period (row) 有 valence electrons 在 same principal energy shell.
-number of valence electrons 会一个一个增加，在across the period.
-Elements 在 same group (column) 会有同样多的valence electrons在同一个subshell
-Elements 在同样column 会有类似的chemical and physical properties因为它们的 because their valence shell electron configuration 是一样的
-The number of valence electrons for the main group elements = the group number.
-The inner electron configuration = 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.
- Periodic Table and Valence Electrons
-For main group elements, the valence electrons是outer electrons.
number of valence electrons=the column number.
。Except for He.
-transition elements, the (n-1)d electrons 可以被计算通过 valence electrons 因为有些或者全部会涉及到bonding
- The Explanatory Power of the Quantum-Mechanical Model
-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.
- The Noble Gas Electron Configuration
。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.
- Everyone Wants to Be Like a Noble Gas!
。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.
-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.
-others
。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.
- Stable Electron Configuration and Ion Charge
same electron configuration as the previous noble gas.
-Nonmetals form anions by gaining valence electrons to get the same electron configuration as the next noble gas.
- Periodic Trends in the Properties of the Elements：Sizes of Atoms
- Trends in Atomic Size
-As you traverse down a column on the periodic table,the size of the atom increases.
。Valence shell farther from nucleus (n increase).
。Effective nuclear charge remain the same. (Zeff = Z
– S, S = core electrons)
-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.
- Sizes of Ions
。Due to increasing value of n.
-Isoelectronic – series of atoms and ions in which the number of electrons are the same
-Consider the number of electrons and the number of protons.
-The size decreases as the nuclear charge Z increases.
- Periodic Trends in the Properties of the Elements：Ionization Energy
。Valence electron easiest to remove.
。M(g) + 1st IE → M1+(g) + 1 e-
。M+1(g) + 2nd IE → M2+(g) + 1 e-
*First ionization energy = energy to remove electron from neutral atom; 2nd IE = energy to remove from +1 ion; etc.
*1st IE < 2nd IE < 3rd IE
-It requires more energy to remove each successive electron.
-When all valence electrons have been removed, the ionization energy takes a quantum leap.
- Trends in First Ionization Energies
。Atomic radius increases
。Effective nuclear charge remains constant
。Valence electron farther from nucleus.
-As one goes across a row, the IE gets larger
。Effective nuclear charge increases.
。Decrease in atomic radius
。Valence electron nearer to the nucleus.
- Exceptions to the IE general trend
。Electrons are more difficult to remove from a complete orbitals such as ns2 and np6
-The 1st IE of the group 16 atoms (eg. O) is smaller than the 15 group atoms (eg. N).
-Electrons are more difficult to remove from half-complete orbitals such as np3 and nd5
-The 2nd IE and higher IE
Abrupt increament of IE when electron is removed from a full noble gas core configuration (ns2np6)
- Electron Affinity
-The energy involved when 1 mole of electrons is gained by 1 mole of neutral atoms in the gas phase.
M(g) + e- → M-(g) ΔE = - X kJ/mol
Cl(g) + e- → Cl-(g)ΔE = -349 kJ/mol
-Most neutral atoms and all positively charged ions,energy is released when electron is added.
。The greater the attraction between the species and the electron, the more exothermic the process
-The energy changes for adding and electron to anions and to some atoms are positive
。Work must be done to force the electron onto the species,forming an unstable anion
- General Trends in Electron Affinity
。Electrons are added less easily into the atom because of the
increase in size and there is greater repulsion from electrons already present
-EA become more negative (increases) towards the right across a period
。Electrons are added more easily into the atom because of
the smaller size
- Electronegativity
-The higher the electronegativity of an atom, the greater its attraction for the bonding electrons.
。Elements with low IE and less negative EA have low electronegativities (aka electropositive elements)
。Elements with high IE and very negative EA have high electronegativities (aka electronegative elements)
- General Trends in Electronegativity
。Increased distance between the valence electrons and the
nucleus weakens the pull of the nucleus on the electrons.
-Across a period from left to right, the electronegativity increases
。Decreased distance between the valence electrons and the
nucleus, thus stronger pull of the nucleus on the electrons.
-Fluorine is the most electronegative element (4.0) and the least electronegative element is cesium (0.7)
- Electronegativity and Bond Polarity
-The difference in electronegativity between two atoms can be
used to determine the polarity of the bonding between them.
