Chemistry - Atomic Structure + Periodic Table + Bonding
What does the quantum l tell us? How does the value of n limit the value of l? hint: it's a formula
# of subshells and their shape For any given value of n, the range of possible values for l is 0 to n-1 If n = 1, l = 0 --> only one subshell with one value If n = 2, l = 0 and 1 --> only two subshells since there are 2 possible values
What is the easy formula to calculate formal charge?
# of valence electrons that element is supposed to have - (# of bonds + # of lone electrons) Example: Oxygen has 3 pairs of lone e- + 1 bond Charge: 6 - [(3)(2)+1] = 6-7 = -1
What is the Rydberg equation, which relates wavelength of light emitted to the orbital level change of an electron?
(1/λ) =R((1/nf^2) - (1/ni^2)) λ = Wavelength R = Rydberg's Constant (-1.097⋅10^7) nf = Final Orbital Level ni = Initial Orbital Level
Of the following ions, which will have the smallest radius in a mass spectrometer? (A) Carbon-12 (B) Nitrogen-14 (C) Oxygen-16 (D) Potassium-19
(A) Carbon-12 The smaller the mass, the smaller the radius of the circle.
Which type of substance will be slightly repelled by an external magnetic field? (A) Diamagnetic (B) Antiferromagnetic (C) Paramagnetic (D) Ferromagnetic
(A) Diamagnetic Diamagnetic substances will be slightly repelled by an external magnetic field. Diamagnetic substances have only paired electrons in its outermost orbital.
Na+ is an example of which type of substance? (A) Diamagnetic (B) Antiferromagnetic (C) Paramagnetic (D) Ferromagnetic
(A) Diamagnetic Na+ is an example of a diamagnetic substance because it has paired electrons in its outermost orbital.
Uranium has an atomic number of 92 and an atomic mass of 235. How many neutrons does Uranium contain? (A) 92 (B) 110 (C) 143 (D) 235
(C) 143 235 neutrons and protons - 92 protons = 143 neutrons
Which type of substance will be pulled into an external magnetic field? (A) Diamagnetic (B) Antiferromagnetic (C) Paramagnetic (D) Ferromagnetic
(C) Paramagnetic Paramagnetic substances will be pulled into an external magnetic field. Paramagnetic substances have one or more unpaired electrons.
Deuterium and Hydrogen are related in that they are: (A) Isomers (B) Isotropes (C) Isotonic compounds (D) Isotopes
(D) Isotopes Isotopes are similar in atomic number but different in terms of their atomic mass due to differing numbers of neutrons.
When electrons go from a lower energy level to a higher one, they: 1. (Absorb/Emit) light 2. (Higher/Lower) potential 3. (Closer/Farther) from nucleus
1. Absorb 2. Higher 3. Farther
1. Ionic compounds have (high/low) melting points and (high/low) boiling points. 2. Ionic compounds (do readily/do not readily) dissolve in water. 3. (Solid/Liquid) state of ionic compounds are good conductors of electricity *Hint for 3: think of the structures for each state
1. high, high - strong electrostatic force between ions 2. do readily (NaCl for example) 3. Solid - ions are split apart and have charges; in solid - lattice structure is rigid
1. Covalent compounds have (higher/lower) melting points and (higher/lower) boiling points compared to ionic compounds. 2. Covalent compounds are (poor/good) conductors of electricity) in the liquid or aqueous state.
1. lower, lower - relatively weak intermolecular interactions 2. poor - b/c they do not break into ions
What is the atomic mass (amu) defined as?
1/12 of the mass of C-12 and is approximately 1.66 x 10^-24 g; it is nearly equal to the mass number
What is the formula that describes the maximum number of electrons that can be held within a subshell?
4l + 2
A mole is equal to Avogadro's number. What is Avogadro's number equal to? (Asking for the number)
6.02 x 10^23 atoms
Which will fill first, the 5d subshell or the 6s subshell?
