Organic Chemistry I-2 Flashcards
Which of the following molecules has a net dipole moment of zero?
- CH4
- CO2
- BH3
- All of them
All of them
Here all the 3 molecules have symmetrical shapes and the central atoms are bonded with same atoms. So, the dipole moments cancel out each other resulting in no net dipole moment.
True or False: Constitutional isomers are different molecules having the same molecular formula.
True
Explanation: Constitutional isomers, also called structural isomers, have the same number and types of atoms (same molecular formula) but differ in how those atoms are connected within the molecule, leading to different structures.
True or False: Resonance structures have the same placement of atoms but different arrangement of electrons.
True
Resonance structures have the same placement of atoms but differ in the arrangement of electrons, specifically the distribution of electrons in bonds and lone pairs.
This allows for the depiction of molecules where the electron distribution cannot be represented by a single Lewis structure.
True or false: Electronegativity decreases across a row of the periodic table.
False
On the periodic table, electronegativity generally increases as you move from left to right across a period and decreases as you move down a group.
True or False: Covalent bonds result from the transfer of electrons from one element to another.
False
Explanation:
Covalent bond: When two atoms share electrons to achieve a stable electron configuration.
Ionic bond: When one atom completely transfers electrons to another, creating oppositely charged ions that attract each other.
Which of the following statements about electronegativity and the periodic table is true?
Electronegativity decreases across a row of the periodic table.
Electronegativity increases down a column of the periodic table.
Electronegativity increases across a row of the periodic table.
Electronegativity does not change down a column of the periodic table.
Electronegativity increases across a row of the periodic table.
Which of the following statements about valence electrons is true?
They are the most tightly held electrons.
They do not participate in chemical reactions.
They are the outermost electrons.
They reveal the period number of a second-row element.
They are the outermost electrons.
Explanation: Valence electrons are located in the outermost energy level of an atom. This makes them the most accessible to other atoms when forming chemical bonds. They are responsible for an atom’s reactivity and chemical behavior.
What is the molecular geometry around the boron atom in BH3?
Tetrahedral
Trigonal Planar
Trigonal Pyramidal
Linear
Trigonal Planar
Explanation: Boron has three valence electrons, which it uses to form single bonds with three hydrogen atoms, resulting in a symmetrical planar arrangement with bond angles of approximately 120 degrees.
Consider compounds which contain both a heteroatom and a double bond. For which compound is no additional Lewis structure possible?
Compound III
Which of the following is the appropriate conversion of (CH3)2CHCH2CHClCH3 to a skeletal structure?
(II)
Which of the following pair does not represent resonance structures?
III
What 2 things will change between two resonance structures?
The position of multiple bonds and non-bonded electrons.
Which of the following molecules has a net dipole moment of zero?
II the net dipole moment is zero.
What is the hybridization for each of the indicated atoms in the following compound?
I = sp2; II = sp2; III = sp3.
Explanation :
Hybridization (H) = Number of electrons domains around atom (i.e. No. of bond pairs + No.of lone pairs , including multiple bond as a single bond).
If H = 2 , then Hybridization = sp
If H = 3 , then Hybridization = sp2
If H = 4 , then Hybridization = sp3
Which of the following Lewis structures is correct?
Lewis’s structures II and III are correct.
Which of the following Lewis structures is correct?
IV
Consider compounds which contain both a heteroatom and a double bond. For which compound is no additional Lewis structure possible?
III
Which of the following molecules contain both covalent and ionic bonds?
II, IV
In conclusion, among the molecules listed, Ammonium hydroxide and Magnesium carbonate are the two compounds that contain both covalent and ionic bonds.
Follow the curved arrows to draw the second resonance structure for the ion below.
III
