CHM151 Exam 1

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?

(0.2200×126amu)+(0.3400×128amu)+(0.4400×130amu) =128.44amu

Which quantum state (n,ℓ,mℓ) is NOT possible? A) (2,0,0) B) (3,1,-1) C) (3,0,1) D) (3,2,2) E) (16,15,14)

(3,0,1) The value for mℓ must be between -ℓ and ℓ, so if ℓ = 0, mℓ must 0 as well. As such, the quantum state (n = 3, ℓ = 0, mℓ = 1) is not possible.

You measured the mass of a dry powder on a balance to be 23.76 g. What would you report as the uncertainty of this measurement?

0.01

Determine the mass, in grams, of 0.550 moles of Co (1 mol of Co has a mass of 58.93 g).

0.550 mol Co/1 x 58.93g Co/1 mol =32.4g Co

What is the energy, in J, of light that must be absorbed by a hydrogen atom to transition an electron from n = 3 to n = 6? Submit an answer to three signficant figures.

1.82 × 10⁻¹⁹ J ΔEi→f= (2.18×10^−18 J)(1/nf^2 - 1/ni^2) ΔE3→6= (2.18×10^−18 J)(1/6^2 - 1/3^2) =−1.82×10^−19 J =1.82 x 10 ^-19 J

How many milliliters are in a liter?

1000mL

When an electron in excited energy level drops to a lower energy level, a photon is emitted. If the electron is dropping to n=1, which transition will emit the longest wavelength? n=______ to n=1.

2 The transition from n=2 to n=1 will be the lowest energy (longest wavelength) transition.

How many protons are in an atom of Co?

27

Determine the mass in grams of 3.00 × 10²¹ atoms of arsenic. (The mass of one mole of arsenic is 74.92 g.)

3.00×10^21 atoms of As/1 x 1 mol/6.022×10^23 atoms of As x 74.92g As/ 1 mol As =0.373 g As

Which of the following quantities is equivalent to 3.7 cm? A) 3.7×10⁻³ m B) 3.7×10⁻⁵ km C) 3.7×10⁻² mm D) 3.7×10⁵ μm E) 3.7×10² mm

3.7×10⁻⁵ km

What is the mass in grams of 36.70 moles of KBr?

36.70 mol KBr/1 x 119.00 g KBr/ 1 mol KBr =4367 g KBr

Which of the following orbitals cannot exist? A) 2p B) 3d C) 4d D) 3f E) 162p

3f Atomic orbitals are described by their principal quantum number (n) followed by a letter that corresponds to the value for the angular momentum quantum number (ℓ), which corresponds to the following values: s = 0, p = 1, d = 2, f = 3. According to the rules governing acceptable quantum numbers, the value for ℓ can only be as high as n-1. Based on these rules, the 3f orbital (n = 3, ℓ = 3) cannot exist.

For which atomic orbital does n = 3 and ℓ = 1? A) 2s B) 3s C) 3p D) 3d E) 4d

3p Atomic orbitals are described by their principal quantum number (n) followed by a letter that corresponds to the value for the angular momentum quantum number (ℓ). Here, n = 3, so the atomic orbital symbol will begin with 3. The quantum number ℓ = 1 (s = 0, p = 1, d = 2, f = 3), which corresponds to p. Therefore, this is a 3p atomic orbital.

Determine the formula weight of Ca(NO₃)₂. Provide an answer to two decimal places.

40.08amu+(2×(14.01amu+(3×16.00amu)) =164.10amu

There are two naturally occurring isotopes of europium, ¹⁵¹Eu (151.0 amu) and ¹⁵³Eu (153.0 amu). If the atomic mass of Eu is 151.96, what is the approximate natural abundance of ¹⁵¹Eu?

50% The atomic mass is an average that represents the abundance of each isotope. The average number of these two isotopes is 152.0 amu if they are equally abundant.

