The Covalent Model (HL IB Chemistry)

Which of the following statements about 2-methylpropan-2-ol, CH₃C(CH₃)(OH)CH₃, are correct ? 

1. The structure contains 16 bonding pair of electrons
2. The O-C-C bond angle is 109.5 ^o
3. The total number of valence electrons is 32

Which of the following molecules has the biggest overall dipole?

 The electronegativity of four elements are given below 

N = 3.0       H = 2.1       F = 4.0      P = 2.1      

 What is the correct order of polarity for the following compounds

Below are four molecules. Which is the most polar molecule present?

The correct order of increasing boiling points for the following compounds is

What is the strongest type of intermolecular force exhibited in the amino acid molecule serine?

Hexane, C₆H₁₄ and 2,2-dimethylbutane, CH₃C(CH₃)₂CH₂CH₃, are two isomers of one another and have the same M_r of 86.0. 

Hexane has a higher boiling point than 2,2-dimethylbutane. 

Which of the following statements is not correct?

Which of the following statements about propanal and propanone are correct?

1. The strongest type of intermolecular force in both molecules is hydrogen bonding
2. The strongest type of intermolecular force in both molecules is permanent dipole permanent dipole forces
3. Both compounds are soluble in water

Which molecule has the lowest boiling point?

Which of the following statements about ammonia, NH₃, is not correct?

The following equation shows the dissociation equilibrium of PCl₅. 

PCl₅(g) → PCl₃(g)  ＋ Cl₂(g) 

The percentage yield of PCl₃ varies with temperature. 

At 160°C PCl₃ yield is 13% and at 300°C yield is100%. 

Which of the following rows is correct?

Boron trifluoride, BF₃, reacts with trimethylamine, (CH₃)₃N, to form a compound of formula (CH₃)₃N.BF₃. 

How may this reaction be written using 3D structures to show  the shapes of the reactants and products?

Which of the following statements about graphite are correct? 

1.    The carbon atoms are joined together by three covalent bonds
2.    Graphite contains delocalised electrons
3.    The C-C-C bond angle is 109.5^o

Which statement below shows the correct information about diamond and silicon?

How many lone pairs of electrons are there around the chlorine atom in a molecule of chlorine trifluoride, ClF₃?

Which one of these species has a bond angle of 120°?

Which of the following statements about silicon dioxide is correct? 

1.    Silicon dioxide forms a giant covalent network
2.    Each silicon atom is covalently bonded to four oxygen atoms
3.    Silicon dioxide molecules are V-shaped

Ibuprofen is an anti-inflammatory drug that is used for treating pain, fever and inflammation. The structure is shown below. 

Ibuprofen

 What are the correct bond angles for a and b?

Which of the following molecules obeys the octet rule?

Which row in the table is correct?

Dichlorodifluoromethane, CCl₂F₂, has been used in aerosol propellants and as a refrigerant.

Which statement helps to explain why dichlorodifluoromethane is chemically inert?

Which of the following statements are true for XeO₃?

Which species breaks the octet rule?

Which molecule is trigonal bipyramidal in shape?

How many sigma (σ) and pi (π) bonds are there in the following molecule?

Which combination correctly describes the geometry of BrF₄^- ?

Which species contain delocalised electrons?

Which combination describes the PH₄⁺ ion?

What is the hybridisation of carbon and oxygen in methanol?

Which species have delocalised π electrons? 

1.   CH₃COCH₃
2.   NO₂^-
3.   CO₃^2-

CHCl₃ and Br₂ are both liquids at room temperature due to the existence of dipoles.

What dipoles are involved within CHCl₃ and Br₂?

What is the correct structure of the chlorite ion, ClO₂^- ?

Which of the following statements about 2-chloropropene, CH₂C(Cl)CH₃ is correct?

Which of the following structures do not obey the octet rule?

1. BeCl₂
2. BF₃
3. H₂O

Which is the shortest bond length in the following gases?

Which statement best describes the intramolecular bonding in a carbonate ion, CO₃^2-?

The number of electrons in the valence shell of elements X and Y are 5 and 7 respectively. What is the formula and type of compound formed from these elements?

The nitrate(V) ion, NO₃^-, is a polyatomic ion, bonded by covalent bonds.

Which of the following shows the correct displayed formula for the nitrate ion?

In which series of compounds does covalent character increase when going from left to right?

Which of the following molecules will have the highest boiling point?

What is the correct order of boiling points for the following molecules, from lowest to highest?

In which of the following processes do hydrogen bonds get broken?

Hydrogen bonding occurs between molecules of propanal, CH₃CH₂CHO, and molecules of liquid Y. Which of the following is most likely to be liquid Y?

The following statements are all correct. Which of the statements can be explained, in part, by hydrogen bonding?

1. Ice is less dense than water
2. Butanone has a lower boiling point than butan-1-ol
3. At room temperature butanone can mix with water

Hydrogen bonding can occur between propanal, CH₃CH₂CHO and which other molecule?

Which of the following about dimethylamine, NH(CH₃)₂ , is correct?

Which of the following statements are correct? 

1. The strongest type of intermolecular force between BF₃ molecules are permanent dipole permanent dipole forces
2. The strongest type of intermolecular force between HCN molecules are permanent dipole permanent dipole forces
3. The bond angle in HCN is larger than the bond angle in BF₃

Which of the species shown below does not have resonance structures?

The correct molecular geometry and domain geometry for phosphorus trichloride, PCl₃, is:

Below are statements about the structure and bonding in silicon dioxide. Which pair of statements is correct?

Which compounds have an ionic lattice structure in the solid state?

1.   silicon dioxide
2.   sodium iodide
3.   ammonium sulfate

What is the correct shape of a ClF₂^- ion?

The correct shape and bond angle for the TlBr₃^2- ion?

Which of the following is correct for the molecules of BeCl₂ and BeCl₄^2-?

Tramadol is an example of a painkiller which is classed as an opioid analgesic. It binds to opioid receptors in the central nervous system and inhibits noradrenaline and serotonin reuptake inhibiting pain transmission 

The structure is shown below 

Which of the following are the correct bond angles for a, b and c?

Some properties of substance X are given in the following table 

What is a possible identity of substance X?

Sulfur forms the compound S₄N₄ with nitrogen, the structure is shown below.

  Which of the following statements about S₄N₄ is correct?

Nitrous acid is produced when nitrogen dioxide dissolves in water to produce acid rain. What is the correct Lewis structure for nitrous acid?

The structure of benzoic acid is shown below:

What is the correct number of sigma (σ) bonds and pi (π) electrons in benzoic acid?

Which of the following correctly describes the F-S-F bond angles in sulfur tetrafluoride, SF₄?

Which of the following species is polar?

What are the formal charges on the atoms labelled 1, 2 and 3 on the hydrogen phosphate ion, HPO₄^2-?

The structure of the DNA base cytosine is shown below:

What is the correct number of sp³ and sp² orbitals in a cytosine molecule?

Which species can be represented with only one Lewis structure?

In which group do both compounds contain delocalised electrons?

Which is not a correct statement about sp³ hybridised carbons?

The structure of the painkiller paracetamol, often known as acetaminophen, is shown below:

Which of the following is not present in the structure?

The structure of benzene is often shown as

This is a representation of a resonance hybrid structure that lies between these two possible structures

Evidence for this resonance structure is:

1. The carbon-carbon bond lengths lie between the value for a single and a double bond
2. The bond angles are all equal in benzene
3. The enthalpy of hydrogenation of benzene is less exothermic than expected

Which row of the table is correct about the trend and explanation in the boiling points of the alcohols CH₃OH, C₂H₅OH and C₃H₇OH?