2.5-2.7 Quiz

Question 1

What elements may have less than an octet in a Lewis diagram?

Answer 1

H, Be, and B

Question 2

What elements may have an expanded octet in a Lewis diagram?

Answer 2

Any nonmetal in periods 3 or greater, as a central atom only.

Question 3

Meaning of the HONC acronym and how to use it

Answer 3

Full acronym is HONC-1234
H- hydrogen(1)
O- oxygen(2)
N- nitrogen(3)
C- carbon(4)
The numbers associated with each one is how many bonds that those elements need to make. So ensure that your Lewis diagram is correct by using HONC-1234

Question 4

What element is typically in the middle of a Lewis diagram?

Answer 4

The least electronegative

Question 5

Practice drawing Lewis diagrams

Answer 5

2.5 in chapter 2 packet

Question 6

What is a rule with halogens and Lewis diagrams?

Answer 6

Never double bond halogens

Question 7

Why do bonds end up sharing electrons?

Answer 7

Because they do not have enough to complete their octet so they bond with another element to get a full valence shell(8 valence electrons)
Ex: H and C; Carbon has 4 valence electrons and they all need someone to pair up with so their compound is CH4 because every valence electron needs to make a bond to get to that full octet.

Question 8

How can you confirm that a double bond(or more) has formed?

Answer 8

Through bond energy
Ex: F2 has a bond energy of around 155, but O2 has a bond energy of around 495 because it created a double bond and that bond is harder to break which causes its increase in bond energy

Question 9

How does the number of valence electrons change if you have a -1 charge? a +1 charge?

Answer 9

You add an electron; You subtract an electron

Question 10

What is different about Lewis diagrams for ions?

Answer 10

They have brackets around them and their charge written on the outside

Question 11

Formal charge equation

How do you check that your formal charge calculation is accurate?

Answer 11

(# valence electrons)- (# lone electrons(count each dot as one) + # bonds connected(one dash counts as 1))

The sum of the formal charges of each atom should add up to zero for a molecule or add up to the charge for a polyatomic ion.

Question 12

What is the point of formal charge? How do you know which structure is most valid?

Answer 12

It helps you decide which structure is most valid. The most valid structure will have formal charges closest to zero for all atoms(best structure will have no formal charge(aka zero)). Also, negative formal charges will be placed on the most electronegative atom.

Question 13

How do you draw resonance structures?

Answer 13

Draw the possible structures with brackets around them and arrows between them

Question 14

Bond order equation

Answer 14

of bonds/ Total bonding domains

Question 15

What is the rule of thumb when drawing resonance structures with elements capable of expanded octets?

Answer 15

Try to follow the rule of octet and only use the expanded octet if it reduces formal charge

Question 16

If you were to perform the reaction: KCl yields K+ Cl would energy be released?

Answer 16

No, the separation of ions requires energy

Question 17

Ionizing an H2 molecule to H2+ changes the strength of the bond. Based on the description of covalent bonding given previously, do you expect the H—H bond in H2+ to be weaker or stronger than the H—H bond in H2?

Answer 17

Weaker, because a H—H covalent bond in H2+ has one less electron than in H2.

Question 18

Suppose a Lewis structure for a neutral fluorine-containing molecule results in a formal charge of +1 on the fluorine atom. What conclusion would you draw?

Answer 18

There must be a better Lewis structure, since F is the most electronegative element and it should carry a negative formal charge.

Question 19

Why do we draw resonance structures?

Answer 19

To show all possible structures and that the real structure is an average of all of those possibilities

Question 20

How do you draw a resonance hybrid structure?

Answer 20

You draw one structure instead of all of the possibilities and you draw a dotted line instead of a full line on all of the outside elements. With the hybrid structure you use bond order.
Ex: CO3 2-; you draw a dotted line to each oxygen instead of drawing three different resonance structures where a different oxygen has a double bond. Bond order will show that this polyatomic ion has a bond order of 1 1/3

Question 21

Practice drawing resonance structures

Answer 21

Chapter 2 packet- 2.6
2.6 daily video 1

Question 22

VSEPR Theory

Answer 22

It uses the Coulombic repulsion between electrons as a basis for predicting the arrangement of electron pairs around a central atom

Question 23

Hybridization/ hybrid atomic orbital

Answer 23

Used to describe the arrangement of electrons around a central atom

Question 24

Hybridization of molecule with bond angles around 180 degrees

Answer 24

sp

Question 25

Hybridization of molecule with bond angles around 120 degrees

Answer 25

sp^2

Question 26

Hybridization of molecule with bond angles around 109.5 degrees

Answer 26

sp^3

Question 27

How is the shape or geometry determined?

