HESI A2
Chemistry HESI A2 Quizlet
1. What charge do Group VIA elements typically have?
- A. -1
- B. -2
- C. -3
- D. 0
Correct answer: B
Rationale: Group VIA elements, also known as Group 16 elements, typically have a charge of -2. This is because they have 6 valence electrons and tend to gain 2 electrons to achieve a stable octet configuration, resulting in a -2 charge. Choice A (-1) is incorrect as Group VIA elements need to gain 2 electrons for stability, not just 1. Choice C (-3) is incorrect because Group VIA elements do not need to gain 3 electrons to achieve stability. Choice D (0) is incorrect as Group VIA elements need to gain electrons to reach a stable configuration, resulting in a negative charge.
2. Which of the following elements is the most electronegative?
- A. Oxygen
- B. Fluorine
- C. Nitrogen
- D. Sodium
Correct answer: B
Rationale: Fluorine is the most electronegative element on the periodic table. It has the highest electronegativity value, indicating its strong ability to attract electrons in a chemical bond. This property makes it highly reactive, explaining why it is the correct answer in this question. Oxygen and Nitrogen are also electronegative elements, but they are not as electronegative as Fluorine. Sodium, on the other hand, is not electronegative; it is an electropositive element.
3. Which of the following is the weakest intermolecular force?
- A. Dipole interactions
- B. Hydrogen bonding
- C. Van der Waals forces
- D. Dispersion forces
Correct answer: D
Rationale: Dispersion forces, also known as London dispersion forces, are the weakest intermolecular forces. They are temporary attractive forces that occur due to momentary shifts in electron distribution within molecules. While dipole interactions, hydrogen bonding, and Van der Waals forces are stronger intermolecular forces, dispersion forces are the weakest because they arise from short-lived fluctuations in electron density. Dipole interactions involve permanent dipoles in molecules, making them stronger than dispersion forces. Hydrogen bonding is stronger than dipole interactions and involves hydrogen atoms bonded to highly electronegative atoms. Van der Waals forces encompass dipole-dipole interactions and dispersion forces, making them stronger than dispersion forces alone.
4. Which gas is produced when an acid reacts with a carbonate?
- A. Carbon dioxide
- B. Oxygen
- C. Hydrogen
- D. Nitrogen
Correct answer: A
Rationale: When an acid reacts with a carbonate, the chemical reaction typically yields carbon dioxide gas. Carbon dioxide is formed due to the chemical reaction between the acid and the carbonate, releasing this gas as a product. Therefore, the correct answer is 'Carbon dioxide.' Choices B, C, and D are incorrect as oxygen, hydrogen, and nitrogen are not the gases produced in this specific acid-carbonate reaction.
5. What term refers to the average of the masses of each of its isotopes as they occur in nature?
- A. Atomic number
- B. Mass number
- C. Atomic mass
- D. Neutron number
Correct answer: C
Rationale: The correct answer is atomic mass. Atomic mass is the weighted average of the masses of an element's isotopes. It takes into account the abundance of each isotope in nature to provide a more accurate representation of the element's overall mass. Choice A, atomic number, represents the number of protons in an atom. Choice B, mass number, refers to the total number of protons and neutrons in an atom's nucleus. Choice D, neutron number, specifically focuses on the count of neutrons in an atom's nucleus. These choices do not directly relate to the average mass of isotopes as asked in the question.
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