GenChem201 Ch.1-3
What forms ionic bonds?
-*Metal and a nonmetal* -Large difference in electronegativity
What forms covalent "molecular" bonds?
-*Nonmetal and a nonmetal* -Small difference in electronegativity
Dalton's Atomic Theory
1) elements are composed of atoms. 2) atoms of same element are identical, but differ from other elements. 3) elements can mix together 4) atoms only change when mixed with other elements
What is the energy of a mole of photons that have a wavelength of 785 nm?
1.52 × 10⁵ J
Prefix - "deci" Symbol - d
10^-1
Prefix - "pico" Symbol - p
10^-12
Prefix - "femto-" Symbol - f
10^-15
Prefix - "centi" Symbol - c
10^-2
Prefix - "milli" Symbol - m
10^-3
Prefix - "micro" Symbol - μ
10^-6
Prefix - "nano-" Symbol - n
10^-9
Prefix - "deca" Symbol - da
10^1
Prefix - "tera-" Symbol - T
10^12
Prefix - "hecto-" Symbol - h
10^2
Prefix - "kilo-" Symbol - k
10^3
Prefix - "mega-" Symbol - M
10^6
Prefix - "giga-" Symbol - G
10^9
A spherical iron ball has a diameter of 11.6 cm and has a mass of 5.50 kilograms. This particular ball has a hole inside of it. Given that the density of iron metal is 7.86 g/cm³, what is the volume in cm³ of the hole inside the ball? (The volume of a sphere is (4/3)πr³.)
118 cm³
How many neutrons are in a ⁴He atom?
2
How many core electrons does an atom of beryllium (Be) contain?
2 Beryllium (Be) has four electrons and an electron configuration of 1s2 2s2. The electrons in the 1st shell are in the core and the electrons in the outer shell are valence electrons.
Determine the correct number of significant figures in the number or calculation result. 81310 - 76200 / 0.00216 =
2400000
What is the wavelength (in nm) of a photon if the energy is 7.87 × 10⁻¹⁹ J?
253 nm
An electron has the following set of quantum numbers: 3, 2, -1, -½. What is the energy level for this electron?
3 The first number listed is the energy level: nn = 3
For a hydrogen atom, calculate the wavelength of light (in m) that would be emitted for the orbital transition of n(initial) = 5 to n(final) = 4. Submit an answer to four significant figures. The Rydberg constant is 1.09678 x 10⁷ m⁻¹.
4.052 × 10⁻⁶ m
A photon has a frequency of 6.8 × 10⁸ Hz. What is the energy of this photon?
4.5 × 10⁻²⁵ J
What is the energy (in J) of a photon with a frequency of 7.13 × 10¹⁴ s⁻¹?
4.72 × 10⁻¹⁹ J
How many electrons are in a neutral carbon-14 atom?
6
Calculate the effective nuclear charge on a valence electron in an oxygen atom.
6 Oxygen has an atomic number of 8. There are 8 protons and 8 electrons in an oxygen atom. Oxygen has 6 valence electrons and 2 shielding electrons. Therefore, electrons in the valence shell will experience an effective nuclear charge of 6+ Zeff = Z − S Zeff = 8 - 2 = 6+
How many electrons can be assigned to orbitals designated by the quantum numbers n = 6, ℓ = 1?
6 The number of atomic orbitals with a given value of n is determined by the quantum number ℓ. ℓ = 1 represents the set of p orbitals, which consists of three orbitals which can each hold two electrons, meaning that the orbitals designated by the quantum numbers n = 2, ℓ = 1 (the 2p orbitals) can contain a total of 6 electrons.
Calculate the effective nuclear charge on a valence electron in a bromine atom.
7 The effective nuclear charge is the net charge that an electron experiences. An estimate of the effective nuclear charge (Zeff) can be calculated from Zeff = Z − SZeff, where Z is the atomic number and S is the number of shielding electrons. Bromine has an atomic number of 35. There are 35 protons and 35 electrons in a bromine atom. Bromine has 7 valence electrons and 28 shielding electrons. Therefore, electrons in the valence shell will experience an effective nuclear charge of 7+ Zeff = Z − S Zeff = 35 − 28 Zeff=7+
What would be the kinetic energy, in J, of an electron with a wavelength of 0.185 nm, which would be equivalent to the wavelength of electromagnetic radiation in the X-ray region? (The mass of an electron is 9.11 × 10⁻²⁸ g.)