6s subshell has lower energy as shown with using n +l rule so it will fill first (Hund's rule) n = 5, d = l = 2 --> 5 + 2 = 7 n = 6, s = l = 0 --> 6 + 0 = 6 --> LOWER
Define coordinate covalent bond.
A covalent bond in which one atom contributes both bonding electrons. For example, Nitrogen donating its e- to Boron as a base
A covalent bond is considered non-polar if the difference between the atoms' electronegativity is __________. A) < 0.5 B) 0.5 - 1.7 C) > 1.7 D) none
A) < 0.5 0.5 - 1.7 = polar covalent > 1.7 = ionic
Which emission series corresponds to transitions from energy levels from n greater than/equal to 3 to n = 2? A) Balmer B) Lyman C) Paschen D) none
A) Balmer
Electrons closer to nucleus are at ______ levels. A) lower B) higher
A) lower
Which is the principal quantum number? A) n B) l C) m d) s
A) n
Materials composed of atoms with unpaired e- are considered: A) paramagnetic B) diamagnetic C) neither
A) paramagnetic The unpaired e- will orient their spins to align with magnetic field to form an attraction. Those with only paired e- are slightly repelled - diamagnetic Paramagnetic = PARAllel spins
What is the weighted average of the different isotopes of an element called?
Atomic weight Determined by %(atomic mass 1) + % (atomic mass 2) ...
The p orbital corresponds to l = _______ and has _____ orbitals. A) 0, 2 B) 1, 3 C) 2, 2 D) 3, 3
B) 1, 3
When dissolved in water, which of the following ions is most likely to form a complex ion with H2O? A) Na+ B) Fe2+ C) Cl- D) S 2-
B) Fe2+ Transition metals tend to form complexes due to their oxidation states
Which emission series corresponds to transitions from energy levels from n greater than/equal to 2 to n = 1? A) Balmer B) Lyman C) Paschen D) none
B) Lyman Has shorter proton wavelengths in the UV region; includes larger energy transitions
A positive E for energy difference between electrons of different states indicates: A) emission B) absorption C) neither
B) absorption This means difference of 1/nf^2 - 1/ni^2 is negative which means it must end at higher n 1/Lambda = -Rh (1/nf^2 - 1/ni^2)
Compared to the energy difference between n=3 and n=4, the energy difference between n=1 and n=2 is: A) less B) greater C) equal
B) greater The difference in energy between two shells decrease as distance from nucleus increases because energy difference is a function of 1/ni^2 - 1/nf^2
Ionic bonds create: A) individual molecular bonds B) lattice structures C) neither
B) lattice structures Ionic bonds create a lattice structure that consists of repeating rows of cations and anions to maximize attractive forces between oppositely charged ions and minimize repulsions
Which Lewis structure is more stable? A) one with negative charge on C B) one with negative charge on O
B) one with negative charge on O O is more electronegative than C and can accommodate the charge better --> more stable
If an atom absorbs a certain color, what color do we perceive? A) the absorbed color B) the complementary color C) neither - we see other colors
B) the complementary color
Although the octet rule dictates much of molecular structure, some atoms can violate the octet rule by being surrounded by more than eight electrons. Which of the following is the best explanation for why some atoms can exceed the octet.? A) Atoms that exceed the octet already have eight electrons in their outermost electron shell B) Atoms that exceed the octet only do so when bonding with transition metals C) Atoms that exceed the octet can do so because they have d-orbitals in which extra electrons can reside D) Some atoms can exceed the octet because they are highly electronegative
C) Atoms that exceed the octet can do so because they have d-orbitals in which extra electrons can reside
Which of the following types of intermolecular forces provides the most accurate explanation for why noble gases can liquefy? A) Hydrogen bonding B) Ion-dipole interactions C) Dispersion forces D) Dipole-dipole interactions
C) Dispersion forces
Which emission series corresponds to transitions from energy levels from n greater than/equal to 4 to n = 3? A) Balmer B) Lyman C) Paschen D) none
C) Paschen
Which of the following does not easily give up electrons? A) metals B) transition metals C) non-metals D) metalloids
C) non-metals --> THINK OF THE ELEMENTS ALL THE WAY ON THE RIGHT
Which of the following describes the orbital geometry of an sp3 hybridized atom? A) linear B) trigonal planar C) tetrahedral D) octahedral
C) tetrahedral Orbital geometry is also known as electron domain geometry. Hybridization is based on the number of electron domains surrounding an atom. An sp3-hybridized atom, such as C in CH4 or N in :NH3, mixes the s and p subshells (one s and three p orbitals) to form four equivalent orbitals. Four equivalent orbitals point at the vertices of a tetrahedron.
