1.
What type of ion forms when an atom gains electrons?
Correct Answer
C. Negative
Explanation
When an atom gains electrons, it becomes negatively charged. This is because electrons have a negative charge, so when they are added to an atom, the overall charge of the atom becomes negative. Therefore, the correct answer is negative.
2.
What type of ion forms when an atom loses electrons?
Correct Answer
A. Positive
Explanation
When an atom loses electrons, it becomes positively charged. This is because electrons have a negative charge, so when they are lost, the atom is left with a net positive charge. Therefore, the correct answer is positive.
3.
Isotopes are atoms of the same element with the same number of protons and:
Correct Answer
A. A different number of neutrons.
Explanation
Isotopes are atoms of the same element that have the same number of protons, but a different number of neutrons. Neutrons are particles found in the nucleus of an atom, and their number can vary among isotopes of the same element. This difference in the number of neutrons gives each isotope a different atomic mass. Electrons, on the other hand, are negatively charged particles that orbit the nucleus, and their number does not affect the identity of the element. Molecules, on the other hand, are made up of multiple atoms bonded together and are not relevant to the concept of isotopes.
4.
Carbon-14 is a radioactive isotope used to determine the age of ancient objects composed of organic matter. Carbon-12 and carbon-13 are other isotopes of carbon. The number of subatomic particles varies among these carbon isotopes?
Correct Answer
B. Neutrons
Explanation
The number of subatomic particles that varies among carbon isotopes is neutrons. Carbon-14 has 8 neutrons, carbon-12 has 6 neutrons, and carbon-13 has 7 neutrons. Electrons, photons, and protons are not the subatomic particles that differ among these isotopes.
5.
Lead (Pb-208) is the heaviest stable isotope known. It has an atomic number of 82. How many neutrons does Pb-208 have?
Correct Answer
B. 126
Explanation
The atomic number of an element represents the number of protons in its nucleus. Since the atomic number of lead (Pb) is 82, it means that there are 82 protons in its nucleus. The atomic mass of an element represents the total number of protons and neutrons in its nucleus. Therefore, to find the number of neutrons in Pb-208, we subtract the atomic number from the atomic mass. In this case, 208 - 82 = 126 neutrons.
6.
The particular type of element is determined by the number of:
Correct Answer
B. Protons
Explanation
The particular type of element is determined by the number of protons. Protons are positively charged particles found in the nucleus of an atom. The number of protons in an atom is called the atomic number, and it determines the element's identity. Each element has a unique number of protons, which distinguishes it from other elements on the periodic table. Therefore, the number of protons is crucial in determining the type of element.
7.
An atom has six protons and eight neutrons. Its atomic mass is ________________ atomic mass units.
Correct Answer
E. Fourteen
Explanation
An atom with six protons and eight neutrons has an atomic mass of fourteen atomic mass units. The atomic mass is determined by the total number of protons and neutrons in the nucleus of an atom. In this case, the atom has a total of fourteen particles in its nucleus, which gives it an atomic mass of fourteen atomic mass units.
8.
Isotopes differ from each other with respect to the number of:
Correct Answer
B. Neutrons only.
Explanation
Isotopes are atoms of the same element that have a different number of neutrons. Protons determine the element's identity, while electrons determine its charge. Isotopes have the same number of protons and electrons, but their neutron count varies. Therefore, the correct answer is "neutrons only."
9.
The difference between an electrically neutral atom and an ion is that:
Correct Answer
A. An ion has an unequal number of protons and electrons, while an atom has an equal number
Explanation
An electrically neutral atom has an equal number of protons and electrons, meaning that the positive charge of the protons is balanced by the negative charge of the electrons. On the other hand, an ion has an unequal number of protons and electrons, resulting in a net positive or negative charge. This imbalance in the number of protons and electrons causes ions to have a charge, while atoms remain neutral. Therefore, the correct answer is "an ion has an unequal number of protons and electrons, while an atom has an equal number."
10.
What is the maximum number of covalent bonds that can form between a single carbon and 1 or more hydrogen atoms?
Correct Answer
D. 4
Explanation
Carbon has four valence electrons, meaning it can form four covalent bonds. Each hydrogen atom has one valence electron, so when bonding with carbon, each hydrogen atom can contribute one electron to form a covalent bond. Therefore, the maximum number of covalent bonds that can form between a single carbon and 1 or more hydrogen atoms is four.
11.
Breaking which type of bond would require the most energy?
Correct Answer
A. Covalent
Explanation
Covalent bonds are formed when two atoms share electrons. These bonds are very strong and require a significant amount of energy to break. In a covalent bond, the electrons are tightly held between the atoms, creating a strong attraction. Breaking a covalent bond would require breaking this strong attraction and overcoming the electrostatic forces holding the atoms together. Therefore, breaking a covalent bond would require the most energy compared to electrostatic, hydrogen, or intermolecular bonds.