F2 HF LiF
4.0 – 4.0 = 0 4.0 – 2.1 = 1.9 4.0 – 1.0 = 3.0
Nonpolar Polar covalent Ionic
。In F2, the electrons are shared equally between the fluorine atoms.
。In HF, the fluorine atom has a greater electronegativity than
the hydrogen atom. Unequal sharing of electrons
。In LiF, the far greater electronegativity of fluorine leads to
the complete transfer of the valence electron of Li to F.This transfer results in the formation of Li+ and F-
-If the difference in electronegativity between bonded atoms is 0 to 0.3, the bond is pure covalent.
-If the difference in electronegativity between bonded atoms 0.4 to 1.9, the bond is polar covalent.
-If the difference in electronegativity between bonded atoms larger than or equal to 2.0, the bond is ionic.
- Dipole Moments
-Polar bonds or molecules have one end slightly positive, δ+, and the other slightly negative, δ-.
。Not “full” charges, come from nonsymmetrical electron distribution.
-Dipole moment, μ, is a measure of the size of the polarity.
。Measured in debyes, D.
- Polarity of Molecules
1.Have polar bonds.
。Electronegativity difference—theory.
。Bond dipole moments—measured.
2.Have an unsymmetrical shape.
。Vector addition.
-Polarity effects the intermolecular forces of attraction.
- Molecule Polarity
-The H—O bond is polar. Both sets of bonding electrons are pulled toward the O end of the molecule. The net result is a polar molecule.
- Metallic Character
。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.
-In general, metals are found on the left of the periodic table and nonmetals on the right.
-As you traverse left to right across theperiod, the elements become less metallic.
-As you traverse down a column, the elements become more metallic.
- The Periodic Law
-The periodic table is made up of rows of elements and
columns.
。A horizontal row is called a period
*1 - 7
*Lanthanide series
*Actinide series
。A vertical column is called a group
*Roman (IA, IIA, IIIB - VIIB, VIIIB (3 columns), 1B,
IIB, IIIA – VIIIA)
*IUPAC ( 1 – 18)
*Group A elements are called representative elements
*Group B elements are called transition elements.
- Metal, Non-Metal and Metalloid
Table
-Non-Metal: Elements in the upper right corner of the
periodic Table. Their chemical and physical properties
are different from metals.
-Metalloid: Elements that lie on a diagonal line between
the Metals and non-metals. Their chemical and physical
properties are intermediate between the two.
- Groups in the Periodic Table
special names.
-These names indicate the similarities between group
members:
。Group 1A (1) : Alkali metals.
。Group 2A (2) : Alkaline earth metals.
。Group 6A (16) : Chalcogens.
。Group 7A (17) : Halogens.
。Group 8A (18) : Noble gases.
- Modern Periodic Table
-The periodic table can be used as a guide for electron
configurations.
-The period number is the value of n.
-Groups 1A and 2A (1 & 2) have the s-orbital filled.
-Groups 3A - 8A (13 - 18) have the p-orbital filled.
-Groups 3B - 2B (3 - 12) have the d-orbital filled.
-The lanthanides and actinides have the f-orbital filled.
- Electron Configuration and the Periodic Table
-The chemical behavior of elements is determined
by its electron configuration
。The elements with the same type of outer-shell
electron configuration are arranged in columns
。Elements in the same group have the same number
of valence electrons
-The principle quantum number, n, is a row in the
periodic table.
。Each period begins with a new outer electron shell
*2nd period: 1s2 2s1
*3rd period: 1s2 2s2 2p6 3s1
*4th period: 1s2 2s2 2p6 3s2 3p6 4s1
。Each period ends with a completely filled outer shell
*2nd period: 1s2 2s2 2p6
*3rd period: 1s2 2s2 2p6 3s2 3p6
*4th period: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6
- Metalloids
-For instance, silicon looks shiny, but is brittle and fairly poor conductor.
-Amphoteric oxides – oxides that exhibit both acidic and basic properties
-Amphoteric behavior:
。4Al(s) + 3O2(g) → 2Al2O3(s)(oxide)
。Al2O3(s) + 6HCl(aq) → 2AlCl3(aq) + 3H2O(l) (basic)
。Al2O3(s) + 6NaOH(aq) → 2Na3AlO3 + 3H2O(l) (acidic)
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