Chemistry Pop Quiz - Extra Credit

Explanation
The correct answer is 50. The number 87 represents the atomic mass of Rb-87, which is the sum of the number of protons and neutrons in the nucleus. Since the atomic number of Rb (Rubidium) is 37, it means that there are 37 protons in the nucleus. To find the number of neutrons, subtract the atomic number from the atomic mass: 87 - 37 = 50. Therefore, the total number of neutrons in Rb-87 is 50.

Explanation
The Lewis model shows the bonding relationship between elements. It is based on the concept of valence electrons and uses Lewis structures to represent the arrangement of electrons in a molecule or ion. This model helps in understanding how elements form chemical bonds by sharing or transferring electrons to achieve a stable electron configuration.

Explanation
The correct answer is "directly proportional." In the electromagnetic spectrum, frequency and energy are directly proportional. This means that as the frequency of an electromagnetic wave increases, so does its energy. Similarly, as the frequency decreases, the energy of the wave also decreases. This relationship is described by the equation E = hf, where E is the energy, h is Planck's constant, and f is the frequency.

Explanation
Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. Therefore, they have the same number of electrons and the same chemical properties because the number of electrons determines an atom's chemical behavior. Additionally, since they have the same number of protons, they have the same atomic number. However, they have different atomic mass numbers due to the varying number of neutrons. The statement about the same nuclear properties is not necessarily true as isotopes can have different nuclear properties depending on the number of neutrons.

Explanation
Ca represents an alkaline earth metal. Alkaline earth metals are found in Group 2 of the periodic table and include elements such as beryllium, magnesium, calcium, strontium, barium, and radium. Ca is the chemical symbol for calcium, which is an alkaline earth metal.

Explanation
Noble gases have eight valence electrons in their outermost shell. Valence electrons are the electrons in the outermost shell of an atom and determine the chemical properties of an element. Noble gases, such as helium, neon, and argon, have a full outer shell with eight electrons, which makes them stable and unreactive. This stability is due to the fact that they have achieved the electron configuration of the nearest noble gas, which is highly favorable. Therefore, noble gases have eight valence electrons in their outermost shell.

Explanation
The average atomic mass for Cl can be calculated by multiplying the percent abundance of each isotope by its atomic mass, and then summing up these values. For the first isotope, 75.53% of Cl-35 with an atomic mass of 34.969 amu gives a contribution of (0.7553 * 34.969) amu. For the second isotope, 24.47% of Cl with an atomic mass of 3.966 amu gives a contribution of (0.2447 * 3.966) amu. Adding these contributions together gives the average atomic mass for Cl as 35.46 amu.

Explanation
Electrons carry a negative charge. They are subatomic particles that orbit the nucleus of an atom and are involved in chemical reactions and the flow of electricity. Neutrons have no charge, while protons carry a positive charge. Therefore, the correct answer is electrons.

Explanation
The wavelength of an electromagnetic wave is inversely proportional to its frequency. As the frequency increases, the wavelength decreases. In this question, the given frequency is 5.0 x 10^8 Hz. Since the frequency is relatively high, we can expect the wavelength to be relatively low. The wavelength can be calculated using the formula: wavelength = speed of light / frequency. However, since the speed of light is not given, we can use the fact that the speed of light is approximately 3 x 10^8 m/s. Plugging in the values, we get wavelength = (3 x 10^8 m/s) / (5.0 x 10^8 Hz) = 0.6 m. Therefore, the correct answer is 0.6.