Chem test 1 Flashcards
What is the Lewis structure?
an empirically based method of drawing molecular structures.
How many electrons does 1 bond represent?
2
how many electrons does a double bond represent?
4
How many electrons does a triple bond represent?
6
What is the name of the structures used for organic chemistry?
Bond-Angle structures
What are the steps to drawing a lewis structure for an element?
- Determine number of valance electrons by writing out the orbitals
- draw the chemical symbol
- place one dot around each side of the chemical symbol
- any remaining electrons are paired until no electrons remain
How do you denote an anion in the lewis structure?
By adding it’s appropriate number of electrons and then adding a - sign in the subscript.
Can also put the whole structure in brackets and then add the negative sign.
Which are the odd elements and are happy without fulfilling the octet rule?
H
He
B
Al
Which elements can have expanded octets?
Elements in period 3 and higher (4,5,6, etc.)
What are the steps to drawing a lewis structure of a molecular compound?
- count the total number of valence electrons
- drawa skeletal structure (central atom + peripheral atoms + bonds)
- Fill octets of peripheral atoms by adding lone pair electrons
- Place any remaining electrons to the central atom as a lone pair
Count all electrons to make sure you’ve used them all - calculate any formal charges
- adjust structure to minimize formal charges
Which atom is your central atom?
The one with the lowest electronegativity
Can hydrogen be a central atom?
No, because it can only form 1 bond
Draw the Lewis structure for H2O
Draw the Lewis structure for CO2
Draw the Lewis structure for XeF2
Draw the Lewis structure for NO3-
What does VSEPR stand for?
valence shell electron pair repulsion
What is VSEPR theory
Based on the idea that electron groups repel one another to achieve maximum separation.
What does AXE stand for?
A-Central atom
X-Peripheral atom
E- lone pair electrons
What is the AX2 molecular geometry?
AX2
What is the AX2 shape?
Linear
what is the AX2 bonding angle?
180
What is the molecular shape that lends to the greatest distance between electrons?
AX2
Linear structure
What is the AX3 molecular geometry?
AX3
What is the AX3 shape?
Trigonal Planar
What is the AX3 bonding angle?
120
What is the AX3 molecular geometry with a lone pair of electrons?
AX2E
What is the AX2E shape
bent
What is the AX2E bonding angle?
<120