Copy this, think about this, and learn this, and attach it to your Bonding Lab for 16 points. Think about the words and what they mean!
BONDING LAB CONCLUSION – worth 16 points.
- Ionic compounds form between metals that lose electrons forming cations, and non metals that gain these electrons when forming into anions. Covalent bonds form when two or more nonmetals share electrons when they bond.
- Ionic bond examples include: NaCl, KBr, MgO and CuSO4. Covalent bond examples include H2O, CO2, and CH4. All atoms have an electronegativity value, which ranks their tendency to “attract” electrons when making a bond. The greater the difference in electronegativity values, the greater the bond polarity (the less nice they share the electrons. The higher value, the greater tendency to pull electrons to it’s own nucleus. This was described first by Linus Pauling.
- HONClBrIF twin is bonded to identical atoms, which have (of course) identical electronegativity values. There is NO DIFFERENCE in EN Value between identical atoms, which makes their bonds nonpolar.
- Diagrams for these diatomic elements all look like this: H-H, O=O, N≡N, Cl-Cl, Br-Br, I-I, and F-F. All are single nonpolar covalent bonds, except oxygen is a double nonpolar covalent bond, and nitrogen is a triple nonpolar covalent bond.
- CO makes a double polar covalent bond because they share two pairs of electrons, and oxygen has a higher EN Value than carbon. In order for carbon to “feel” or to “get” the octet, oxygen ‘LOANS” two electrons more to the center of the molecule so that carbon can get that octet as well. This extra pair of electrons oxygen loans is called a coordinate covalent bond.
- O3 does not fit normally as a molecule on paper with standard bonding. To describe it scientists have outlined the resonating bond. It shows that the central oxygen atom sort of makes a double bond to one other oxygen, and then the third oxygen atom sort of is just “attracted” to the central atom. This is unstable, so the bonds “switch” places, but that is also unstable. Ozone is better described as making a ‘1½ sized bond” to both of the other oxygen atoms, locking the three atoms in an unconventional bond.
- The octet rule states that when bonding, most atoms end up with 8 valence electrons in the outer orbital. Ionic bonds form when cations lose enough electrons that the next orbital is full with 8 electrons. Anions form when atoms gain enough electrons to fill the valence orbital, with 8 electrons. Some atoms, H, He, Li, Be, and B are too small to get octets. Some molecules end up with more than 8 electrons by exception, like PCl5 that gets ten valence electrons.
- If a molecule has radial symmetry, if you can cut it in half at any angle through the center an still have 2 equivalent pieces, the molecule is nonpolar. If the molecule can’t be cut in half at every angle to give two equal pieces, the molecule is polar. Ionic compounds are, by definition, polar, as they have positive and negative ions. Polar molecules include: NH3, H2O, and SCl2. Nonpolar molecules include CH4, CCl4, and CO2.
- Molecules like CH4 have polar bonds due to a difference in EN Value between H and C, but they also have radial symmetry, so their polar bonds are “balanced” from each other. CO2 and SIO2 are nonpolar molecules with polar bonds.
- NBr3 is way cool because it has nonpolar bonds (the EN Value for N and for Br are both 3.0). But due to a lack of radial symmetry, the molecule is polar.
- The 3 kinds of intermolecular bonding are: electron dispersion attraction, dipole attraction, and then hydrogen bonding. All atoms and all molecules have electron dispersion attractions. Dipole attraction need polar molecules that do NOT contain hydrogen, so CF2Br2, or SCl2, or PCl3 all have dipole attractions. Hydrogen bonding is really just SUPER DIPOLE, with hydrogen atoms. Hydrogen bonding needs polar bonds containing hydrogen in polar molecules. Examples include water, ammonia NH3, HCl, HF, or CH3Cl.
- Metallic bonds are described as packed cations within a “sea” of loose valence electrons. Metals, when pure metals, have metallic bonding. Examples include iron, gold, silver, and zinc. NaCl has the metal sodium in it, but it’s making an IONIC bond there, not a metallic bond. and Metallic bonding explain the 3 main properties of metals, which are electrical conduction, malleability and ductility. By having these loose electrons, that allows them to move, when metals are being smashed flat, or drawn into a wire, the cations would repel from each other as they got closer. When that happens, electrons that are loose flush into the squished area, keeping it neutral, and intact . It also allows the “FLOW” of electrons that is electrical current.