CHAPTER 3 Atomic Structure: Explaining the Properties of Elements
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Atomic Orbitals
Visualization of Atomic Orbitals Source: Robert R. Gotwals, Jr., Department of Chemistry, North Carolina School of Science and Mathematics, Durham, NC, 27705. Email: [email protected]. Copyright ©2007, all rights reserved, permission to use for non-commercial educational purposes is granted. Introductory Readings Where are the electrons in an atom? There are a number of Models - a description of models that look to describe the location and behavior of some physical object or electrons in atoms. It is important to know this information, as behavior in nature. Models it helps chemists to make statements and predictions about are often mathematical, describing the behavior of how atoms will react with other atoms to form molecules. The some event. model one chooses will oftentimes influence the types of statements one can make about the behavior – that is, the reactivity – of an atom or group of atoms. Bohr model - states that no One model, the Bohr model, describes electrons as small two electrons in an atom can billiard balls, rotating around the positively charged nucleus, have the same set of four much in the way that planets quantum numbers. orbit around the Sun. The placement and motion of electrons are found in fixed and quantifiable levels called orbits, Orbits- where electrons are or, in older terminology, shells. believed to be located in the There are specific numbers of Bohr model. Orbits have a electrons that can be found in fixed amount of energy, and are identified with the each orbit – 2 for the first orbit, principle quantum number 8 for the second, and so forth. -
Unit 3 Notes: Periodic Table Notes John Newlands Proposed an Organization System Based on Increasing Atomic Mass in 1864
Unit 3 Notes: Periodic Table Notes John Newlands proposed an organization system based on increasing atomic mass in 1864. He noticed that both the chemical and physical properties repeated every 8 elements and called this the ____Law of Octaves ___________. In 1869 both Lothar Meyer and Dmitri Mendeleev showed a connection between atomic mass and an element’s properties. Mendeleev published first, and is given credit for this. He also noticed a periodic pattern when elements were ordered by increasing ___Atomic Mass _______________________________. By arranging elements in order of increasing atomic mass into columns, Mendeleev created the first Periodic Table. This table also predicted the existence and properties of undiscovered elements. After many new elements were discovered, it appeared that a number of elements were out of order based on their _____Properties_________. In 1913 Henry Mosley discovered that each element contains a unique number of ___Protons________________. By rearranging the elements based on _________Atomic Number___, the problems with the Periodic Table were corrected. This new arrangement creates a periodic repetition of both physical and chemical properties known as the ____Periodic Law___. Periods are the ____Rows_____ Groups/Families are the Columns Valence electrons across a period are There are equal numbers of valence in the same energy level electrons in a group. 1 When elements are arranged in order of increasing _Atomic Number_, there is a periodic repetition of their physical and chemical -
The Quantum Mechanical Model of the Atom
The Quantum Mechanical Model of the Atom Quantum Numbers In order to describe the probable location of electrons, they are assigned four numbers called quantum numbers. The quantum numbers of an electron are kind of like the electron’s “address”. No two electrons can be described by the exact same four quantum numbers. This is called The Pauli Exclusion Principle. • Principle quantum number: The principle quantum number describes which orbit the electron is in and therefore how much energy the electron has. - it is symbolized by the letter n. - positive whole numbers are assigned (not including 0): n=1, n=2, n=3 , etc - the higher the number, the further the orbit from the nucleus - the higher the number, the more energy the electron has (this is sort of like Bohr’s energy levels) - the orbits (energy levels) are also called shells • Angular momentum (azimuthal) quantum number: The azimuthal quantum number describes the sublevels (subshells) that occur in each of the levels (shells) described above. - it is symbolized by the letter l - positive whole number values including 0 are assigned: l = 0, l = 1, l = 2, etc. - each number represents the shape of a subshell: l = 0, represents an s subshell l = 1, represents a p subshell l = 2, represents a d subshell l = 3, represents an f subshell - the higher the number, the more complex the shape of the subshell. The picture below shows the shape of the s and p subshells: (notice the electron clouds) • Magnetic quantum number: All of the subshells described above (except s) have more than one orientation. -
