Chem Final notes

Chem Final notes - Chem Final notes Week 11/5 Videos a...

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

View Full Document Right Arrow Icon
Chem Final notes Week 11/5 Videos a. Valence electrons i. Valence electrons are all the electrons beyond the previous noble gas configuration ii. Most chemical bonding involves sharing, donating, or gaining valence electrons b. Lewis do structures i. Lewis dot structures are a shorthand method for writing valence electrons ii. The atomic symbol is written with one dot for each valence electron iii. For most elements, eight valence electrons gives an especially stable configuration. c. Predicting reactivity i. Elements usually react in set ratios to form neutral compounds where each atom has a full octet ii. An ionic bond forms when on atom gives electrons to another atom iii. A covalent bond forms when two atoms share electrons d. Predicting chemical formulas i. Ionic compounds are composed of anions and cations joined by strong bonds ii. The anions and cations are present in stoichiometric ratios that cause the overall charges to the balance e. Born-Haber cycle i. The Born-Haber cycle allows for the calculation of lattice energy yfor an ionic compound ii. A special application of Hess’s Law f. Lattice energy i. Lattice energy – the energy required to break an ionic solid into its constituent gaseous ions: AX (s) Aⁿ+ (g) + Xⁿ- (g) ii. Ionic compounds tend to exist as crystalline solids in a regular lattice of alternating cations and anions iii. The Coulomb force changes with the square of the changes involved iv. Lattice energy is the energy required to break an ionic solid into its constituent gaseous ions v. Lattice energy depends on the Coulomb force between the ions g. Polyatomic ions i. Polyatomic ions are composed of two or more chemically bonded atoms ii. Ionic bonding is an interaction between a cation and an anion. These species can be monatomic ions or polyatomic ions iii. General properties of ionic compounds: 1. strong bonds 2. hard crystals 3. high melting points 4. contain ions in stoichiometric ratios that give neutral compounds iv. Common examples: 1. fertilizer
Background image of page 1

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

View Full Document Right Arrow Icon
2. plaster of paris 3. laundry detergent Born-Haber 1) sublimation energy 2) dissociation energy (Cl2 Cl put energy in to break the bonds) 3) ionization energy to turn into an ion ( + for cation) 4) ionization energy to turn into an ion ( - for anion) 5) condensation of gaseous ions to form ionic lattice ( - lattice energy) Hess’s Law, backwards and forwards h. The octet rule i. Provides a powerful tool for predicting how the electrons should be distributed around a molecule ii. A complete octet in the outer shell is more stable because it give oxygen a noble gas configuration iii. The octet rule states that nonmetal atoms are most stable in molecules when surrounded by eight electrons iv. Remember that hydrogen and helium can only want 2 electrons in their valence shell ( duet rule – applies only to 1 st period) v. Lewis bonding theory predicts how atoms come together to for stable molecules vi. Non-bonding atoms are called “lone pairs” (important later)
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page1 / 7

Chem Final notes - Chem Final notes Week 11/5 Videos a...

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