What is the MOLECULAR geometry of NH3? A) trigonal planar B) tetrahedral C) trigonal pyramidal D) bent
C) trigonal pyramidal
The 6A group contains Oxygen, Sulfur, and Selenium (Se) and the group is also known as _________. Hint: asking for the name of the group like group 7 is named halogens
Chalcogens
Which has a bigger IONIC radius Cl- or Cl? What about Mg2+ and Mg? Hint: think of Zeff and the relationship between proton and electron.
Cl- Mg Cations have smaller ionic radius than their uncharged state and reverse for anions
An electron in the shell n=4 and subshell l=2 is in A) 4n B) 4s C) 4p D) 4d
D) 4d
When electrons return to their ground state, they _____ light with a wavelength of a characteristic of the specific energy transition they undergo. These energy transitions are _______. A) absorb, quantized B) emit, continuous C) absorb, continuous D) emit, quantized
D) emit, quantized
Describe the trend for atomic radius for the periodic table across a period and down a group.
Decreases across a period b/c Zeff increases (e- more tightly bound). Increases down a group b/c more inner shells (valence e- more distant)
As the bond order increases, bond length (increases/decreases). Explain why. As bond order increases, bond energy (increases/decrease). Explain why.
Decreases because as number of shared electrons increases, the two atoms are pulled closer to each other. Increases b/c atoms are more tightly held together and closer which makes it harder to break the bonds
What is the Bohr's formula for energy of electron derived from his angular momentum formula? What does it tell us?
E = -Rh/n^2 R = 2.18 x 10^-18 J/electron; Rydberg unit of energy Energy of electron changes in discrete amounts with respect to quantum number; energy increases (becomes less negative) as n increases; negative sign represents the attraction of electron to proton in any of its quantized state
What is the formula of the energy of a quantum based on Planck relation?
E=hf h = 6.626 x 10^-34 (J)(s); Plank's constant f = frequency of radiation
What is the electrostatic attraction between the valence shell electrons and nucleus known as? Does it increase or decrease as we move from left to right within one period? Hint: it's 3 words
Effective nuclear charge - a measure of the net positive charge experienced by the outermost electrons INCREASES FOR ELEMENTS IN THE SAME PERIOD FROM LEFT TO RIGHT SINCE ATOMIC NUMBER (# OF PROTONS INCREASE)
Explain the difference between electronic geometry and molecular geometry.
Electronic: spatial arrangement of all pairs of e- around central atom (both bonding + lone pairs) Molecular: spatial arrangement OF ONLY BONDING PAIRS OF E-; # of atoms that surround and bonded to central atom (coordination #) is important for molecular geometry
What is electron affinity described as? Describe its trend across a period and down a group.
Energy dissipated by a gaseous species when it gains an electron; exothermic INCREASES across period and DECREASES down a group *NOTE: noble gases have electron affinities of 0 because they are already very stable with their octet
What is ionization energy defined as? Describe its trend across a period and down a group.
Energy required to remove an e- from a gaseous species; endothermic - requires energy Greater Zeff = electrons more tightly bound = harder to remove. Ionization energy INCREASES across period w/ greater Zeff and DECREASES down a group (due to more shielding with more shells and so valence e- not as tightly bound)
What is the equation for magnetic force in terms of magnetic field strength and velocity of an ion?
