Question

What species is represented by the following information?

p⁺ = 17 n° = 18 e⁻ = 18

A) Cl
B) Cl⁻
C) Ar
D) Ar⁺
E) Kr

Answer 1

The species represented by the given information is determined by the number of protons (p⁺), neutrons (n°), and electrons (e⁻) it has:

Protons (p⁺) = 17

Neutrons (n°) = 18

Electrons (e⁻) = 18

The atomic number of an element is defined by its number of protons. Therefore, with 17 protons, the element is chlorine (Cl), as chlorine has an atomic number of 17.

However, we also need to consider the number of electrons to determine if it's a neutral atom or an ion:

Neutral Chlorine Atom: Would have 17 electrons (equal to its atomic number).

Chloride Ion (Cl⁻): Would have 18 electrons, one more than its atomic number, making it a negatively charged ion.

Given that this species has 18 electrons, it is a chloride ion (Cl⁻). Thus, the correct answer is:

B) Cl⁻

Answer 2

Let's break down this question in a way that's easy to understand:

You're given the following information about a certain species:

Protons (p⁺) = 17

Neutrons (n°) = 18

Electrons (e⁻) = 18

Let's go through these step-by-step:

1. Protons (p⁺) = 17: The number of protons in an atom tells us which element it is. Every element in the periodic table has a unique number of protons. For example, hydrogen has 1 proton, helium has 2, and so on. In this case, we have 17 protons. If you look at the periodic table, the element with 17 protons is chlorine, which is symbolized as Cl.

2. Neutrons (n°) = 18: Neutrons are particles in an atom's nucleus that have no charge. They're important for the stability of the atom, but they don't change what element it is. So, knowing we have 18 neutrons is useful for some things, but it doesn't change that we're dealing with chlorine.

3. Electrons (e⁻) = 18: Electrons are tiny particles that orbit the nucleus of an atom. They have a negative charge. The number of electrons usually equals the number of protons in a neutral atom. So, a neutral chlorine atom would have 17 electrons. But here, we have 18 electrons, which is one more than the number of protons. This extra electron gives the atom a negative charge, making it an ion (specifically, a negatively charged ion).

So, putting it all together:

• We have a chlorine atom (because of the 17 protons).
• It has an extra electron (18 instead of 17), which makes it a negatively charged ion.
• A negatively charged ion is written with a minus sign (−). So, we call it chloride ion, written as Cl⁻.

Therefore, the answer is Cl⁻, which is option B.

Let's look at why the other options are not correct:

A) Cl (Chlorine): This would be a neutral chlorine atom. A neutral atom has the same number of protons and electrons. Since chlorine has 17 protons, a neutral chlorine atom would also have 17 electrons. In our case, the species has 18 electrons, which is one more than its number of protons, making it an ion, not a neutral atom.

C) Ar (Argon): Argon is another element on the periodic table. It has 18 protons. Remember, the number of protons defines the element. Since our species has only 17 protons, it cannot be argon.

D) Ar⁺ (Argon Ion): This represents an argon atom that has lost an electron, making it a positively charged ion. First, argon has 18 protons, not 17, so our species can't be argon. Secondly, since our species has more electrons than protons, it would be negatively charged (if it were an ion of argon), not positively charged.

E) Kr (Krypton): Krypton is another element, which has 36 protons. This is far more than the 17 protons our species has, so it can't be krypton.

So, the correct answer is Cl⁻ (option B) because our species matches chlorine in terms of its proton number (17) but has an extra electron, making it a negatively charged ion, not a neutral atom or another element.