Chemistry HESI A2 Quizlet

Correct Answer: C

Rationale: The columns of the periodic table are called "Groups" because elements within the same group share similar chemical properties due to having the same number of valence electrons. Each group is designated by a number and a letter, indicating the number of valence electrons. Periods refer to the rows of the periodic table, representing the number of electron shells an element has. Families is a more colloquial term used to describe groups of elements with similar properties. Rows refer to the horizontal rows of the periodic table. Therefore, the correct answer is C as it specifically refers to the vertical columns in the periodic table that share similar chemical properties.

Correct Answer: B

Rationale: The mass number represents the total number of protons and neutrons in an atom's nucleus. The atomic number represents the number of protons. By subtracting the atomic number from the mass number, we are left with the number of neutrons. Therefore, the correct answer is B: Number of neutrons. Summary: A: Number of electrons - Incorrect, as the mass number minus the atomic number does not give the number of electrons. C: Number of protons - Incorrect, as the atomic number itself represents the number of protons. D: Number of isotopes - Incorrect, as isotopes refer to atoms of the same element with different numbers of neutrons, not the result of mass number minus atomic number.

Correct Answer: B

Rationale: The correct answer is B (2). In a double covalent bond, two electron pairs are shared between two atoms. This is achieved by the sharing of two pairs of electrons, resulting in a total of four electrons being shared. However, since each pair consists of two electrons, the number of electron pairs shared to form a double covalent bond is 2. Choices A, C, and D are incorrect because a double bond involves the sharing of 2 electron pairs, not 1, 3, or 4 pairs.

Correct Answer: C

Rationale: The correct answer is C: Combustion. Combustion is a chemical reaction where a compound reacts with oxygen to produce heat, light, and often carbon dioxide and water. In this type of reaction, oxygen is a reactant and typically a hydrocarbon or organic compound is the fuel. Decomposition involves a compound breaking down into simpler substances, synthesis is when two or more substances combine to form a more complex compound, and single replacement is when one element replaces another in a compound. Combustion specifically involves the reaction with oxygen, making it the correct choice in this scenario.

Correct Answer: A

Rationale: The correct answer is A: 1. In a single bond, only one pair of electrons is shared between two atoms, resulting in a stable bond. This shared pair of electrons creates a strong attraction between the atoms, holding them together. The other choices (B, C, D) are incorrect as they represent the number of pairs of electrons shared in double, triple, or quadruple bonds, respectively, which involve 2, 3, or 4 pairs of electrons being shared, not in a single bond. Thus, the correct answer is A because a single bond involves only one pair of shared electrons.