Chemistry Lecture Notes

Chemistry Lecture Notes - 09/27/07 Law of constant...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 09/27/07 Law of constant composition Ex) water: H20 =2H +O Law of conservation of mass(matter) : allows us to explain many chemical reactions. (Atoms can neither be created nor be destroyed) Ex) 2HgO + Heat 2 Hg(l) + O2 (g); 100g 100g Law of conservation of energy: Matter/energy can neither be created nor be destryoed, but rather, they are transformed into other forms of structures. 10/02/07- Bonding occurs because sum is lower in E than isolated atom.- Atoms tend to be stable and to spend minimum energy level- Gain/lose of energy is the reason that bond forms and reactions occur.- Energy is the reason bonding and reactions occur; usually products are lower in energy than reactants Bonding (Stoichiometric relationship) Classical description of bonding- Bonding is the glue that holds different atoms together; it involves one of two types of things- Electrostatics ( +/-) charge differentials- Sharing of electrons- Bonding helps us to explain chemical reactivity & chemical formulas Classical bonding motifs- Pure Ionic ( +/-) = electrostatics- Covalent (Sharing e-) electrons do not have to be shared equally. (Dots for unattached electrons, lines for attaches ones)- Metallic (ex) Au: Metal cations are surrounded by flowing e-s (Molecular orbital theory) Picture:- Coordinate covalent (ex) NH4+BF3 in this reaction process, electrons are conditionally shared. It has characteristics of both ionic and - Polar covalent consists of covalent and ionic characteristics. o More covalent a bond is, more dipole moment, and less polarization of molecules.- Most of the bonds are neither pure covalent, nor pure ionic, but rather, they are having both characteristics.- When the system breaks apart, it breaks a part only in one way. Electrons- Core electrons (2): that are preserved for balance of atoms- Valence electrons (8): that are responsible for bondings. Ionization energy (IE): Amount of energy to required to remove an electron from a gaseous neutral atom states; E is positive if E must be added.- If E is given all IEs are always positive because it takes E to remove an electron. IE is always less then IE 2 .- We are removing e- from an atom so IE 2 is much more positive then IE. o Ex) A childs handful candies IE<IE 2 < < <IE 3- In order to remove an electron from an atom whose valence electron has 2, 10, 18, 32, the core configuration requires very very high - Its difficult to remove electrons (IE increases )- IE is always positive because we have to add energy to remove e- s- E is positive if energy is added, and E is negative when energy is given off- In parallel metallic character, metals have low IE, but non-metals have very high IE....
View Full Document

Page1 / 39

Chemistry Lecture Notes - 09/27/07 Law of constant...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online