chem-atomunit1

Perchloric acid is a superacid used in the production of rocket fuel. If two moles of perchloric acid are mixed with four liters of water, the normality of the resulting solution will be closest to: A. 0.5 N. B. 1 N. C. 2 N. D. 4 N.

0.5 It has a formula of HClO4, making it a monoprotic acid. For this reason, its normality is the same as its molarity, or (2 moles HClO4) / (approximately 4 L total solution) = 0.5 M = 0.5 N. if it were diprotic, wouldve been 1N.

A particular element overwhelmingly prefers to form one bond and possess three lone pairs. Which group does this species likely belong in? A. Group 1 B. Group 15 C. Group 17 D. Group 18

17 Groups are columns in the periodic table, where each element in a group has the same number of valence electrons. The question stem indicates that the element in question has seven such electrons: one from the bond and six from the lone pairs. This brings to mind the halogens, all of which have seven valence electrons. These elements are found in the seventeenth column from the left of the periodic table.

z eff of Arsenic (33) w n=3 electron?

23! Z eff = Z - #e at n= sum of all the ones at and before asked in question - 1 Effective nuclear charge can be found by subtracting the total number of electrons in all shells preceding the one in question from the nuclear charge (the number of protons). Arsenic has an atomic number of 33. The atom pictured appears to be oxidized (As+), as we would expect the outermost shell to have 5 electrons if the atom were neutral. In other words, the diagram includes 32 electrons, but we only need to consider those in the first two shells. Starting from the first ring, the numbers of electrons in those shells are, respectively, 2 and 8. (Note that this information corresponds to the atom's electronic configuration.) To calculate the effective nuclear charge when n = 3, then, we only need to find (33 - 10), or 23.

which has higher energy? 4s vs 3d 4s vs 3p 2s vs 2p 3s vs 2p

3d>4s 3p>3s 3s>2p 2p>2s

Which one has less energy? 6s or 4f? where do you remove electrons from first? Also does 5D have more than 4f?

4F 6s yes

Lyman series

A set of spectral lines that appear in the UV region when a hydrogen atom undergoes a transition from energy levels n>1 to n=1.

Balmer series

A set of spectral lines that appear in the visible light region when a hydrogen atom undergoes a transition from energy levels n>2 to n=2.

Which of these options correctly lists five elements in order of decreasing reactivity with water? A. Be, Mg, Ca, K, Cs B. K, Cs, Be, Mg, Ca C. Cs, K, Ca, Mg, Be D. Cs, Be, Mg, K, Ca

Cs, K, Ca, Mg, Be Reactivity with water is heavily based on ionization energy. Specifically, elements with low IE values tend to lose electrons easily, allowing them to rapidly form oxides in water. In general, Group 1 elements are more reactive than Group 2 ones, as they lose single electrons very readily. (In fact, sodium and potassium metals are known for exploding when placed in contact with water.) Only choice C lists the five elements in question from lowest to highest ionization energy.

Perchloric Acid

HClO4 (Strong Acid)

Which of these statements accurately describe the behavior of photoelectrons?I. A photoelectron's energy can exceed that of the incident photon.II. A photoelectron's energy cannot equal the energy of the incident photon.III. The threshold frequency and the likelihood of electron ejection are proportional.IV. The intensity of incident light is unrelated to the energy of an ejected photoelectron. A. I and II only B. I and III only C. II and III only D. II and IV only

II and IV only Due to conservation of energy, the energy of a photoelectron may only be less than that of the incident photon. This concept is due to the existence of the work function, a quantity of energy required for an electron to be released at all. Since some of the incident photon's energy is devoted to overcoming this threshold, not all of it can be converted to kinetic energy for the ejected electron. For choice IV, remember that the intensity of the incident ray determines the number, not the individual energies, of the ejected photoelectrons. III: The threshold frequency is simply the frequency that must be surpassed for a photoelectron to be emitted. It is the energy of the incident photon (and whether it surpasses this threshold) that determines whether ejection occurs.

Paschen series

Infrared light produced by the hydrogen atom emission with a final state of n = 3.

Which redox reaction best represents the combination of oxygen and solid sulfur into sulfur dioxide? A. S + O2 + 2e- → SO2 + 2e- B. S + 2O + 4e- → SO2 + 4e- C. 2S + 2O2 + 2e- → 2SO2 + 2e- D. S + O2 + 4e- → SO2 + 4e-

Like other redox reactions, this can be written as two separate half-reactions and then combined. The oxidation half is S → S4+ + 4e-, while the reduction half is O2 + 4e- → 2O2-. When these reactions are put together, we get S + O2 + 4e- → SO2 + 4e-.

do transition metals form colored gases?

NAh, While transition metals are typically associated with bright colors, they do not typically enter the gas phase.

Os3+ conf?

[Xe] 4f14 5d5 so s gone, 1 d gone

0.5 moles of argon gas are being held in a balloon that also contains several moles of gaseous nitrogen. When the balloon is compressed to approximately half its volume, which of the following measurements change? A. The molarity of Ar gas B. The molality of Ar gas C. The mole fraction of Ar gas

a

Hund's rule

each orbital must contain one electron before any electrons are paired. T

he Aufbau principle states that

electrons fill orbitals in order of increasing energy. The diagram does not violate this idea.

The intensity of the incident ray determines the xxx, not the individual energies, of the ejected photoelectrons.

number of photoelectrons.

The Pauli exclusion principle states

o two electrons can have the same set of quantum numbers. no same spin

can oxygen form an oxide?

technically no