10-28-13

This week, we started out with review for our test. We asked a lot of questions, especially about the Lecture Chemical Bonding packets, and used class time to review.
After taking the test, it was Mole Day. We had really good cookies and hot chocolate.

  

We received a packet on Paintball and wrote about hydrogen bonding and polarity. We learned about how water’s polarity is due to the differences in electronegativity between oxygen and hydrogen. In water there is a region of partial negative charge on the side of oxygen, and a partial positive charge on the side of hydrogen. The molecules shape of bent and the polar bonds make the molecule polar overall. Hydrogen bonds occur when a hydrogen atom attaches to a small and highly electronegative atom, in this case Oxygen, in the vicinity of an atom with nonbonding electron pairs. Hydrogen bonds are the strongest of the intermolecular forces (but not as strong as covalent or ionic bonds). Hydrogen bonds are about 1/15th the strength of a covalent bond. The hydrogen bonds in water are what hold the molecule together.

We then began learning about ionic bonds, which was mostly a review. Ionic bonds are formed between two atoms when the atoms involved transfer one or more electrons to produce two charged species - positive (cation) and negative (anion). Atoms with loosely held electrons tend to form positive ions, but those who can hold additional electrons relatively strongly tend to form negative ions.

We learned about metals as well. Some properties of metals are that they have a shine or luster, can conduct heat and electricity, they're ductile, and they are malleable. Nonmetals do not have these properties - they're typically poor conductors of heat or electricity, and they aren't malleable or ductile. Electronegativity is much lower for a metal than for a nonmetal as well. In metals, the bonding is different from both covalent and ionic bonding. The electrons in their bonds are localized meaning they either are shared by a pair of atoms or they are associated with one of the two species involved in the bonding interaction. Valence electrons on a metal atom are shared with many neighboring atoms, not just one. These valence electrons are delocalized. The force of attraction between the positive metal ions and the sea of mobile negative electrons forms a metallic bond that holds these particles together.

This week, I'd rate my understanding of our topics at about a 9. It's mostly review with the ionic and covalent bonding and I feel like I understand the metals so far. I was able to help some of my classmates at my table especially with the Ionic Bonds POGIL because most of it was information that I already knew. Although, I was surprised when we were looking at the model of NaCl, that the atom for Na was the smaller particles and not actually the bigger ones. So far, I'm enjoying this topic and I hope I do better on this test than I did on the last one.