Honors Chemistry: Unit 5 test

What is Li core charge

+1

What is the core charge of a Hydrogen atom?

+1 (one valence electron)

What is He core charge?

+2

What is Cl core charge

+7

What is the core charge of a fluorine atom?

+7 (7 valence electrons: look at group number, count 1,2-3,4,5,6,7)

Know the resonance structures for CO₃²⁻ and its formal charges

- charge on 2 of the Os with 6 dots -the C-O bond order is 4/3 (1.5)

What is the formal charge of the last N: HN₃? (quiz question)

-1 (5-6=-1)

How can you find valence electrons? and what are they?

-Electrons in the outermost orbital -you can find them by look at groups in the periodic table skipping the transition metals (1-7,8)

Identify two elements that can represent "X" if X has one lone pair in the molecule XBr₄?

-There are 28 total valence electrons for Br and since X has one pair of lone electrons so now the total is 34 electrons -Se, Te can work because it can hold more than 8 valence electrons

When do you not include formal charges?

-when they are all zero -or when it's neutral

What is the bond order for H₂

1 (H-H, there is one bond, and the bond energy is 436 kJ/mole)

How many valence electrons does H₂CO have?

12

How many valence electron are in F₂?

14 (7+7)

How many valence electrons does Cl₂ atom have?

14 (7+7)

The typical bond length for a C-N single bond (bond order=1) is 147 pm. Based on this result, what is the expected typical bond length for a C-O single bond (Bond order=1) (quiz question) A) 143 pm B)147 pm C) 151 pm D) 205 pm

143 pm

How many valence electrons are in HCOOH? (quiz question)

18 (2+4+12)

Hydrogen must share ___ electrons (bonding pair)

2

What is the bond order for CO₂?

2 (the bond energy is 804)

Hydrogen must share ___ ____ or a ____ _____

2 electrons, bonding pair (which is represented by a line, and no more than 1 line)

(quiz question) How many valence electrons are there in the PCl₃ molecule?

26 (5+7(3))

What is the bond order of N₂?

3 (bond energy is 945)

How many valence electrons are in C₆H₆? (quiz question)

30 (24+6)

How many valence electrons are in SO₄⁻² (quiz question)

32 (6+24+2)

How many valence electrons does SiCl₄

32 [4+7(4)=32]

How to calculate bond order if you have renocence structures? -What is Carbonate (CO₃²⁻) bond order

4/3 (represented as fraction: there are 4 bonds in one structure averaged over 3 structures)

Formal Charge of NH₄⁺?

5-4=+1 for N (So formal charge is # of valence electrons - # of valence electrons in the bonded atom, so count the lines)

How many valence electrons are in C₆H₁₂O₆? (quiz question)

72 (24+12+36)

How many valence electrons does SiH₄ molecule have?

8

How many valence electrons are in NH₄⁺ (quiz question)

8 (5+4-1)

What is the Lewis structure for HSH and HOH? Is the S-H bond weaker than the O-H bond on HOH? (quiz question)

>> H-S-H (with 2 dots above and below S) >> H-O-H (with 2 dots above and below O) >S-H is the weaker bond

____ _____ is defined as the energy required to break the the bond that holds two adjacent atoms together in a molecule

Bond energy

What elements follow the octet rule?

C, N, O, F

What is the bond order for the C-C and C-H bond of H₃CCH₃

C-C=1 C-H=1

Which bond is the shortest? (quiz question) *C-Cl *C-F *C-Br *C-I

C-F (is also the strongest bond b/c the low number of electrons which make it close to its atomic radius. This results is it being the strongest and the shortest)

Which bond is the weakest? (quiz question) *C-Cl *C-F *C-Br *C-I

C-I (is also the longest b/c the high amount of electrons make it very far away from its atomic radii, which makes it spread out and very weak)

Rank N₂, H₂, and CO₂ in increasing bond order?

H₂ CO₂ N₂

_______ _______ are based on the number of valence electrons present in each of the constituent atoms of the molecule

Lewis Structures

Bond order, bond length, and bond energy are closely related. The shorter a bond, the _____ its bond strength. A shorter bond will therefore have a higher energy than a longer bond. Bond order also plays a role. For a given pair of atoms, the higher the bond order, the shorter and ______ the bond will be.

Stronger, Stronger

True or False: The shorter the bond, the stronger the bond is

True

Write the Lewis Structure for PCl₃ (quiz question)

all follow the octet rule

Which bond is shorter, a double bond or single bond?

double bond

The ____ the bond order means the ___ it is to break

higher, harder

The ____ the bond order, the ___ bond energy is required

higher, more

Lewis Dot structure video -explanation -steps -how to figure out valence electrons -drawing structure

https://youtu.be/cIuXl7o6mAw

As bond length ____, bond energy _____.

increase, decreases

_____ are created when atoms are combined together

molecules

What is the Lewis structure for Iodine

seven dots around an I

covalent bonds

sharing of two electrons in the valence shell of both atoms

the formal charge of each atom is calculated by:

subtracting the number of valence electrons assigned to the atom from the number of valence electrons in diagram

What is the lewis structure for H₃CH? Is the C-H bond stronger than a Si-H bond

the C-H bond is stronger because it is smaller (it's above the Si)

What bond would be harder to break? one with a triple bond or one with a double bond?

triple bond