7.04 × 10⁻¹⁸ J
In one atom, what is the maximum number of electrons that could have the quantum number of n = 2?
8 electrons When n=2, there are one 2s orbital and three 2p orbitals. There can be two electrons in each orbital. Thus, 2 × 4 orbitals = 8 electrons 2 × 4 orbitals = 8 electrons.
Determine the correct number of significant figures in the number or calculation result. 81310 − 0.00216 =
81310
Perform this mathematical operation and express the answer to the correct number of significant figures: 1.285 × 10⁻² - 1.24 × 10⁻³ A) 0.01161 B) 1.16 × 10⁻² C) 1.16 × 10² D) 1.59 × 10⁻⁵
A) 0.01161
Which of the following compounds exhibits both ionic and covalent (molecular) bonding? A) CaSO₃ B) SO₃ C) S₃Cl₂ D) CoS
A) CaSO₃
Which of the following atoms would have the longest de Broglie wavelength, if all have the same velocity? A) Li B) Na C) Fe D) Pb E) Not possible to tell with given information
A) Li
Photons are shone on a piece of metal and one electron is ejected for each absorbed photon. What happens when the wavelength of light is decreased? A) The ejected electrons would have greater kinetic energy. B) More electrons would be ejected. C) The velocity of the ejected electrons would decrease. D) The ejected electrons would have lower kinetic energy. E) No change in the ejected electrons would be observed.
A) The ejected electrons would have greater kinetic energy.
A ground state atom of Mg could not have any electrons with which of the following configurations? A) n = 3, ℓ = 1, mℓ = 0, ms = +½ B) n = 2, ℓ = 1, mℓ = 0, ms = +½ C) n = 3, ℓ = 0, mℓ = 0, ms = +½ D) n = 2, ℓ = 0, mℓ = 0, ms = +½ E) n = 1, ℓ = 0, mℓ = 0, ms = +½
A) n = 3, ℓ = 1, mℓ = 0, ms = +½ This is a 3p electron, which is not found in a Mg atom.
An electron is shown to occupy a d orbital. Which of the following sets of quantum numbers can describe this electron?
A) n = 3, ℓ = 2, mℓ = -2 A d orbital is represented by the quantum number ℓ = 2 ( s = 0, p = 1, d = 2, f = 3). The only option that meets this criterion is the set n = 3, ℓ = 2, mℓ = -2.
If ℓ = 0, which of the following may be true? A) n = 6 B) mℓ = -1 C) mℓ = 1 D) ms = 1 E) ms = 0
A) n = 6 The value for mℓmℓ must be between −ℓ and +ℓ, so if ℓ = 0, mℓ must 0 as well. The value for ms must be either +1/2 or -1/2, so it cannot be 1 or 0. The value of ℓ must be less than the value of n, so ℓ = 0 and n= 6 is acceptable.
If light has a lot of energy, it will have: A) A small frequency B) A small wavelength C) Low speed D) High speed E) A small number of photons
B) A small wavelength E=hν=hc/λ
What scientist proposed that the electron in a hydrogen atom can only have certain energies (i.e., the electron is quantized)? A) Planck B) Bohr C) Rutherford D) Rydberg E) de Broglie
B) Bohr
Determine the empirical formula for C₆H₁₄O. A) C₃H₇O B) C₆H₁₄O C) C₂H₇O D) CHO E) C₁₂H₂₈O₂
B) C₆H₁₄O
Which scientist surmised the scientific principle that the position and momentum of an electron cannot be known simultaneously with a high degree of accuracy? A) Planck B) Heisenberg C) Schrödinger D) de Broglie E) Pauli
B) Heisenberg
Halogens tend to form anions because A) losing electrons will fill their octet faster than gaining them. B) gaining electrons will fill their octet faster than losing them. C) halogen element ionization energies are lower than transition metal ionization energies. D) halogen atomic radii tend to be larger than their corresponding ionic radii. E) halogen atomic radii tend to be smaller than their corresponding ionic radii.?
