Question

How many protons, neutrons, and electrons are in the following atoms: (a) \({ }^{40} \mathrm{Ar},(\mathbf{b}){ }^{65} \mathrm{Zn},(\mathbf{c}){ }^{70} \mathrm{Ga},(\mathbf{d}){ }^{80} \mathrm{Br},\) (e) \({ }^{184} \mathrm{~W}\), (f) \({ }^{243} \mathrm{Am} ?\)

Short answer

(a) Argon (\(^{40}\mathrm{Ar}\)): 18 protons, 22 neutrons, and 18 electrons. (b) Zinc (\(^{65}\mathrm{Zn}\)): 30 protons, 35 neutrons, and 30 electrons. (c) Gallium (\(^{70}\mathrm{Ga}\)): 31 protons, 39 neutrons, and 31 electrons. (d) Bromine (\(^{80}\mathrm{Br}\)): 35 protons, 45 neutrons, and 35 electrons. (e) Tungsten (\(^{184}\mathrm{W}\)): 74 protons, 110 neutrons, and 74 electrons. (f) Americium (\(^{243}\mathrm{Am}\)): 95 protons, 148 neutrons, and 95 electrons.

Step-by-step solution

(a) Finding protons, neutrons, and electrons for Argon (Ar)

Argon is represented as \(^{40}\mathrm{Ar}\). The atomic mass number (A) is 40, and the atomic number (Z) of Argon is 18 (you can find it on the periodic table). Using these values: - Number of protons (Z) = 18 - Number of neutrons (A - Z) = 40 - 18 = 22 - Number of electrons = 18 (since it's a neutral atom)

(b) Finding protons, neutrons, and electrons for Zinc (Zn)

Zinc is represented as \(^{65}\mathrm{Zn}\). The atomic mass number (A) is 65, and the atomic number (Z) of Zinc is 30. Using these values: - Number of protons (Z) = 30 - Number of neutrons (A - Z) = 65 - 30 = 35 - Number of electrons = 30

(c) Finding protons, neutrons, and electrons for Gallium (Ga)

Gallium is represented as \(^{70}\mathrm{Ga}\). The atomic mass number (A) is 70, and the atomic number (Z) of Gallium is 31. Using these values: - Number of protons (Z) = 31 - Number of neutrons (A - Z) = 70 - 31 = 39 - Number of electrons = 31

(d) Finding protons, neutrons, and electrons for Bromine (Br)

Bromine is represented as \(^{80}\mathrm{Br}\). The atomic mass number (A) is 80, and the atomic number (Z) of Bromine is 35. Using these values: - Number of protons (Z) = 35 - Number of neutrons (A - Z) = 80 - 35 = 45 - Number of electrons = 35

(e) Finding protons, neutrons, and electrons for Tungsten (W)

Tungsten is represented as \(^{184}\mathrm{W}\). The atomic mass number (A) is 184, and the atomic number (Z) of Tungsten is 74. Using these values: - Number of protons (Z) = 74 - Number of neutrons (A - Z) = 184 - 74 = 110 - Number of electrons = 74

(f) Finding protons, neutrons, and electrons for Americium (Am)

Americium is represented as \(^{243}\mathrm{Am}\). The atomic mass number (A) is 243, and the atomic number (Z) of Americium is 95. Using these values: - Number of protons (Z) = 95 - Number of neutrons (A - Z) = 243 - 95 = 148 - Number of electrons = 95

Key concepts

Protons

Protons are the positively charged particles found in the nucleus of an atom. Think of the nucleus as the core part of the atom, where it holds most of the atom's mass. The number of protons, also called the atomic number (Z), essentially defines the identity of an element. Each element on the periodic table has a unique atomic number.

In neutral atoms, the number of protons is equal to the number of electrons, which balances out the charges. Elements like Argon, Zinc, and Gallium have atomic numbers of 18, 30, and 31 respectively, meaning they contain 18, 30, and 31 protons in their nuclei. This is critical because the number of protons determines the chemical properties and abilities of an atom to engage in chemical reactions. Without a specific number of protons, we wouldn’t be able to differentiate one element from another!

Neutrons

Neutrons are neutral particles, meaning they have no charge. They are also located in the atom's nucleus, alongside the protons. While protons decide the element type, neutrons help add mass and influence the isotope form of the element.

The atomic mass number (A) is the total number of protons and neutrons within the nucleus of an atom. To find the number of neutrons in an atom, we subtract the atomic number from the atomic mass number:

• For Argon \(A = 40\), its neutrons = \(40 - 18 = 22\).
• For Gallium \(A = 70\), its neutrons = \(70 - 31 = 39\).
• For Tungsten \(A = 184\), its neutrons = \(184 - 74 = 110\).

Isotopes are different forms of the same element, varying only in the number of neutrons they possess. Knowing how many neutrons are in an atom is particularly useful for understanding these isotope varieties.

Electrons

Electrons are subatomic particles with a negative charge. They are found in electron shells or orbitals surrounding the nucleus. This is very different from protons and neutrons which stay in the nucleus. Surrounding the nucleus and contributing to the atom's volume more than its mass, electrons play a key role in chemical bonding and reactions.

In atoms, electrons equal the number of protons for a neutral state, providing balance between positive and negative charges. Taking Zinc as an example, with 30 protons, there are also 30 electrons circling it.

• These electrons move rapidly and are arranged in layers called energy levels or shells.
• Each shell can hold a certain number of electrons, with the innermost level filling first.
• The arrangement of electrons determines how an atom will interact with other atoms.

In summary, electrons are essential for forming bonds between atoms, leading to the creation of molecules and compounds that make up the matter around us.