CHEM13

What is the density of the lead brick if it has a mass of 12.4 kg and measures 5.20 cm x 10.8 cm x 19.5 cm?

11.3

The ground state electron configuration of a Se atom is

1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁴

What is the energy (in J) of a mole of photons that have a wavelength of 531 nm? (h = 6.626 × 10⁻³⁴ J • s and c = 3.00 × 10⁸ m/s)

2.25 × 10⁵ J

Determine the number of valence electrons in SO₃ and then draw the corresponding Lewis structure (with minimized formal charges).

24

What is the wavelength (in nm) of a photon if the energy is 7.69 × 10⁻¹⁹ J? (h = 6.626 × 10⁻³⁴ J • s)

258 nm

Determine the number of valence electrons in (CH₃C(O)CN) and then draw the corresponding Lewis structure.

26

How many atoms are in 3.2 pg of Ca? The molar mass of Ca is 40.08 g/mol.

4.8 × 10¹⁰

What is the atomic number for an element whose mass number is 92, which contains 50 neutrons per atom?

42

An unknown element is a mixture of isotopes ¹²⁰X and ¹²²X. The average atomic mass of X is 120.92 amu. What is the percent abundance of ¹²²X?

46.0 %

Which of the following atoms is paramagnetic? A) Al B) Ba C) Kr D) Zn E) Xe

A) Al

Which of these molecules have delocalized electrons? A) CO₃²⁻ B) CO₂ C) NF₃ D) CH₄

A) CO₃²⁻ has delocalized electrons

A more electronegative atom A) will have more attraction to the electrons in a chemical bond. B) is more likely to lose an electron. C) is less likely to form a chemical bond. D) is more likely to form an ionic bond with another highly electronegative atom.

A) will have more attraction to the electrons in a chemical bond.

Which of the following pairs of ions represent isoelectronic species?

Al³⁺ and O²⁻

What is the formula of a compound containing Al³⁺ and S²⁻ ions?

Al₂S₃

Which of the following sets of quantum numbers is not allowed? A) n = 1, ℓ = 0, mℓ = 0 B) n = 4, ℓ = 0, mℓ = -1 C) n = 3, ℓ = 1, mℓ = 0 D) n = 2, ℓ = 0, mℓ = 0 E) n = 3, ℓ = 2, mℓ = -2

B) n = 4, ℓ = 0, mℓ = -1 If l is 0 then ml must be 0 too.

What is the correct formula for barium phosphate?

Ba₃(PO₄)₂

Write the chemical formula for dichlorine heptoxide

Cl₂O₇

Rank the following atoms in order of decreasing first ionization energies (i.e., highest to lowest): Li, Be, Ba, F.

F > Be > Li > Ba

What type of light on the electromagnetic spectrum has the highest energy per photon?

Gamma waves

Neutral atoms of all isotopes of a given element have the same

Number of electrons*Isotopes are forms of the same element that differ in the number of neutrons but contain the same number of protons and electrons.

Rank the following atoms in order of decreasing size (i.e., largest to smallest): Rb, F, Mg, B, N.

Rb > Mg > B > N > F

Which element with a mass number of 100 has 56 neutrons in its nucleus

Ruthenium (Ru)*The mass number of an atom is representative of the number of protons and neutrons. Calculate the number of protons from the mass number and neutrons.100 = x + 5644 =xThen, find the element in the periodic table that contains 44 protons. The number of protons is indicated by the atomic number. The element is Ruthenium (Ru).

Predict the chemical formula for the ionic compound formed by the elements Sr and Cl

SrCl₂

A Lewis structure for XeO₃ is shown below, however, its formal charges are not minimized. Starting from this structure, complete the correct structure with minimized formal charges.

XeO₃

Draw the Lewis structure for sulfite (SO₃²⁻) with minimized formal charges. Does this molecule exhibit resonance?

Yes

What is the electron configuration of Zn²⁺? Use the core configuration.

[Ar]3d¹⁰

Which of the following is the electron configuration for Mn?

[Ar]4s²3d⁵

What is the correct IUPAC name for CaBr₂ · 6H₂O?

calcium bromide hexahydrate

What is the correct IUPAC name for As₂S₅?

diarsenic pentasulfide

What is the correct IUPAC name for Fe(NO₂)₂?

iron(II) nitrite

Rutherford's gold foil experiment determined that

most of the space in an atom is empty except for a concentrated area called the nucleus.

What is the correct IUPAC name for Sn(ClO)₄?

tin(IV) hypochlorite

Which of the following would be an isotope of ¹⁴N?

¹⁶N*Isotopes are forms of the same element that differ in the number of neutrons but contain the same number of protons and electrons. ¹⁶N is an isotope of ¹⁴N.

A metal alloy of unknown composition was bombarded with 204 nm photons to determine its photoelectric properties. Electrons photo-ejected from this alloy had a velocity of 6.40 × 10⁵ m/s. What is the wavelength (in meters) of the ejected electrons? (1 eV = 1.60 × 10⁻¹⁹ J, the mass of an electron is 9.109 x 10⁻³¹ kg, and Planck's constant is 6.626 x 10⁻³⁴ Js.)

1.14 × 10⁻⁹ m

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) = 3. Submit an answer to four significant figures. The Rydberg constant is 1.09678 x 10⁷ m⁻¹.

1.282 × 10⁻⁶ m

A pycnometer is a glass flask with a tight fitting glass stopper that is used to obtain the volume of a liquid with high accuracy. A pycnometer has a mass of 25.151 grams when empty, and a mass of 42.481 grams when completely filled with water. The pycnometer has a mass of 48.129 when completely filled with an unknown liquid. What is the density in g/cm³ of the unknown liquid? Assume the density of water is 1.000 g/cm³.

1.326 g/cm³

An unknown element X has the following isotopes: ¹²⁶X (22.00% abundant), ¹²⁸X (34.00% abundant), ¹³⁰X (44.00% abundant). What is the average atomic mass in amu of X?

128.44 amu

A metal alloy of unknown composition was bombarded with 204 nm photons to determine its photoelectric properties. Electrons photo-ejected from this alloy had a velocity of 6.20 × 10⁵ m/s. What is the work function, Φ, of this alloy in eV? (1 eV = 1.60 × 10⁻¹⁹ J, the mass of an electron is 9.109 x 10⁻³¹ kg, and Planck's constant is 6.626 x 10⁻³⁴ Js.)

5.00 eV

Calculate the frequency in hertz of electromagnetic radiation that has a wavelength of 536.0 nm. (c = 3.00 X 10⁸ m/s)

5.60 × 10¹⁴ s⁻¹ Solution: The speed of a wave (c) is the product of its frequency (v) and wavelength (^). c = v^