Bonding atoms achieve a stable number of electrons (ionic and covalent) involves valence (outer) electrons make compounds and/or solids fill out types of bonding chart using overhead show overhead of metallic bonding draw examples of ionic bonding – use skeletal models - MgO, NaCl, CaCl2, K2S draw examples of covalent bonding – use skeletal models – CO2, H2O, O2

Metallic Bonding All pure metals have metallic bonding and therefore exist as metallic structures.  Metallic bonding consists of a regular arrangement of positive ion cores of the metals surrounded by a mobile delocalized sea of electrons.

Metallic Bonding Each atom donates its valence electrons to the whole Atom therefore becomes a cation (here called an ion core) Donated electrons form an electron cloud surrounding all the ion cores Electron cloud binds all the ion cores together by coulombic forces

Metallic Bonding Valence electrons are delocalized: Shared by all atoms in the material Electrons are free to drift throughout the material Provides unique properties only found in metals shiny metallic luster good electrical and thermal conductivity many others ...

Metallic Bonds: Mellow dogs with plenty of bones to go around These bonds are best imagined as a room full of puppies who have plenty of bones to go around and are not possessive of any one particular bone.  This allows the electrons to move through the substance with little restriction.  The model is often described as the "kernels of atoms in a sea of electrons." http://ithacasciencezone.com/chemzone/lessons/03bonding/dogbonds.htm

Ionic Bonding (ceramics and polymers)

Ionic bonding can be best imagined as one big greedy Ionic Bonds: One big greedy thief dog! Ionic bonding can be best imagined as one big greedy dog stealing the other dog's bone.  If the bone represents the electron that is up for grabs, then when the big dog gains an electron he becomes negatively charged and the little dog who lost the electron becomes positively charged.  The two ions (that's where the name ionic comes from) are attracted very strongly to each other as a result of the opposite charges. http://library.tedankara.k12.tr/webchem/Chemical%20bonding%20and%20intermolecular%20forces/ICSD%20Bonding/Bonding%20by%20Analogy%20Dog%20-%20Bone%20Bonds.mht

Sodium lets Chlorine use its valance electron

Covalent Bonding (Ceramics)

Covalent bonds can be thought of as two or more dogs Covalent Bonds: Dogs of equal strength. Covalent bonds can be thought of as two or more dogs with equal attraction to the bones.  Since the dogs (atoms) are identical, then the dogs share the pairs of available bones evenly.  Since one dog does not have more of the bone than the other dog, the charge is evenly distributed among both dogs.  The molecule is not "polar" meaning one side does not have more charge than the other.

These bonds can be thought of as two or more dogs that Polar Covalent Bonds: Unevenly matched but willing to share. These bonds can be thought of as two or more dogs that have different desire for bones.  The bigger dog has more strength to possess a larger portion of the bones.  Sharing still takes place but is an uneven sharing.  In the case of the atoms, the electrons spend more time on the end of the molecule near the atom with the greater electronegativity (desire for the electron) making it seem more negative and the other end of the molecule seem more positive.

http://www. matsceng. ohio-state http://www.matsceng.ohio-state.edu/mse205/lectures/chapter2/chap2_slide9.htm

Covalent Network Solid only covalent bonds extremely large molecules or networks usually have at least one element from carbon family very strong and hard very high melt T° some glass and ceramics, diamond polymers are usually not because they make linear chains instead of networks

intermolecular forces high melt temps, nonconductors as solids, Type of bonding metallic ionic covalent intermolecular forces Type of elements used Between metals Metals and nonmetals Between nonmetals Between molecules Givers &/or takers of electrons Between givers Between givers and takers Between takers Description Valence e- roam freely between many atoms (delocalized). Sea of e- surrounding (+) kernels. Transfer e- Makes (+) and (-) ions that are attracted to each other. Share e- Forms discrete molecules. Hold covalently bonded molecules together as a solid. Type of material formed Solid metallic elements and alloys Ceramics and glass Polymers and some ceramics/glasses Helps form solid polymers Strength of bond Relatively strong Very strong Weak Properties Produced Good conductors, workable, corrode easily, generally high melt temps but variable Brittle, high melt temps, nonconductors as solids, don’t corrode Insulators, Help determine a lot of properties of covalent compounds (polymers). Soft and plastic

Molecular formula

Molecular formula   Coefficient Subscript

Identify number of atoms in the formula Identify for the whole formula and for each element. See NOTEBOOK for more detail.

Balancing equations

Electronic Configuration

Quantum Numbers When describing orbitals and their components quantum mechanics uses 3 quantum numbers: n l ms

Quantum number n Represents the energy level and its value (always a positive whole number).

Quantum number l Identifies the energy sublevel and the shape of the orbital. Value goes from 0 and n-1.

Quantum number ml Describes the space orientation of the orbitals. Values go from -1 to +1, including 0.

Quantum number ms Describes the spin of the electron in an orbital.

Energy levels Energy Level Number of Electrons 1 2 8 3 18 4 32 5 6 7

Energy sublevels Energy Level Energy Sublevel 1 2 3 4 5 6 7

Electron Orbitals Orbital Number of Electrons s 2 p 6 d 10 f 14

Electronic Configuration Distribution and organization of the electrons throughout the orbitals of an atom. When completing the electronic configuration of an atom we have to consider three rules. Aufbau Principal Pauli's Exclusion Principal Hund's Rule

Aufbau Principal According to this rule, electrons occupy the orbitals of lowest energy first. The orbitals of any sublevel are of equal energy.

Pauli’s Exclusion Principal This rule establishes that an orbital can have at most 2 electrons, but these electrons have to have opposite spins. e- #1 – arrow looking up (clockwise spin) e- #2 – arrow looking down (counterclockwise spin)

Hund’s Rule This rule states that electrons that are on the same energy sublevel, need to fill all the orbitals with the same spin and then complete with the opposite electron.

Examples

Practice!!!

Coming topics: Nomenclature and Lewis Structure