F = qvB F = Magnetic Force q = Charge of ion V = Velocity of ion B = Magnetic Field Strength
As n increases, the energy level and radius of the electron's shell decreases. True or False
False As n increases, the energy level and radius of the electron's shell INCREASES.
Which equation can be used in tandem with F = qvB in order to calculate the mass of an ion in a mass spectrometer based on the radius of the circle?
Fc = m(v^2/r)
The energy necessary to remove 1st electron is known as first ionization energy and the energy necessary to remove 2nd electron is known as second ionization energy. How do these two values usually compare?
First < Second Makes sense since removing one electron would make the rest more tightly bound to the nucleus --> harder to remove a second electron
What is the ground state of an atom? What is the excited state of an atom?
Ground state - state of lowest energy where all electrons are in the lowest possible orbitals Excited state - when at least one e- has moved to a subshell of higher than normal energy
Name the elements that are stable with incomplete octet. There are 5.
Hydrogen (2), Helium (2), Lithium (2), Beryllium (4), Boron (6)
Correctly match the following terms with their abbreviation: I. Mass number II. Atomic number III. Number of neutrons (A) A (B) M (C) N (D) Z
I. (A)II. (D)III. (C) Mass number- A Atomic number- Z Number of neutrons- N
What happens in ionic bonding? What happens in covalent bonding?
Ionic: One or more electrons from an atom with low ionization energy (metal) are transferred to an atom with high electron affinity (non-metal); electrostatic force between the opposite charges of these ions Covalent: electrons are shared between two atoms
What does the Heisenberg uncertainty principle state? Hint: it is part of the quantum mechanical model for electrons
It is impossible to simultaneously determine, with perfect accuracy, the momentum and the position of an electron
What is Bohr's formula of angular momentum of electrons? What does it tell us?
L = nh/2pi n = principal quantum number h = 6.626 x 10^-34 (J)(s); Plank's constant Only variable is principal quantum number so angular momentum of electron changes in discrete amounts with respect to n
Non-metals close to metalloid line possess a (larger/smaller) ionic radius because they require more e- than other non-metals to achieve configuration of noble gasses.
LARGER
What is the formula that describes the energy difference between electrons at two different energy levels? What does this formula tell us about the energy of the emitted photon and energy transitions of electrons.
LEFT SIDE: E = hc/lambda Rh is NEGATIVE Energy of emitted photon corresponds to difference in energy of final - initial 1/Lambda = -Rh (1/nf^2 - 1/ni^2)
What is a Lewis acid? What is a Lewis base?
Lewis acid: accept lone pair of e- Lewis base: donate lone pair of e-
List the intermolecular forces from weakest to strongest.
London dispersion, dipole-dipole, hydrogen bonding 1. London dispersion: the result of induced dipoles that shift moment to moment. 2. Dipole-dipole: polar molecules orient so that positive and negative dipoles are close to each other (attractive forces); permanent compared to London dispersion 3. Hydrogen bonding: H with N,O,F
The ability of metals can be described under two terms: malleability and ductility. Define each.
Malleability: ability of metal to be hammered into shapes Ductility: ability of metal to be pulled or drawn into wires
What is the formula that describes the maximum capacity of electrons that can be held in a shell?
Maximum number of electrons within a shell = 2n^2
What is electronegativity described as? Describe its trend across a period and down a group.
Measure of the attractive force that an atom will exert on an electron in a chemical bond; greater = attracts e- within a bond; related to ionization energy INCREASES across a period and DECREASES down a group.
According to the rules established, Chronium should have the electron configuration [Ar][4s^2][3d^4], but its configuration is actually [Ar][4s^1][3d^5]. Explain why.
Moving on electron from 4s to 3d allows 3d subshell to be half filled which is more stable. The same behavior is found for elements in the same group and for those with 3d^9 (will become 3d^10).
The ionization energy trend increases across a period and decreases down a group, but why does nitrogen have a higher ionization energy than oxygen? hint: think about the configuration and the # of electrons in orbital
N has 3 half-filled p orbitals while O has 2 half-filled p orbitals and 1 filled one so N is more stable and it's harder to remove an e- from it.
