chemistry-chap-4

What is the formula for the compound methane?

CH4

nonpolar covalent bond

When two bonded atoms attract electrons with equal strength,

Determine the number of bonding electrons and the number of nonbonding electrons in the structure of SCl2.

the line indicates the bond between S and Cl and each line is two bonding electrons so there are 4 bonding electrons and the remaining are non bonding electrons So there are 16 non bonding electrons so the answer is 4,16

The formal charge of an atom in a molecule can be calculated based on the following formula:

formal charge=valence e−−(nonbonding e−+bonding e−2)

How many covalent bonds does hydrogen form in electrically neutral compounds?

hydrogen forms 1 covalent bond in neutral compounds

polar covalent bond

one in which the electrons are unequally shared between the atoms.

What is the formal charge on the hydrogen atom in HBr

0

What is the formal charge on the Bromine atom in HBr

0 Because the formal charges of the individual atoms add to zero, the hydrogen bromide molecule is neutral overall. Formal charges are useful in assessing the feasibility of a bonding arrangement when more than one valid Lewis structure can be written for a molecule.

How many lone pairs are on the central atom in BCl3?

0 In neutral covalent compounds, boron typically has three bonds and no lone pairs. Therefore it has only six electrons around it (not eight), which is why it is an exception to the octet rule.

Consider the following element combinations. Classify the bonds formed between each pair as ionic, polar covalent, or nonpolar covalent based solely on each element's position on the periodic table. N-N Sr-O Rb-N O-F S-Cl Br-Br P-Cl Mn-Cl

1. nonpolar covalent -If the electronegativity difference (usually called ΔEN) is less than 0.5, then the bond is . 2. polar covalent-If the ΔEN is between 0.5 and 1.6, the bond is considered 3.ionic- If the ΔEN is greater than 2.0, then the bond is

If you include structures in which sulfur has an expanded octet and exclude structures with triple bonds, how many resonance structures can be drawn for sulfur trioxide,SO3 ?

7 At least seven valid dot structures can be drawn for this molecule. However, some of them require that sulfur have an expanded octet. Therefore, the three structures in which sulfur has exactly eight valence electrons will be the most prevalent.

Determine the number of bonding electrons and the number of nonbonding electrons in the structure of SiO2.

8 and 8

How many lone pairs are on the central atom of BrF3?

BrF3 should have 2 lone pairs (four unshared electrons total) on the central atom.In this compound, Br has a total of ten electrons around it (not eight), which is why it is an exception to the octet rule.

Consider thefollowing four molecules. Which of these satisfy the octet rule andwhich do not? PF5 CS2 BBr3 CO32-

CS2 and CO3-2 follow the octet rule.The octet rule is a chemical rule of thumb that reflects observation that atoms of main-group elements tend to combine in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas. PF5 is an exception to the octet rule and will work.CO3-2 will satisfy the rule because it hastwo extra electrons which is why the compound has a -2 charge.CS2 simply follows the rule.Phosphorus pentachloride (PCl5) and sulfur hexafluoride (SF6) are examples of molecules that deviate from the octet rule by having more than 8 electrons around the central atom.

Which is the best Lewis symbol for oxygen?

For part A the answer is D because Oxygen has 6 valence electronsand can form up to 2 bonds.

Draw the electron-dot formula for SiCl2Br2.

For the SiCl2Br2 Lewis structure, calculate the total number of valence electrons for the SiCl2Br2 molecule (SiCl2Br2 has 32 valence electrons). After determining how many valence electrons there are in SiCl2Br2, place them around the central atom to complete the octets.

For a molecule of fluorous acid, the atoms are arranged as HOFO. (Note: In this oxyacid, the placement of fluorine is an exception to the rule of putting the more electronegative atom in a terminal position.) What is the formal charge on each of the atoms? Enter the formal charges in the same order as the atoms are listed. Express your answers as charges separated by comma. For example, a positive one charge would be written as +1. Formal Charge for H, O, F, O =

H - :O: - :F: - :O:: The dash representing a bond. H has no electrons unbonded, O has 4 electrons unbonded, F has 4 electrons unbonded, and O has 6 electrons unbonded where the bond is a lone pair donated from F. Formal Charge: Number Valence electrons - Number of bonds - number of unbonded electrons H = 1 - 1 - 0 = 0 First Oxygen = 6 - 2 - 4 = 0 F = 7 - 2 - 4 = +1 Second oxygen = 6 - 1 - 0 = -1

Draw the structure of CO2,3−. Include all lone pairs of electrons and formal charges.

