Question

Which of the following statements is incorrect? a. Isotopes have the same atomic number and different mass numbers. b. Atoms have about the same number of electrons as protons. c. All ions are atoms. d. Free radicals are dangerous because they emit energy.

Short answer

Statements c and d are incorrect.

Step-by-step solution

Evaluate statement a

Statement a says that isotopes have the same atomic number and different mass numbers. This statement is true, as isotopes of an element have the same number of protons but differ in their number of neutrons.

Evaluate statement b

Statement b asserts that atoms have about the same number of electrons as protons. This is generally true for neutral atoms, where the number of electrons equals the number of protons.

Evaluate statement c

Statement c claims that all ions are atoms. This statement is incorrect because ions are atoms or molecules that have gained or lost one or more electrons, becoming charged. Not all ions are atomic in nature; some may be molecular.

Evaluate statement d

Statement d suggests that free radicals are dangerous because they emit energy. This is incorrect; free radicals are primarily dangerous because they have unpaired electrons, which makes them highly reactive and able to cause damage to cells and DNA, not because they emit energy.

Key concepts

Atomic Number

The atomic number is a fundamental property of an element. It represents the number of protons in the nucleus of an atom. Every element is defined by its unique atomic number.
For example, hydrogen has an atomic number of 1, meaning it has one proton in its nucleus. Similarly, helium, with an atomic number of 2, has two protons.

• An element's atomic number is crucial as it determines the element's position on the periodic table and its chemical behavior.
• Isotopes of an element have the same atomic number but vary in their mass number due to differences in the number of neutrons.

Understanding the atomic number helps us identify the element and predict its interactions with other elements.

Mass Number

Mass number is another essential concept in understanding atoms. It is the sum of protons and neutrons in the nucleus of an atom.
While the atomic number is consistent across all isotopes of an element, the mass number can vary. For example, carbon has several isotopes, like carbon-12 and carbon-14, where both share the same atomic number (6) but differ in mass numbers (12 and 14, respectively).

• The mass number is not typically listed on the periodic table, but it is crucial when studying isotopes and nuclear reactions.
• The differing mass numbers provide insights into the stability and abundance of an isotope.

Mass number gives us a comprehensive understanding of an atom's composition.

Free Radicals

Free radicals are atoms or molecules that have an unpaired electron, making them highly reactive. Their reactivity can cause them to engage in unwanted chemical reactions within cells.
Free radicals can be generated through metabolic processes or external factors, such as radiation and pollution.

• This unpaired electron means free radicals are always looking to "pair up," which often results in damaging cells and DNA.
• The damage they cause is linked to aging, inflammation, and various diseases, making them a topic of study in medical fields.

Understanding free radicals is crucial in the study of biochemistry and health sciences.

Ions

Ions are charged particles that form when atoms or molecules gain or lose electrons. This process changes the balance between protons and electrons, resulting in a net charge.
An atom with more electrons than protons becomes negatively charged, forming an anion. Conversely, if it loses electrons, it becomes positively charged, resulting in a cation.

• Ions play a crucial role in chemistry and biochemistry because they help conduct electricity in solutions and are integral in processes such as nerve signal transmission.
• Not all ions are atomic; complex molecules can form ions too. For instance, sulfate (SO₄²⁻) is an ion that contains multiple atoms.

Recognizing ions and their properties is fundamental in many fields of science and technology.