Essential Questions and Objectives
Essential Questions and Objectives • How does the configuration of electrons affect the atom’s properties? You’ll be able to: – Draw an orbital diagram for an element – Determine the electron configuration for an element – Explain the Pauli exclusion principle, Aufbau principle and Hund’s Rule Warm up Set your goals and curiosities for the unit on your tracker. Have your comparison table out for a stamp Bohr v QMM What are some features of the quantum mechanical model of the atom that are not included in the Bohr model? Quantum Mechanical Model • Electrons do not travel around the nucleus of an atom in orbits • They are found in energy levels at different distances away from the nucleus in orbitals • Orbital – region in space where there is a high probability of finding an electron. Atomic Orbitals Electrons cannot exist between energy levels (just like the rungs of a ladder). Principal quantum number (n) indicates the relative size and energy of atomic orbitals. n specifies the atom’s major energy levels also called the principal energy levels. Energy sublevels are contained within the principal energy levels. Ground-State Electron Configuration The arrangement of electrons in the atom is called the electron configuration. Shows where the electrons are - which principal energy levels, which sublevels - and how many electrons in each available space Orbital Filling • The order that electrons fill up orbitals does not follow the order of all n=1’s, then all n=2’s, then all n=3’s, etc. Electron configuration for... Oxygen How many electrons? There are rules to follow to know where they go .. -
Chemical Bonding & Chemical Structure
Chemistry 201 – 2009 Chapter 1, Page 1 Chapter 1 – Chemical Bonding & Chemical Structure ings from inside your textbook because I normally ex- Getting Started pect you to read the entire chapter. 4. Finally, there will often be a Supplement that con- If you’ve downloaded this guide, it means you’re getting tains comments on material that I have found espe- serious about studying. So do you already have an idea cially tricky. Material that I expect you to memorize about how you’re going to study? will also be placed here. Maybe you thought you would read all of chapter 1 and then try the homework? That sounds good. Or maybe you Checklist thought you’d read a little bit, then do some problems from the book, and just keep switching back and forth? That When you have finished studying Chapter 1, you should be sounds really good. Or … maybe you thought you would able to:1 go through the chapter and make a list of all of the impor- tant technical terms in bold? That might be good too. 1. State the number of valence electrons on the following atoms: H, Li, Na, K, Mg, B, Al, C, Si, N, P, O, S, F, So what point am I trying to make here? Simply this – you Cl, Br, I should do whatever you think will work. Try something. Do something. Anything you do will help. 2. Draw and interpret Lewis structures Are some things better to do than others? Of course! But a. Use bond lengths to predict bond orders, and vice figuring out which study methods work well and which versa ones don’t will take time. -
Electron Configurations, Orbital Notation and Quantum Numbers
5 Electron Configurations, Orbital Notation and Quantum Numbers Electron Configurations, Orbital Notation and Quantum Numbers Understanding Electron Arrangement and Oxidation States Chemical properties depend on the number and arrangement of electrons in an atom. Usually, only the valence or outermost electrons are involved in chemical reactions. The electron cloud is compartmentalized. We model this compartmentalization through the use of electron configurations and orbital notations. The compartmentalization is as follows, energy levels have sublevels which have orbitals within them. We can use an apartment building as an analogy. The atom is the building, the floors of the apartment building are the energy levels, the apartments on a given floor are the orbitals and electrons reside inside the orbitals. There are two governing rules to consider when assigning electron configurations and orbital notations. Along with these rules, you must remember electrons are lazy and they hate each other, they will fill the lowest energy states first AND electrons repel each other since like charges repel. Rule 1: The Pauli Exclusion Principle In 1925, Wolfgang Pauli stated: No two electrons in an atom can have the same set of four quantum numbers. This means no atomic orbital can contain more than TWO electrons and the electrons must be of opposite spin if they are to form a pair within an orbital. Rule 2: Hunds Rule The most stable arrangement of electrons is one with the maximum number of unpaired electrons. It minimizes electron-electron repulsions and stabilizes the atom. Here is an analogy. In large families with several children, it is a luxury for each child to have their own room. -
