Big Idea #2 Flashcards
(30 cards)
Ionic Bonding occurs between _____ and _____
metals, nonmetals
What are some properties of ionic bonded compounds?
solid at room temperature, very high melting/boiling points, salts are an example
What are factors that affect the melting points of ionic substances?
- charge on the ions (greater charge, greater bond energy)
- size of the ions (smaller ions have greater Coulomb attraction)
Where are the electrons in an ionic solid?
each electron is localized around a particular atom, so electrons don’t move around the lattice
What’s a difference between an ionic solid and an ionic liquid?
ionic solids are poor conductors of electricity while ionic liquids can conduct electricity because the ions themselves are free to move around
Where are the electrons in a metal?
A sea of electrons model can be used in this case. The positively charged core (nucleus, core electrons) is stationary while the valence electrons don’t belong to a specific atom an are mobile. Their delocalized structure also explains why they’re malleable.
How do metals bond to form alloys?
When two metals are melted into their liquid phases and are then poured together before cooling.
What are characteristics of an interstitial alloy?
Metal atoms with vastly different radii combine, ex. steel (carbon & iron)
What are characteristics of a substitutional alloy?
Metal atoms with similar atom radii combine, ex. brass (copper & zinc)
The first covalent bond formed between two atoms and all single bonds are _____
sigma bonds
The second bond in a double bond and the second and third bond in a triple bond are ____
pi bonds
What are characteristics of Network Covalent Bonds?
Atoms are held together in a lattice of covalent bonds. Very hard with very high melting and boiling points. Electrons are localized between particular atoms so these solids are not good conductors of electricity. Usually are compounds of carbon.
What is doping?
A process in which an impurity is added to an existing lattice. In a silicon lattice, the silicon atoms are replaced with elements that have only three valence electrons and the neighboring bonds will lack one bond apiece. The missing bond creates a positive charge which attracts other electrons, increasing conductivity. This is specifically called p-doping.
What is n-doping?
An element with five valence electrons is sued to add impurities to a silicon lattice there is an extra valence electron that is free to move around the lattice, causing an overall negative charge that increases the conductivity of the silicon.
What are dipole-dipole forces?
Forces that occur between polar molecules. The positive end of one polar molecule is attracted to the negative end of another polar molecule. Greater polarity, stronger dipole-dipole forces.
What are hydrogen bonds?
Special dipole-dipole attractions where the positively charged hydrogen end of a molecule is attracted to the negatively charged end of either a Fluorine, Oxygen or Nitrogen.
What are london dispersion forces?
Very weak attractions that occur between all molecules due to the random motions of electrons on atoms within molecules. Molecules with more electrons have larger forces.
IMF Rankings
- Hydrogen Bonds
- Non-Hydrogen Bon Permanent Dipoles
- London Dispersion Forces
What’s the relationship between IMFs and states?
Substances with weak IMFs tend to be gases at room temperature and substances that exhibit strong IMFs tend to be liquids at room temperature
What are characteristics of vapor pressure?
Molecules inside a liquid are in constant motion, if molecules hit the surface of the liquid with enough kinetic energy they can escape the IMFs and transition to the gas phase (vaporization). Direct relationship between temperature and vapor pressure.
When can a molecule have an expanded octet?
Molecules that have d subshells, but never more than 12 electrons
How do you calculate formal charge?
Take the number of valence electrons for the atom and subtract the number of assigned electrons in the lewis structure
Assumptions of Kinetic Molecular Theory
- KE is directly proportional to its temperature
- If several different gases are in a sample, they will all have the same KE
- Volume of a gas is insignificant
- Not IMFs between gases
- Gases are in constant motion and collide with each other with out losing energy
If Volume is constant: As pressure ____, temperature ____ and vice versa
increases, increases
