Chapter 1 Flashcards
Summarize the 3 unique features of Carbon
- C is a small atom
- intermediate electronegativity (2.5)
- covalently bonds with CHONS, the halogens, and some metals
Atoms contain a small dense _________ where the ________/______ are located surrounded by the ________
nucleus
protons/neutrons
electron cloud
Electrons are configured into regions of space called ____________ (____) that hold _________ electrons each
principle energy levels (shells)
2n^2
How many electrons are held in each of shells 1 through 4?
1 - 2e
2- 8e
3 - 18e
4 - 32e
Shells are divided into sub-shells called ________ designated by letters . . .
orbitals
s, p, d
List how many orbitals occur in each shell.
s - one per shell
p - set of 3 per shell 2 and up
d - set of 5 per shell 3 and up
What is the Aufbau principle?
Orbitals fill in order of increasing energy from lowest to highest
What is the Pauli exclusion principle?
Each orbital can hold up to two electrons with their spinning directions oppositely paired
What is the Pauli principle?
We add one electron to each equivalent (degenerate) orbital before adding a second electron to ANY of them
How do atoms bond according to the Lewis model of bonding?
Atoms bond so that each atom in the bond acquires the e- configuration of the noble gas nearest it.
- atoms that gain e- become anions
- atoms that lose e- become cations
What’s the difference between an ionic and covalent bond?
Ionic bonds result from the electrostatic attraction of an anion and cation while covalent bonds result from two atoms sharing one or more of the e- pairs
Define electronegativity and the trend it follows.
A measure of the force of an atom’s attraction for the electrons it shares in a chemical bond with another atom. It increases moving right and up (towards F) on the periodic table
An E.neg difference of less than 0.5 indicates a . . .
nonpolar covalent bond
An E.neg difference of 0.5 to 1.9 indicates a . . .
polar covalent bond
An E.neg difference greater than 1.9 indicates a . . .
Ionic bond (commonly seen between a metal and nonmetal)
An ionic bond forms from the ________ from the valence shell of an atom with ______ E.neg to the valence shell of an atom with _______ E.neg and is represented by a . . .
transfer of e-
lower
higher
single-headed curved arrow
A covalent bond forms when _________ to complete the valence shell of either atom
e- pairs are shared
In a polar covalent bond the more electronegative atom has a ________ charge while the less electronegative atom has a _________ charge. This is reflected in the bond-dipole arrow always pointing from . . .
partial negative
partial positive
positive to negative
Define formal charge and the equation to calculate it.
The charge on an atom in a molecule or polyatomic ion.
formal charge = # of valence e- in a neutral, unbonded atom - (all unshared e- + # of bonds)
Note that double bonds = 2 in this case
If the formal charge is less than that assigned to the unbonded atom, the atom has a ______ formal charge.
positive
If the formal charge is greater than that assigned to the unbonded atom, the atom has a ______ formal charge.
negative
A molecule with a polar bond can be non-polar if . . .
The vector sum of its dipoles is zero (they cancel each other out)
________ is a way to describe molecules and ions for which no single Lewis structure provides a fully accurate representation
Resonance
Individual Lewis structures in Resonance models are called _________________. The molecule or ion is a hybrid of the various structures.
contributing structures