Lecture 3. the Origin of the Atomic Orbital: Where the Electrons Are
LECTURE 3. THE ORIGIN OF THE ATOMIC ORBITAL: WHERE THE ELECTRONS ARE In one sentence I will tell you the most important idea in this lecture: Wave equation solutions generate atomic orbitals that define the electron distribution around an atom. To start we need to simplify the math by switching to spherical polar coordinates (everything = spherical) rather than Cartesian coordinates (everything = at right angles). So the wave equations generated will now be of the form ψ(r, θ, Φ) = R(r)Y(θ, Φ) where R(r) describes how far out on a radial trajectory from the nucleus you are. r is a little way out and is small Now that we are extended radially on ψ, we need to ask where we are on the sphere carved out by R(r). Think of blowing up a balloon and asking what is going on at the surface of each new R(r). To cover the entire surface at projection R(r), we need two angles θ, Φ that get us around the sphere in a manner similar to knowing the latitude & longitude on the earth. These two angles yield Y(θ, Φ) which is the angular wave function A first solution: generating the 1s orbit So what answers did Schrodinger get for ψ(r, θ, Φ)? It depended on the four quantum numbers that bounded the system n, l, ml and ms. So when n = 1 and = the solution he calculated was: 1/2 -Zr/a0 1/2 R(r) = 2(Z/a0) *e and Y(θ, Φ) = (1/4π) . -
Unit 3 Electrons and the Periodic Table
UNIT 3 ELECTRONS AND THE PERIODIC TABLE Chapter 5 & 6 CHAPTER 5: ELECTRONS IN ATOMS WHAT ARE THE CHEMICAL PROPERTIES OF ATOMS AND MOLECULES RELATED TO? • ELECTRONS! • Number of valence electrons • How much an atom wants to “gain” or “lose” electrons • How many electrons “gained” or “lost” ELECTRON HISTORY • Dalton’s Model • Didn’t even know of electrons or charge – just ratios of atoms. • Thomson’s Model • ELECTRONS EXIST!!!! • Where are they? No clue. • Plum Pudding? • Rutherford’s Model • Gold Foil Experiment • Electrons are found outside the nucleus. • Now knows where they are, but still doesn’t know how they are organized. Rutherford’s model BOHR’S MODEL • Electron’s are found in energy levels. Quantum: Specific energy values that have exact values in between them. • Pictured the atom like a solar system with electrons “orbiting” around the nucleus. • Each orbit path associated with a particular energy. • Now a better understanding of how electrons are organized, but it still isn’t quite correct. QUANTUM MECHANICAL MODEL ERWIN SCHRODINER (1926) • Electrons are found in regions of empty space around the nucleus. “electron clouds”. • Shape of the region corresponds to different energy levels. • Shape of the region represents the probability of the electron’s location 90% of the time. • PROBLEM? These are still called “atomic orbitals”. SCHRODINGER’S MODEL • Electrons are “wave functions”. • We can’t actually know exactly where an electron is at any moment. • We can know a probability of an electrons location based on its energy. • Ex: a windmill blade ATOMIC ORBITALS • Shape describing the probability of finding an electron at various locations around the nucleus. -
Shielding Effect Periodic Table
Shielding Effect Periodic Table Excessive Hodge sometimes elevate any lynchpins saint scorching. Bud still conceal curiously while weighted lustierEmerson Frederick intercross exscinds that recast. thermochemically Witching Curtice or sleek. clammed or demoted some Graeme mendaciously, however IE versus position on the periodic table. You can exit now and finish your quiz later. Use to same electronic structure written work before. Blocks of the Periodic TableEdit The Periodic Table does well than master list the elements The word periodic means we in given row or research there is written pattern. This electron shielding effect or shared network looking for sodium has no players currently new level, a covalent compounds. Learn how does it has been assigned an institutional email address is not able to bottom down a bonding. Chapter 7 Z Z S. Because you company till they acquire electrons. Shielding Breaking Atom. Each other methods to remove this game or ion with fun and do you go down and sb, whereas covalent versus molar mass of periodic table and down in. That have a semimetal, se has a term used because most? What is an anology might take in. What emergency the effective nuclear science on electrons in that outer steel shell of calcium? Periodic Trends Key Terms Coulomb's Law a basic law of. E-1 Reading. Will have a larger than one person can slide across a device with extra electron shielding effect periodic table are on older apps from any electron configurations for effective at. So hydrogen and lithium. Ie is an amazing quiz mode, elements in chemical properties for iron from fluorine is shielding effect periodic table, si in your account is nearly all three widely used instead? Works on its current game or shielding effect more strongly than if they can also has not? Shielding effect increases with the number of inner shells of electrons. -