An atom of the isotope ¹³³Cs contains how many protons (p), neutrons (n), and electrons (e)?

55 p, 78 n, 55 e 133=55+x x= 78

What is the mass number for an atom of barium containing 56 protons and 82 neutrons?

56+82 =138

Determine the number of atoms of C in 30.0 grams of C₁₂H₂₂O₁₁

6.33 × 10²³ atoms 30.0g/1 x 1mol/342.30 g C12H22O11 x 12 mol C/1 mol C12H22O11 x 6.022×1023 atoms C/ 1 C atom = 6.33×10^23 atoms C

What quantity in moles of CsI are in 62.0 grams of CsI?

62.0 g CsI/1 x 1 mol CsI/ 259.81 g CsI =0.239 mol CsI

What is the mass number of zinc-65?

65

What is the mass number of germanium-74?

74

The number 875000 written in scientific notation would be

8.5 x 10^5

Which color (frequency) of light travels the fastest in a vacuum?

All have the same speed The speed of light is constant in a vacuum and all colors of light travel the same speed.

Which postulate(s) of Dalton's atomic theory of matter is/are NOT true? A) Atoms of a given element are identical B) Atoms are indestructible C) Atoms combine in simple ratios to form compounds D) Both (A) and (B)

Both (A) and (B)

temp conversion C

C = 5/9 (F - 32)

What is the wavelength (in nm) of a photon if the energy is 7.26 × 10⁻¹⁹ J? (h = 6.626 × 10⁻³⁴ J • s)

E=hc/λ 7.26×10−19J = (6.626×10−34J⋅s)(3.00×108m/s)/ λ λ = 2.74×10−7m Convert m to nm 2.74×10^−7m × (1×10^9nm / 1m ) =274nm

What is the energy (in J) of a mole of photons that have a wavelength of 701 nm? (h = 6.626 × 10⁻³⁴ J • s and c = 3.00 × 10⁸ m/s)

E=hc/λ convert the wavelength from nm to m, and then plug it into this equation λ=701 nm x 1m/10^9 nm = 7.01×10^−7 m E=hc/λ E = (6.626×10^−34 J⋅s)(3.00×108m/s)/ 7.01×10^−7 m = 2.83×10^−19 J This is the energy of one photon; to determine the energy of a mole of photons with this wavelength, multiply the energy by Avogadro's number: (2.83×10^−19 J)(6.022x10^23 mol^-1) = 1.70x10^5 J/mol

What is the energy of a photon with a frequency of 7.00 × 10¹⁴ s⁻¹? (h = 6.626 × 10⁻³⁴ J • s)

E=hν Plug in the given values for frequency and Planck's constant and solve for energy. E=(6.626×10−34J⋅s)(7.00×1014 1/s) E=4.64×10^−19

Cathode rays are composed of what fundamental particle?

Electrons

What happens to the energy of a photon if the wavelength is doubled?

Energy is reduced by one-half The energy (E) of a photon of light is proportional to its frequency (ν) or the inverse of its wavelength (λ) multiplied by Planck's constant (h): E=hν=hc/λ

The accepted value for the density of iron is 7.9 g/mL. Which of the following sets of experimental data for the density of iron is the most precise? A) Group 1: 7.98 g/mL, 7.85 g/mL B) Group 2: 7.65 g/mL, 7.64 g/mL C) Group 3: 7.03 g/mL, 8.54 g/mL D) Group 4: 5.43 g/mL, 5.47 g/mL

Group 2: 7.65 g/mL, 7.64 g/mL

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?

Hund's rule

Which of the following is an example of an extensive property of copper nugget? (does depend on the amount of substance present) A) It is copper colored. B) It has a density of 8.96 g/cm³. C) It has a melting point of 1085 °C. D) It has a mass of 52.3 g.

It has a mass of 52.3 g.

