what is the atomic number of an element

ATI TEAS 7

ATI TEAS 7 science review

1. What is the atomic number of an element?

A. The number of protons in an atom's nucleus.
B. The number of neutrons in an atom's nucleus.
C. The number of electrons in an atom's valence shell.
D. The number of isotopes of an element.

Correct answer: A

Rationale: The atomic number of an element is the number of protons in an atom's nucleus. This number is crucial as it determines the element's identity and its position on the periodic table. Option B is incorrect because the number of neutrons can vary in isotopes but is not the atomic number. Option C is incorrect as the number of electrons in an atom's valence shell can vary based on the element's charge, not defining the atomic number. Option D is also incorrect because the number of isotopes is not the atomic number of an element.

2. What are the phases of bacterial growth and infection?

A. Lag, exponential, stationary, death
B. Exponential, stationary, lag, death
C. Stationary, exponential, lag, death
D. Lag, stationary, exponential, death

Correct answer: A

Rationale: The correct answer is A: Lag, exponential, stationary, death. The phases of bacterial growth start with the lag phase where bacteria acclimate to their environment, followed by the exponential phase characterized by rapid growth. This is then followed by the stationary phase where growth slows as resources deplete, and finally, the death phase where the population declines. Choice B is incorrect as it has the order of phases mixed up. Choice C is incorrect as it also has the order of phases mixed up. Choice D is incorrect as it has the stationary phase occurring before the exponential phase, which is inaccurate.

3. Elements tend to gain or lose electrons to achieve stable electron configurations like those of noble gases. Their group number often indicates the number of electrons gained/lost and the resulting ionic charge, providing a good starting point for prediction.

A. Ionic bonds involve electron sharing, while metallic bonds involve electron transfer.
B. Ionic bonds are weak and directional, while metallic bonds are strong and non-directional.
C. Ionic bonds exist between metals and non-metals, while metallic bonds exist only between metals.
D. Ionic bonds form discrete molecules, while metallic bonds form extended structures.

Correct answer: C

Rationale: Ionic bonds typically form between metals and non-metals, where one atom donates electrons (cation) and the other accepts electrons (anion). This results in the transfer of electrons. Metallic bonds, on the other hand, occur between metal atoms where electrons are shared among a sea of delocalized electrons, leading to the characteristic properties of metals like malleability and conductivity. Choice A is incorrect because ionic bonds involve electron transfer, not sharing. Choice B is incorrect as ionic bonds are strong, not weak, and are non-directional, while metallic bonds are strong and non-directional. Choice D is incorrect as ionic bonds do not form discrete molecules but rather a lattice structure, whereas metallic bonds form extended structures.

4. Which of the following bones is part of the axial skeleton?

A. Femur
B. Humerus
C. Skull
D. Pelvis

Correct answer: C

Rationale: The correct answer is C: Skull. The axial skeleton consists of bones along the body's central axis, including the skull, vertebral column, ribs, and sternum. Choices A, B, and D are incorrect because the femur, humerus, and pelvis are part of the appendicular skeleton, which comprises the bones of the limbs and girdles.

5. What is the process by which a cell divides into two or more new cells?

A. Mitosis
B. Meiosis
C. Both mitosis and meiosis
D. None of the above

Correct answer: A

Rationale: Mitosis is the process by which a cell divides into two identical daughter cells. This type of cell division is essential for growth, repair, and maintenance of multicellular organisms. Meiosis, on the other hand, is a type of cell division that produces gametes (sperm and egg cells) with half the number of chromosomes as the parent cell. Meiosis does not directly result in the formation of new cells, as it is specifically geared towards the production of reproductive cells. Therefore, the correct answer is A. Option C, stating both mitosis and meiosis, is incorrect because meiosis is not involved in the general process of cell division to produce new cells; it is specialized for gamete formation. Option D is incorrect because mitosis is indeed the process responsible for cell division in which one cell divides into two daughter cells, making it the accurate choice for this question.