What are the three elements capable of doing hydrogen bonding?
N,O,F
If two electrons are in the same orbital, they must have the (same/opposite) spin (s number). This is because they are paired. hint: think of how we draw arrows in orbitals
OPPOSITE
Alkali and alkaline earth metals are so _______ that they are not naturally found in their neutral state and are usually in their ionic/charged state.
Reactive
Metals close to metalloid line possess a (large/smaller) ionic radius because they require more e- to be lost than other metals to achieve configuration of noble gasses.
SMALLER
When does a sigma bond form? When does a pi bond form? (In terms of orbitals)
Sigma: when orbitals overlap head to head Pi: when orbitals overlap so that there are 2 parallel e- cloud densities
What does the quantum m describe? How is it determined mathematically?
Specifies the particular orbital within a subshell; # of values of m tells us the # of orbitals in that subshell Possible values: -l to +l; # of values for m = 2l + 2
What does the quantum s tell us? What are its possible value(s)?
Spin orientation -1/2 or +1/2
Name some elements that can hold more than 8 electrons in their octet.
Sulfur (12), Phosphorus (10)
As we move across the period, protons and electrons are added. As the positivity of the nucleus increases, what happens to the electrons?
The electrons, including those in the valence, experience a stronger electrostatic pull towards center of atom. This causes the electron cloud to move closer and bind more tightly to the nucleus.
There are two resonance structures for a molecule. One has no formal charges while the other does with large charge separation. Which is a major contributor to the resonance hybrid?
The one with no formal charges b/c it's more stable
Each element has its electrons excited to a different set of distinct energy levels so each possesses a unique atomic emission spectrum that acts as a fingerprint. True or False
True
______ electrons have the strongest interactions with the surrounding environment and weakest interactions with the nucleus. They are more likely to become involved in bonds with other atoms.
Valence
What is the electron configuration of Fe3+? Electron configuration of Fe is [Ar][4s^2][3d^6] Hint: this question is testing to see if you know how to remove electrons from subshells in the right order
[Ar][3d^5] 4s has higher n so electrons will be removed from 4s first (also lower in energy) and 2 e- can be removed from 4s so last one is removed from 3d.
The number of shared electron pairs between two atoms is called the _________ _________. The ______ _______ is the average distance between the two nuclei of atoms in a bond. The ________ ________ is the energy required to break a bond by separating its components into their isolated, gaseous atomic states. Fill the above statements with: bond energy , bond order, bond length
bond order, bond length, bond energy
Name the common elements that ALWAYS abide by the octet rule.
carbon, oxygen, nitrogen, fluorine, sodium, magnesium
Positively charged ion is called _______. Negative charged ion is called ________.
cation; anion
As we move down a given group, the quantum number increases which means the valence electrons are increasingly (closer/farther) from the nucleus with more inner shells. As a result, there is a (increase/decrease) electrostatic attraction between valence and the nucleus.
farther, decrease
As we go down a given group, the (increased/decreased) shielding by the inner shell electrons cancels the increased positivity of the nucleus. What is this effect of Zeff (effective nuclear charge?)
increased Zeff stays roughly the same among elements in a given group.
Match the corresponding l number to name of subshell 1) l = 0 2) l = 1 3) l = 2 4) l = 3 A = p B = s C = d D) = f
l= 0 = s l= 1 = p l = 2 = d l= 3 = f
What are the four quantum numbers that an electron can be described with? What is their relationship with each other?
n, l, m, s Value of n limits values of l which in turn limits values of m. The values of these numbers give info about the size, shape, and orientation of the orbitals
What is the formula to calculate the dipole moment of a polar covalent bond or polar molecule?
q = magnitude of charge d = displacement vectors separating the partial charges
A/representative elements have valence electrons in orbitals of ____ or ____ subshells. B/non representative elements have valence electrons in orbitals of ______ or ______ subshells. Lanthanide and actinide series have valence electrons in orbitals of ____ or _____ subshells.
s, p s, d s, f