B) gaining electrons will fill their octet faster than losing them.
Sodium bicarbonate (baking soda, NaHCO₃) is used to deodorize refrigerators. What kind of bonding does this compound exhibit?
Both ionic and covalent
A molecule has an empirical formula of CH, and its molar mass is known to be 26 g/mol. What is its molecular formula? A) CH B) CH₂ C) C₂H₂ D) C₂H E) C₃H₃
C) C₂H₂
Which of the following species has the same number of protons as Fe³⁺? A) Mn³⁺ B) Co²⁺ C) Fe²⁺ D) Ni⁺ E) Co³⁺
C) Fe²⁺ Ions of the same element all contain the same number of protons and only differ in their number of electrons.
Which of the following states that no two electrons can have the same set of four quantum numbers? A) Hund's rule B) de Broglie wave equation C) Pauli exclusion principle D) Bohr equation E) Schrödinger equation
C) Pauli exclusion principle
Who developed the equation that allowed the energy of the electron to be described quantum mechanically? A) Einstein B) Planck C) Schrödinger D) Heisenberg E) de Broglie
C) Schrödinger
An electron has the following set of quantum numbers: 3, 2, -1, -½. What type of orbital is represented by these quantum numbers? A) an s-orbital B) a p-orbital C) a d-orbital D) an f-orbital
C) a d-orbital A d-orbital has ℓ=2.
What is observed when a noble gas is heated and the emitted light shone through a prism? A) a solid band of color B) a solid band of color with some lines missing C) individual lines of varying colors D) red light E) blue light
C) individual lines of varying colors
Carbon dioxide is a _____ compound composed two types of _____ atoms. A) molecular; metal B) ionic; metalloid C) molecular; nonmetal D) ionic; metal
C) molecular; nonmetal
Which of the following sets of quantum numbers can describe a 3p electron? A) n = 1, ℓ = 3, mℓ = 1 B) n = 3, ℓ = 2, mℓ = 1 C) n = 3, ℓ = 1, mℓ = 1 D) n = 3 , ℓ = 0, mℓ = 1 E) n = 2, ℓ = 3, mℓ = 1
C) n = 3, ℓ = 1, mℓ = 1
Which has the larger radius, Se or Ca?
Ca
Classify each of the following compound as ionic or covalent. COF₂
Covalent
Classify each of the following compound as ionic or covalent. H₂Se
Covalent
What happens to the energy of a photon if the wavelength is doubled? A) Energy doubles B) Energy quadruples C) No change in energy D) Energy is reduced by one-half E) Energy is reduced by one-quarter
D) Energy is reduced by one-half E = hc / λ
An electron has the following set of quantum numbers: 3, 2, -1, -½. Which of the following atoms could have an electron in the ground state with these quantum numbers?
D) Kr An electron with n = 3 and ℓ=2 would be in the 3d orbital. The only atom from the list which meets this criteria is Kr.
Effective nuclear charge, Zeff, is defined as A) the number of protons minus the number of valence electrons. B) the difference in electronegativities of two bonded atoms or ions. C) the number of protons minus the number of electrons. D) the true nuclear charge minus the charge that is shielded by electrons. E) the number of protons in the nucleus.
D) the true nuclear charge minus the charge that is shielded by electrons.
For an atom of carbon, which ionization will exhibit a very large increase in the energy relative to the preceding ionization? A) 1st B) 2nd C) 3rd D) 4th E) 5th
E) 5th The fifth ionization of carbon will see a large increase in the energy required as this ionization will be removing a core electron.
Based on the positions of the following elements on the periodic table, which of them would you expect to form a 3+ cation? A) scandium B) aluminum C) phosphorus D) calcium E) Both A and B
E) Both A and B Scandium loses one 3d electron and two 4s electrons to form the Sc3+ cation. Aluminum loses one 3p electron and two 3s electrons to form the Al3+ cation.