Which one of the following is an example of a heterogeneous mixture? Apple juice, tap water, Italian dressing, air

Italian dressing

temp conversion K

K = C + 273.15

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

Li For different particles moving at the same speed, the particle with the smallest mass will have the longest wavelength. The de Broglie equation treats moving particles like waves, and states that the wavelength (λ) of these particles is inversely proportional to their momentum, or the product of their mass (m) and velocity (v). λ = h/mv

h

Planck's constant

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

Radio waves Energy is directly related to the frequency and inversely related to wavelength. Since radio waves have the lowest frequency and longest wavelength, they have the lowest energy.

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

Ru (100 - 56 = 44)

Which is not one of Dalton's hypotheses of atomic theory? A) Elements are composed of atoms. B) Compounds are composed of atoms of more than one element. C) A chemical reaction involves the rearrangement of atoms. D) All atoms of a given element are identical. E) The atoms of one element are the same as atoms of another element.

The atoms of one element are the same as atoms of another element.

Which of the following is an example of an intensive property of a bar gold? (does not depend on the amount of substance measured) A) The bar has a density of 19.2 g/mL. B) The mass of the bar is 11.4 kg. C) The volume of the bar is 218 L. D) The bar contains 3.49 × 10²⁵ atoms.

The bar has a density of 19.2 g/mL.

The Millikan oil drop experiment determined:

The charge of the electron

The cathode ray tube experiment determined:

The existence of electrons

The atomic mass of germanium (Ge) on the periodic table is 72.630 amu. Which of the following best explains why the atomic mass is a fraction between 72 and 73? A) The presence of different isotopes B) The presence of different isomers. C) The formation of different ions. D) The presence of different allotropes. E) The presence of different amounts of protons.

The presence of different isotopes

What is the frequency of green light that has a wavelength of 531 nm? (c = 3.00 x 10⁸ m/s)

The speed of a wave (c) is the product of its frequency (ν) and wavelength (λ). c=νλ λ=531nm x 1m/10^9nm =5.31 x 10 ^-7m ν=c/λ v=(3.00 x 10^8 m/s)/(5.31 x 10^-7m) v=5.65×10^14 s−1

An unknown element X has the following isotopes: ²⁵X (80.50% abundant, mass = 25.03 amu) and ²⁷X (19.50% abundant, mass = 26.98 amu). What is the average atomic mass of X in amu?

average atomic mass=(0.8050×25.03)+(0.1950x26.98) (20.15) + (5.261) =25.41 amu

Which of the following is a pure substance that can be broken down into simpler substances by chemical means? A) element B) homogeneous mixture C) solution D) compound E) heterogeneous mixture

compound

Which of the following is a chemical change? A) cooking an egg B) mixing oil and water C) tearing a piece of paper D) watching a DVD

cooking an egg

Energy of a photon is ______ proportional to frequency, and _______ proportional to wavelength.

directly, inversely

Density is defined as mass _____________ volume.

divided by

Which one of the following is NOT an example of a physical change? A) distilling water to remove impurities B) filtration of sand out of water C) mixing water and sugar D) electrolysis of water to form hydrogen and oxygen gas.

electrolysis of water to form hydrogen and oxygen gas.

Calcium is an example of a(n)

element

E

energy

principal quantum number (n)

energy level (n=1,2,3,4,5,6,7,8,9,10)

v

frequency

Which of the following forms of radiation has the highest frequency?

gamma rays The electromagnetic spectrum ranges from radiation with the highest frequency (shortest wavelength) to lowest frequency (longest wavelength). Of the various types of radiation, gamma rays have the highest frequency.

Which of the following forms of radiation has the shortest wavelength?

gamma rays The electromagnetic spectrum shows that gamma rays have the smallest wavelength.

