Question

The following table gives numbers of electrons, protons, and neutrons in atoms or ions of a number of elements. Answer the following: (a) Which of the species are neutral? (b) Which are negatively charged? (c) Which are positively charged? (d) What are the conventional symbols for all the species? \begin{tabular}{lccccccc} & \multicolumn{5}{c} { Atom or Ion of Element } \\ \cline { 2 - 8 } & A & B & C & D & E & F & G \\ \hline Number of electrons & 5 & 10 & 18 & 28 & 36 & 5 & 9 \\ Number of protons & 5 & 7 & 19 & 30 & 35 & 5 & 9 \\ Number of neutrons & 5 & 7 & 20 & 36 & 46 & 6 & 10 \\ \hline \end{tabular}

Short answer

(a) A, F, G are neutral. (b) B, E are negatively charged. (c) C, D are positively charged. (d) \( {}^{10}_{5}\text{B}, {}^{14}_{7}\text{N}^{3-}, {}^{39}_{19}\text{K}^{+}, {}^{66}_{30}\text{Zn}^{2+}, {}^{81}_{35}\text{Br}^{-}, {}^{19}_{9}\text{F} \)

Step-by-step solution

Identify Neutral Species

An atom or ion is neutral if the number of electrons is equal to the number of protons. Compare the numbers of electrons and protons in each column. - A: Electrons = 5, Protons = 5 (Neutral) - B: Electrons = 10, Protons = 7 (Not Neutral) - C: Electrons = 18, Protons = 19 (Not Neutral) - D: Electrons = 28, Protons = 30 (Not Neutral) - E: Electrons = 36, Protons = 35 (Not Neutral) - F: Electrons = 5, Protons = 5 (Neutral) - G: Electrons = 9, Protons = 9 (Neutral) Species A, F, and G are neutral.

Identify Negatively Charged Species

An ion is negatively charged (anion) when it has more electrons than protons. Check for this condition in the table: - A: Electrons = 5, Protons = 5 (Neutral) - B: Electrons = 10, Protons = 7 (Negatively charged) - C: Electrons = 18, Protons = 19 (Not negatively charged) - D: Electrons = 28, Protons = 30 (Not negatively charged) - E: Electrons = 36, Protons = 35 (Negatively charged) - F: Electrons = 5, Protons = 5 (Neutral) - G: Electrons = 9, Protons = 9 (Neutral) Species B and E are negatively charged.

Identify Positively Charged Species

An ion is positively charged (cation) when it has fewer electrons than protons. - A: Electrons = 5, Protons = 5 (Neutral) - B: Electrons = 10, Protons = 7 (Negatively charged) - C: Electrons = 18, Protons = 19 (Positively charged) - D: Electrons = 28, Protons = 30 (Positively charged) - E: Electrons = 36, Protons = 35 (Negatively charged) - F: Electrons = 5, Protons = 5 (Neutral) - G: Electrons = 9, Protons = 9 (Neutral) Species C and D are positively charged.

Assign Conventional Symbols

Conventional symbols are represented using the element symbol with mass number (protons + neutrons) as a superscript on the left and charge as a superscript on the right.- A & F (Neutral Boron): \[ {}^{10}_{5} ext{B} \]- B (Negatively charged, Nitrogen): \[ {}^{14}_{7} ext{N}^{3-} \]- C (Positively charged, Argon deprived): \[ {}^{39}_{19} ext{K}^{+} \]- D (Positively charged, Zinc deprived): \[ {}^{66}_{30} ext{Zn}^{2+} \]- E (Negatively charged, Bromine): \[ {}^{81}_{35} ext{Br}^{-} \]- G (Neutral Fluorine): \[ {}^{19}_{9} ext{F} \]

Key concepts

Neutral Atoms

A neutral atom is a fundamental concept in chemistry and atomic structure. This concept is based on an atom having an equal number of protons and electrons. Because protons carry a positive charge and electrons carry a negative charge, these charges cancel each other out in a neutral atom, resulting in no overall charge.

For example, in the exercise given, species A, F, and G were identified as neutral. Here’s why:

• Species A: 5 electrons and 5 protons.
• Species F: 5 electrons and 5 protons.
• Species G: 9 electrons and 9 protons.

Given that there is an equal number of protons and electrons in these species, they exhibit no net charge. Neutral atoms are a key building block in understanding how different atoms interact with each other in chemical reactions.

Ions

Ions are formed when an atom or group of atoms gains or loses electrons, resulting in a net charge. When electrons are added or removed, they either create negatively charged ions called anions or positively charged ions known as cations.

• Anion: Occurs when there are more electrons than protons.
• Cation: Occurs when there are fewer electrons than protons.

In our exercise, species B and E are examples of anions because they have more electrons than protons. Conversely, species C and D are examples of cations because they have fewer electrons than protons.

Understanding ions is crucial as they play key roles in chemical reactions, balancing charges and creating ionic bonds in compounds. Ions are also essential in many biological and technological processes.

Electrons

Electrons are subatomic particles with a negative electrical charge, found in electron clouds surrounding the nucleus of an atom. They are much lighter than protons and neutrons, which reside in the nucleus.

Electrons play a vital role in determining the chemical properties of an element. The number of electrons in an atom influences how it interacts with other atoms.

In atomic physics, the electrons contribute significantly to the atom's volume, though not much to its mass. In the exercise, fluctuating numbers of electrons in each atom or ion were key to determining whether the entity was neutral or an ion. Understanding electrons helps illustrate how atoms bond and react, forming different materials and molecules.

Protons

Protons are positively charged particles found in the nucleus of an atom. They are composed of three quarks held together by strong forces. Protons, along with neutrons, determine the atomic mass of an element.

The number of protons defines the element itself; for example, all atoms with one proton are hydrogen atoms. This is known as the atomic number. In our exercise, the number of protons in each species helped identify the element's identity and distinguish between neutral atoms and ions based on their charge.

Protons' positive charge is balanced by electrons' negative charge in neutral atoms, while in ions, this balance is disrupted. Understanding protons helps explain the stability, identity, and chemical behavior of elements.

Neutrons

Neutrons are neutral subatomic particles found in the nucleus of an atom alongside protons. They have no electric charge and a similar mass to protons. Neutrons play a pivotal role in the stability of an atom.

The number of neutrons can vary in atoms of the same element, leading to different isotopes. However, this variation doesn't affect the chemical properties significantly.

In our exercise, even though species had different numbers of neutrons, this variation primarily influences the mass and stability rather than their charge balance.

Neutrons help bind protons in the nucleus, counteracting the repulsive forces between the positively charged protons, thus contributing to the atom's structural integrity.