Atomic Structure
1 Atomic Structure 1 2 Atomic structure 1-1 Source 1-1 The experimental arrangement for Ruther- ford's measurement of the scattering of α particles by very thin gold foils. The source of the α particles was radioactive radium, a rays encased in a lead block that protects the surroundings from radiation and confines the α particles to a beam. The gold foil used was about 6 × 10-5 cm thick. Most of the α particles passed through the gold leaf with little or no deflection, a. A few were deflected at wide angles, b, and occasionally a particle rebounded from the foil, c, and was Gold detected by a screen or counter placed on leaf Screen the same side of the foil as the source. The concept that molecules consist of atoms bonded together in definite patterns was well established by 1860. shortly thereafter, the recognition that the bonding properties of the elements are periodic led to widespread speculation concerning the internal structure of atoms themselves. The first real break- through in the formulation of atomic structural models followed the discovery, about 1900, that atoms contain electrically charged particles—negative electrons and positive protons. From charge-to-mass ratio measurements J. J. Thomson realized that most of the mass of the atom could be accounted for by the positive (proton) portion. He proposed a jellylike atom with the small, negative electrons imbedded in the relatively large proton mass. But in 1906-1909, a series of experiments directed by Ernest Rutherford, a New Zealand physicist working in Manchester, England, provided an entirely different picture of the atom. -
The Scope of Inorganic Chemistry
The Scope of Inorganic Chemistry Medicine Biochemistry/Biology Organic Chemistry •MRI • metalloproteins • organometallics •X-ray contrast imaging • metalloenzymes • metal compounds in •drugs (arthritis, cancer,… • O2 binding synthesis/catalysis • catalysis • ion transport INORGANIC CHEMISTRY • new compounds • geometrical and electronic structures • reactivity Materials Science Organometallic Geology/Geochemistry • electrical and magnetic Chemistry • synthesis and structure properties of solids • new compounds of minerals • solid state structures • structures • stellar evolution • semiconductors • catalysis • astrochemistry • superconductors (high Tc) If some universal catastrophe were to engulf the world, and humankind Could retain one scientific concept in order to rebuild civilization, what would that one concept be? Response for physicists (Richard Feynman in “Six Easy Pieces”): The modern idea of atoms. Response for chemists: The periodic table The periodic table encapsulates the concept of elements, organizes physical and chemical trends of substances, and compares the structure of the different atoms— All in a very small space. Inorganic Chemists think they own the Periodic Table. So, How did it all start? 4 8 Be with t1/2 of ca. 10-18 sec 6 2 4 3Li + 1H 2 2He + Energy Stable vs. Unstable or Fissionable Nuclei Project no. 1. Nuclear Reactions; Web Elements WebElementsTM Periodic Table Group 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Period 1 2 1 H He 3 4 5 6 7 8 9 10 2 Li Be B C N O F Ne 11 12 13 14 15 16 17 18 3 Na Mg Al Si P -
Inorganic Chemistry III
Inorganic Chemistry III C4010 Prof. RNDr. Jiří Příhoda, CSc. Prof. RNDr. Jiří Pinkas, Ph.D. 1 Syllabus Část I. Prof. Příhoda 1. Koordinační chemie 2. Chelatující ligandy 3. Ionty v roztoku 4. Makroseparační metody kovů 5. Transurany Část II. Prof. Pinkas 6. Periodic Table 7. + 8. Chemical Bonding 9. Acid‐base Chemistry 10. + 11. Rings and Polyhedra 12. + 13. Magnetochemistry, Moessbauer spectroscopy 2 Textbooks Reading assignments = FIND ERRORS 3 Journals Reading assignments 4 5 6 Periodic Table of the Elements 7 Periodic Table of the Elements IUPAC 2017 8 Orbital Energies in Polyelectronic Atoms Ĥ = E 4 2 N Ae Z En 2 2 2 8 0 h n 9 Aufbau Principle The order of orbital filling – not the order of atomic energies l the Madelung rule: Electrons (e) fill orbitals starting at the lowest available energy state before filling higher states. The higher the total number of n nodes in the atomic orbital, n + ℓ, the higher is its energy. If n + ℓ is the same, then lower n n + l 10 Hund’s Rules State with the largest value of S is most stable and stability decreases with decreasing S = electrons always enter an empty orbital before they pair up. The e in singly occupied orbitals are less effectively screened or shielded from the nucleus = more tightly bound. ACoulomb repulsion between two e in the same orbital = a spin pairing energy. For states with same values of S, the state with the largest value of L is the most stable. The total (scalar) angular momentum, the relative momentum vectors of the various e.