In the Bohr model of the hydrogen atom, the energy required to excite an electron from n = 2 to n = 3 is _______________ the energy required to excite an electron from n = 3 to n = 4?

greater than ΔEi→f = R(1/nf^2 - 1/ni^2)

Which of the following terms describes what a doctor forms when treating patients prior to ordering medical tests?

hypothesis

What is observed when a noble gas is heated and the emitted light shone through a prism?

individual lines of varying colors Heating a noble gas promotes its electrons to excited energy states, which then relax to emit discrete wavelengths of light. When shone through a prism, this results in individual lines of varying colors.

Which of the following metric prefixes corresponds to 10³?

kilo

angular momentum quantum number

l, shape/subshell of orbital s=0 (sphere) p=1 (dumbbell) d=2 (flower) f=3 (crazy)

Red light has a _____ frequency and a _____ wavelength than ultraviolet rays.

lower, longer As can be seen on the electromagnetic spectrum, red light (and all visible light) has a lower frequency, and therefore a longer wavelength, than ultraviolet rays.

Which of the following metric prefixes corresponds to 10⁶?

mega

What is the name of the SI unit for length?

meter

Which of the following metric prefixes corresponds to 10⁻⁶?

micro

Which of the following metric prefixes corresponds to 10⁻³?

milli

Some liquid in a jar can be separated by physical means into two separate liquids, which can then be separated no further. The liquid is a(n):

mixture

magnetic quantum number

ml, orientation (direction) of orbital ex: l=2, ml ranges from -2, -1, 0, 1, 2

A theory is another word for a(n) _________.

model

which of the following is not a part of the scientific method: making observations, formulating hypotheses, modifying laws, performing experiments?

modifying laws

Rutherford's gold foil experiment determined that

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

spin projection quantum number

ms, spin direction of e- +1/2 spin up, -1/2 spin down

Which of the following sets of quantum numbers is not allowed? A) n = 3, ℓ = 2, mℓ = -2 B) n = 4, ℓ = 3, mℓ = -3 C) n = 2, ℓ = 1, mℓ =-1 D) n = 2.5, ℓ = 0, mℓ = 0 E) n = 3, ℓ = 2, mℓ = -1

n = 2.5, ℓ = 0, mℓ = 0

A single electron in an orbital has quantum numbers n = 3, ℓ = 0, mℓ = 0, ms =-½. What are the quantum numbers for the next electron added to this orbital? A) n = 3, ℓ =1, mℓ = 0, ms = +½ B) n = 3, ℓ = 0, mℓ = 0, ms = -½ C) n = 3, ℓ = 1, mℓ = 0, ms = -½ D) n = 3, ℓ = 0, mℓ = 0, ms = +½ E) n = 3, ℓ = 1, mℓ = 1, ms = +½

n = 3, ℓ = 0, mℓ = 0, ms = +½ Because there is already one electron in this orbital, the next electron added will also be added to this orbital, since this is the lowest-energy unfilled orbital (following the Aufbau principle). The Pauli exclusion principle indicates that the next electron must have a unique set of four quantum numbers, meaning the only quantum number that can be different for an additional electron in the same orbital is the ms number. The only possible values for ms are +½ and -½; since the other electron in this orbital has ms = -½, the next electron will have the set of quantum numbers given by n = 3, ℓ = 0, mℓ = 0, ms = +½.

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

n = 4, ℓ = 0, mℓ = -1 According to the rules governing acceptable quantum numbers, the value for mℓ must be between -ℓ and ℓ, so if ℓ = 0, the only possible value for mℓ is 0. Therefore, the set {n = 4, ℓ = 0, mℓ = -1} is not allowed.

