| Atoms with the same number of protons but different numbers of neutrons are called __________. | isotopes |
| What isotope of chlorine has the same number of neutrons as Argon-38?
A) 17 Cl, B) 35 Cl, C) 36 Cl, D)37 Cl, E) 38 Cl | D |
| Which of the following elements does this electronic configuration represent?
1s2 2s2 2p5
F C N Al O | F |
| How many unpaired electrons are present in the isolated carbon atom (atomic number = 6)?
none, one, two, three, four | two |
| Which of the following is the electronic configuration of the element Fe? | 1s2 2s2 2p6 3s2 3p6 4s2 3d6 |
| Ar, K+, Cl- are isoelectronic elements (elements with the same number of electrons). What orbital does the last electron occupy? | 3p orbital |
| The atomic number of boron is 5. The correct electronic configuration of boron is: | 1s2 2s2 2p1 |
| Which of the following statements correctly describes the third electron shell that surrounds the nucleus of an atom? | The maximum number of electrons that can occupy the third shell is 18. |
| Which of the following describes a hydride ion? | a negatively charged hydrogen ion containing a pair of electrons |
| Rank the following atoms in increasing electronegativity.
N, Na, Si, O , C | Na, Si, C, N, O |
| Using the symbol δ+ and δ-, indicate the direction of the polarity in the indicated bond. | down below
δ- δ+
..
CH3O--H
.. |
| Covalent bonds may be polar or nonpolar. What property of the atoms forming a given bond determines this? | electronegativity |
| The compound methylamine, H3C-NH2, contains a C-N bond. In this bond, which of the following best describes the charge on the nitrogen atom? | slightly negative |
| Which of the compounds below bond predominantly via ionic bonding? | KCl |
| What type of bonding is most important in CH3CH2CH2CH2CH2CH3? | covalent |
| Which of the following contain(s) polar covalent bonds? | NH3 |
| What is the name given for a species that contains a positively charged carbon atom? | carbocation |
| Which of the following is the most likely (i.e. most stable) electronic structure for C2H2? | here |
| Which of the following structures, including formal charges, is correct for diazomethane, H2CN2? | here on first N +
Second N - |
| What are the formal charges on nitrogen and the starred oxygen atom in the following molecule? | N= +1, O = 0 |
| The formal charge on nitrogen in the compound below is __________. | +1 |
| Draw condensed structures for the four compounds with formula C3H9N. | CH3CH2CH2NH2
CH3CH2NHCH3
(CH3)2CHNH2
(CH3)3N |
| How many distinct p orbitals exist in the second electron shell? | 3 |
| Both sigma (σ) and pi (π) bonds can be formed by overlapping p orbitals. Describe the difference. | Sigma bonds are formed from the overlap of atomic orbitals along a circular axis of symmetrical nature, i.e., head-on overlap. All single bonds are sigma bonds.
Pi bonds are formed from the overlap of atomic orbitals along a non-symmetrical (parallel) axis, i.e., side-to-side overlap. Double and triple bonds are pi bonds. |
| Choose the correct hybridization for the atom indicated in the molecule below.
CH3CH2CH2CH3 | sp3 |
| What orbitals are used to form the covalent bonds in butane (CH3CH2CH2CH3)? | The carbon-carbon σ bonds are formed by the overlap of two carbon sp3 hybrid atomic orbitals. The carbon-hydrogen σ bonds are formed by the overlap of a carbon sp3 hybrid atomic orbital and a hydrogen s orbital. |
| Which of the following is a nonpolar molecule? | H2 |
| Which of the following is a correct formula for a compound? | CH3CH(CH3)CH2CH3 |
| How many electrons are involved in a carbon-carbon double bond? | 4 |
| Which of the following describes a triple bond? | one sigma bond and two pi bonds |
| Which carbon(s) in the following molecule is (are) sp hybridized? | carbon 4, 5 |
| What is the predicted shape, bond angle, and hybridization for +CH3? | trigonal planar, 120°, sp2 |
| What orbitals overlap to create the H-C bond in CH3+? | s-sp2 |
| The lone-pair electrons of the methyl anion occupy a __________ orbital | sp3 |
| Explain why the water molecule has a bent shape and a bond angle less than 109.5°. | The electron replusion between the two lone pairs of electrons on the oxygen of water causes the O-H bonds to squeeze close together. |
| Which of the following is closest to the C-O-C bond angle in CH3-O-CH3? | 109.5° |
| triethylamine [(CH3CH2)3N] is a molecule in which the nitrogen atom is __________ hybridized and the CNC bond angle is __________. | sp3; <109.5° |
| The N-H bond in the ammonium ion, NH4+, is formed by the overlap of what two orbitals? | sp3-s |
| Among the hydrogen halides, the strongest bond is found in __________ and the longest bond is found in __________. | HF; HI |
| The carbon- carbon double bond in ethene is __________ and __________ than the carbon-carbon triple bond in ethyne. | weaker; longer |
| Draw the structure of a molecule which contains only carbon and hydrogen atoms (only three of which are carbon) and in which two of the carbons are sp2 hybridized and the other is sp hybridized. | H2CCCH2 |
| Why is the C H bond in ethene (H2CCH2) shorter and stronger than the C H bond in ethane(H3C-CH3)? | The length and strength of a C H bond depends on the hybridization of the carbon atom. The more s character in the hybrid orbital used by carbon to form the bond, the shorter and stronger the bond. This is because an s orbital is closer to the nucleus than is a p orbital. Ethene uses carbon sp2 hybridized orbitals (1/3 s character) to make its carbon-hydrogen bonds while ethane uses carbon sp3 (1/4 s character) orbitals. |
