Chapter 8: Basic Concepts of Chemical Bonding Flashcards
What is a covalent bond?
A covalent bond refers to a pair of shared electrons between two atoms (2 nonmetals usually.)
What is the relationship on the PTE in regards to electronegativity?
L-R and D-U is an increase in electronegativity.
What group is the only except to the rules of electronegativity in regards to the PTE?
Noble gases
What is the most electronegative element?
Fluorine
What is least electronegative element?
Cesium and Francium
What defines the polarity of a molecule?
The bigger the difference in electronegativity between two atoms, the more polar the bond.
What range must the difference in polarity be in order for a molecule to be considered “Purely covalent?”
0<0.4
What range in difference of electronegativity encompasses the “polar covalence?”
.4<1.6
What range is considered ionic?
x>1.6
What happens to the electronegativity when an element loses an electron?
The electronegativity becomes more negative, meaning less electronegativity, meaning it is more likely to share electrons with other elements.
What is lattice energy?
The energy associated with electrostatic interactions. It is governed by Coulomb’s Laws.
Define the terms in the following equation for Lattice Energy: Ele = k (Q1Q2/d)
Eel = Lattice Energy
k = 8.99x10^9J*M/C
d = distance from the nucleus of one atom to the other
Q1 /2 = Charges on both atoms/elements
The greater the difference in electronegativity, the more _____ the bond.
Polar
How does one decide which atom becomes the central atom of a molecule?
It is the least electronegative and/or has the highest capacity to share electrons.
Define “Electron affinity”
The amount of energy released when an electron is added to an element or atom.
The 6 steps for drawing Lewis Structures
- Count up formal charges, adding one if the molecule is a negative ion and subtracting if it is positive.
- Determine the central atom based on which atom has the lowest EN and highest bonding sites
- Fill the octets of the outermost atoms first.
- Put the remaining electrons on the central atom in pairs
- If you run out of electrons before the central atom has a complete octet, start forming multiple bonds.
- If a central atom has more than an octet, it is okay if it’s in the third period or beyond
- Optimize the formal charge
How many valence electrons does Boron have?
6, for some reason.
How does one calculate formal charge?
of VE - (# of paired, non-bonded electrons + # of bonds)
What is the typical behavior of metals and their electrons?
They tend to get rid of electrons to become a positive ion.
Covalent bonds are more common amongst _________ and __________ and are, thus, more likely to _____ electrons.
metals and metalloids are more likely to share electrons.
Halogens are generally attracted to ____ _____, which means energy is required to ________ them.
each other and energy is required to separate them.
Exceptions to the octet rule
- Odd number of electrons
- Less than an octet.
- Atom in the third period and beyond.