What quantum mechanics principle states that electrons are added to atomic orbitals with the same energy so that each orbital is singularly occupied with electrons having the same spin? A) Schrödinger's equation B) Heisenberg uncertainty principle C) Pauli exclusion principle D) Aufbau principle E) Hund's rule
E) Hund's rule
The trend towards smaller atomic radii as one moves to the right in a period is _____. A) faulty, as atomic radii in a period are nearly uniform in size. B) because of electron pair repulsion causing the expansion of the orbitals. C) wrong. Atomic radii increase across a period left to right as the larger d and p orbitals are occupied after the s orbital. D) due to the effective nuclear charge decreasing. E) due to the effective nuclear charge increasing.
E) due to the effective nuclear charge increasing.
Which has a lager ionization energy, F or Cl?
F
Rank the following atoms in order of decreasing first ionization energies (i.e., highest to lowest): Li, Be, Ba, F.
F > Be > Li > Ba In general, first ionization energy decreases down a group and increases across a period.
What are the main group elements?
Groups 1, 2, 13-18 (s and p blocks)
Consider these electron transitions in a hydrogen atom: I. n = 2 → n = 1 II. n = 3 → n = 1 III. n= 1 → n = 4 Which of the electron transitions would release the most energy? A) I B) II C) III D) I, II, and III release the same amount of energy
II. n = 3 → n = 1
Classify each of the following compound as ionic or covalent. FeCl₃
Ionic
Classify each of the following compound as ionic or covalent. SrO
Ionic
What is the noble gas core in the electron configuration for Sb?
Kr
Which of the following pairs of ions represent isoelectronic species? A) Mg²⁺ and O²⁻ B) K+ and Li+ C) Ca²⁺ and F- D) Fe²⁺ and S²⁻ E) Al³⁺ and Cl⁻
Mg²⁺ and O²⁻ Both have the electron configuration of [Ne].
Ni has a higher atomic number than Co, but Co has a higher atomic mass. Co-59 has a 100% natural abundance. The 5 stable isotopes of Ni are Ni-58, Ni-60, Ni-61, Ni-62, and Ni-64. Which Ni isotope has the highest natural abundance?
Ni-58
What does the mass number of an atom represent?
Number of protons and neutrons
Rank the following atoms in order of increasing size (i.e., smallest to largest): Li, Al, Be, Ba, O.
O < Be < Li < Al < Ba
Polar vs Nonpolar Covalent Bonds
Polar: Unequal electron sharing between 2 oppositely charged ends Nonpolar: Equal electron sharing and no noticeable charge
Rank the following atoms in order of increasing first ionization energies (i.e., lowest to highest): Rb, F, Mg, B, N.
Rb < Mg < B < N < F
What is sheilding?
Sheiling is the repulsive forces exerted on valence electrons by core electrons.
Convert each of the following measurements or final calculations into grams. a. 351 kg b. 2457000 ng c. 19305 mg d. 29835000 μg
a. 3.51 × 10⁵ g b. 2.457 × 10⁻³ g c. 19305 × 10⁻³ g d. 29.835 g
What did De Broglie propose?
all objects have wavelengths related to their momentum.
Atomic Radius Trend
increases down and to the left
Electron Affinity Trend
increases up and to the right
Ionization Energy Trend
increases up and to the right
Bohr Model
model of the atom in which electrons move rapidly around the nucleus in paths called orbits
What is the fourth quantum number?
ms (+/- 1/2)
What is the third quantum number?
mℓ (-ℓ to +ℓ)
What is the principal quantum number and what does it represent?
n represents the energy level
quantum numbers
n, l, ml, ms
Pauli Exclusion Principle
no two electrons in the same atom can have the same set of four quantum numbers
transition metals valence electrons
ns (n-1) d orbital
Main group valence electrons
outer s and p electrons
Hunds Rule
states that single electrons with the same spin must occupy each equal-energy orbital before additional electrons with opposite spins can occupy the same orbitals
What is the secondary quantum number and what does it represent?
ℓ represents the orbital (n-1)
Name the ℓ values that represent each orbital?
ℓ=0 is the "s" orbital ℓ=1 is the "p" orbital ℓ=2 is the "d" orbital ℓ=3 is the "f" orbital