Answer 27

By the lone pairs and bonds on its central atoms because these areas will minimize electron-electron repulsion by positioning themselves as far apart as possible. Lone pairs of electrons repel more than bonds and tend to compress the angles between bonding atoms.

Question 28

How do you determine the molecular geometry if there is more than one central atom?

Answer 28

If there is more than one central atom we determine the geometric shape of each central atom individually
by following the normal steps for each central atom.

Question 29

Molecular vs Electron Geometries

Answer 29

Molecular geometry goes into more detail and includes options for lone pairs but electron geometry is more basic and just goes over number of bonding domains

Question 30

Molecular, Electron Geometry, and Bond Angle of 2 bonds and 0 lone pairs

Answer 30

Linear; 180

Question 31

Molecular and Electron Geometry and Bond Angle of 3 bonds and 0 lone pairs

Answer 31

Trigonal Planar; 120

Question 32

Molecular and Electron Geometry and Bond Angle of 2 bonds and 1 lone pairs

Answer 32

Bent; trigonal planar; <120

Question 33

Molecular and Electron Geometry and Bond Angle of 4 bonds and 0 lone pairs

Answer 33

Tetrahedral; 109.5

Question 34

Molecular and Electron Geometry and Bond Angle of 3 bonds and 1 lone pairs

Answer 34

Trigonal pyramidal; tetrahedral; <109.5

Question 35

Molecular and Electron Geometry and Bond Angle of 2 bonds and 2 lone pairs

Answer 35

Bent; tetrahedral; <109.5

Question 36

Molecular and Electron Geometry and Bond Angle of 5 bonds and 0 lone pairs

Answer 36

Trigonal bipyramidal; 90 and 120

Question 37

Molecular and Electron Geometry and Bond Angle of 4 bonds and 1 lone pairs

Answer 37

Seesaw; trigonal bipyramidal; <90 and <120

Question 38

Molecular and Electron Geometry and Bond Angle of 3 bonds and 2 lone pairs

Answer 38

T- shaped; trigonal bipyramidal; <90

Question 39

Molecular and Electron Geometry and Bond Angle of 2 bonds and 3 lone pairs

Answer 39

Linear; trigonal bipyramidal; 180

Question 40

Molecular and Electron Geometry and Bond Angle of 6 bonds and 0 lone pairs

Answer 40

octahedral; 90

Question 41

Molecular and Electron Geometry and Bond Angle of 5 bonds and 1 lone pairs

Answer 41

square pyramidal; octahedral; <90

Question 42

Molecular and Electron Geometry and Bond Angle of 4 bonds and 2 lone pairs

Answer 42

Square planar; octahedral; 90

Question 43

Sigma bonds

Answer 43

Very strong bonds that are seen as single bonds

Question 44

Pi bonds

Answer 44

It pulls the atoms closer together. There is:
One in a double bond
Two in a triple bond

Question 45

In sigma and pi, what are double and triple bonds made up of?

Answer 45

Double- 1 sigma and 1 pi
Triple- 1 sigma and 2 pi

Question 46

What happens to bonds as the number of bonds between two atoms increases?

Answer 46

The bond increases in strength and energy but decreases in length. Triple bonds are the strongest and shortest bonds. While single bonds are the weakest and longest bonds.

Question 47

Bond order

Answer 47

Number of bonds between two atoms

Question 48

Explain how bond order works.

Answer 48

For a molecule that exhibits resonance, we see that the bonds that have resonance are experimentally determined to be the same length. In ozone, O3, we would expect the single bond to be shorter than the double bond, but that is not the case. They both have a bond length that is halfway between a single and double bond, so the bond order is halfway between a single and double bond order, and its bond order is 1.5. Another way to think about this is that there are three bonds shared between two atoms, and 3/2 = 1.5.

Question 49

How to determine the polarity of a molecule?

Answer 49

If it only has nonpolar bonds in it, then it will definitely be nonpolar.
If symmetrically placed atoms surround it then it is nonpolar even if those bonds are polar.(linear, trigonal planar, tetrahedral, trigonal bipyramidal, square planar, octahedral)
If the molecule has an asymmetrical shape then it is polar.