How to: To calculate formal charge of an atom, use the equation below. Take the valence number of the atom and subtract the number of bonds and the number of non-bonding electrons.

-yne.

Hydrocarbons with triple bonds are named basically the same, we replace the -ane ending with -yne.

The hydrogen atom is not actually electronegative enough to form bonds to xenon. Were the xenon-hydrogen bond to exist, what would be the structure of XeH4?

In this compound, Xe has a total of twelve electrons around it (not eight), which is why it is an exception to the octet rule. Hydrogen is also an exception because is it stable with only two electrons rather than eight.

What is the name for the compound IF7?

Iodine heptafluoride

What is the formula for the compound nitrogen monoxide?

NO

What is the formula for the compound tetraphosphorus decoxide?

P4O10

How many electrons should be shown in the Lewis symbol for hydrogen?

Part B there should on be one electron for hydrogen, Hydrogen onlyhas one electron

Which choice represents a pair of resonance structures? Note that lone pairs have been omitted for clarity. C=O and Cl−Cl Cl−O−H and Cl−O− O=C=O and O≡C−O O=N−F and N=O−F

Resonance increases rather than decreases stability. Think about the molecules knocking around against each other. A lone pair might be shifted from the oxygen toward the carbon, increasing the electron density on the second oxygen. The answer is O=C=O and O≡C−O

Two possible electron-dot structures are shown for the cyanate ion, NCO−. What can you conclude about how favorable the structures are?

Structure A is more favored. This is due to Formal Charges. Just remember the formula: Formal Charge = Group # - (Number of unpaired electrons + 1/2 bonded electrons) ...and that Lewis structure always favors the most neutral structure of formal charges which in this case would be(0,0,-1)

Which statement best describes an O3 molecule?

The Lewis structures in Figure 1 indicate that the ozone molecule has two equivalent resonance structures, which means the electrons are delocalized. From the Lewis structure, we see that the bond order for O2 is 2 (a double bond), whereas the bond order for O3 is 1.5 (one and a half bonds). Scientists previously believed that a molecule such as ozone switched rapidly back and forth between its different resonance forms. More recent experiments have shown that the molecule actually assumes the average of all the resonance forms, with the electrons delocalized over all three oxygen atoms as shown in the following diagram

How many resonance structures can be drawn for ozone, O3?

There are two resonance structures for O3 (ozone). - Resonance structures are necessary to show how electrons are distributed in chemical bonds in a molecule. - Remember, the molecule isn't flipping back and forth between structures! It's an average of the resonance structures.

-ene

When a hydrocarbon has a double bond we replace the -ane ending with -ene

-yl ending

When an alkane is a substituent group they are named using the -yl ending instead of the -ane ending. So, -CH3 would be a methyl group.

-ane suffix

When the molecule has just single bonds we use the -ane suffix.The simplest carbon molecules are compounds of just carbon and hydrogen, hydrocarbons. We name the compounds based on the length of the longest carbon chain. We then add prefixes and suffixes to describe the types of bonds and any add-ons the molecule has.

Which of the following is the best Lewis symbol for bromine?

answer is d Bromine has 7

Isomers

are compounds that have the same formula but different bonding.

How many covalent bonds does carbon form in neutral compounds?

carbon forms 4 covalent bonds in neutral compounds Covalent bonding involves the sharing of electrons between atoms. The number of covalent bonds an atom can form relates to the number of electrons it can share and still result in a neutral molecule. It is important to know how many bonds certain elements will form in order to draw structural formulas for molecules.

What is the name of the covalent compound CCl4?

carbon tetrachloride

What is the name of the covalent compound N2O5?

dinitrogen pentoxide

How many covalent bonds does nitrogen form in electrically neutral compounds?

nitrogen forms 3 covalent bonds in neutral compounds (has 1 lone pair)

How many covalent bonds does oxygen form in electrically neutral compounds?

oxygen forms 2 covalent bonds in neutral compounds (has 2 lone pairs) Covalent bonding involves the sharing of electrons between atoms. The number of covalent bonds an atom can form relates to the number of electrons it can share and still result in a neutral molecule. It is important to know how many bonds certain elements will form in order to draw structural formulas for molecules.

ionic bond

results when the sharing is so unequal that fully charged ions form.