Which of the following sets of quantum numbers can describe a 4s electron? A) n = 4, ℓ = 0, mℓ = 0 B) n = 3, ℓ = 0, mℓ = 0 C) n = 3, ℓ = 2, mℓ = 0 D) n = 4, ℓ = 1, mℓ = 0 E) n = 3, ℓ = 1, mℓ = 0

n = 4, ℓ = 0, mℓ = 0

A ground state atom of As could not have any electrons with which of the following configurations? A) n = 3, ℓ = 1, mℓ = 0, ms = +½ B) n = 4, ℓ = 2, mℓ = 0, ms = +½ C) n = 4, ℓ = 0, mℓ = 0, ms = +½ D) n = 3, ℓ = 2, mℓ = 0, ms = +½ E) n = 4, ℓ = 1, mℓ = 0, ms = +½

n = 4, ℓ = 2, mℓ = 0, ms = +½ A ground state As atom has the electronic structure 1s²2s²2p⁶3s²3p⁶4s²3dⁱ⁰4p³. The highest-energy orbital in this atom is 4p, which represents the quantum numbers n = 4, ℓ = 1. Of the options given, the set of quantum numbers with n = 4, ℓ = 2 is higher in energy than the highest occupied atomic orbital, so a ground state atom of As could not have any electrons with the set of quantum numbers n = 4, ℓ = 2, mℓ = 0, ms = +½.

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

n=6 The value for mℓ 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.

The nucleus of an atom contains:

protons and neutrons

If light has a lot of energy, it will have:

small wavelength

Which of the following states of matter is pictured below?

solid

A homogeneous mixture is also called a ____________.

solution

c

speed of light

Which of the following is a physical change? A) rusting of a nail B) tearing a piece of paper C) cooking an egg D) burning wood

tearing a piece of paper

which has a greater magnitude of charge? proton or electron

they have equal charges (+1 and -1)

What does the mass number of an atom represent?

total number of protons and neutrons in the atom

True or false: two electrons can simultaneously occupy the same (n,ℓ,mℓ) orbital.

true The Pauli exclusion principle states that no two electrons in a given atom can share the same set of four quantum numbers (n, ℓ, mℓ, ms). Two electrons may share the first three quantum numbers (n, ℓ, mℓ) as long as their ms (spin) quantum numbers are not the same, so this statement is true.

Which one of the following is an example of a compound? Air, water, steel, iron

water

Light wave A has a greater frequency than light wave B. Which has a greater wavelength?

wave B Wavelength and frequency are inversely related, so the light wave with the lower frequency has the greatest wavelength

λ

wavelength

Which of the following pairs represent isotopes? A) ²⁸Si and ²⁸Si⁴⁺ B) ²⁸Si and ²⁸Al C) ²⁸Si and ²⁹Si D) ²⁸Si and ²⁸Si⁴⁻ E) ²⁸Si⁴⁺ and ²⁸Al³⁺

²⁸Si and ²⁹Si

What is the wavelength of light (in nm) emitted when an electron transitions from n = 5 to n = 2 in a hydrogen atom?

ΔEi→f= (2.18×10^−18 J)(1/nf^2 - 1/ni^2) ΔE5→2= (2.18×10^−18 J)(1/2^2 - 1/5^2) = 4.58×10^−19 J The energy released by this transition is converted to a photon with energy E, which is equal to the product of Planck's constant (h) and the speed of light (c) divided by the wavelength (λ): λ = hc/E λ = (6.626×10−34 J⋅s)(3.00×108m/s)/4.58×10^−19 J = 4.34×10−7 m x 10^9nm/1m =434nm

Which of the following is true concerning ψ²? A) ψ² describes the probability of finding an electron in space. B) ψ² describes the exact path of electron motion in an orbital. C) ψ² describes the electronic structure of the atom according to the Bohr model. D) ψ² describes the exact volume of an atom. E) ψ² describes the size of an atom.

ψ² describes the probability of finding an electron in space.

Which of the following atoms has the same number of neutrons as ⁵⁹Ni?

⁶⁰Cu 59Ni has a mass number of 59. The mass number of an atom is representative of the number of protons and neutrons. Nickel has an atomic number of 28, which indicates that it contains 28 protons and 31 neutrons. 59 = 28 + x = x = 31 60Cu has a mass number of 60 and an atomic number of 29. It also has 31 neutrons. 60 = 29 + x = x = 31