Question

Write the atomic symbol for each of the following: a. an aluminum atom with 14 neutrons b. an atom with atomic number 26 and 32 neutrons c. a strontium atom with 50 neutrons d. an atom with a mass number of 72 and atomic number 33

Short answer

a. \( ^{27}_{13}Al \); b. \( ^{58}_{26}Fe \); c. \( ^{88}_{38}Sr \); d. \( ^{72}_{33}As \).

Step-by-step solution

Aluminum Atom with 14 Neutrons

An aluminum atom (Al) has an atomic number of 13, which means it has 13 protons. Given that it has 14 neutrons, the mass number is the sum of protons and neutrons: \(13 + 14 = 27\). Therefore, the atomic symbol is \( ^{27}_{13}Al \).

Atom with Atomic Number 26 and 32 Neutrons

An atom with atomic number 26 is iron (Fe), which means it has 26 protons. Given that it has 32 neutrons, the mass number is the sum of protons and neutrons: \(26 + 32 = 58\). Therefore, the atomic symbol is \( ^{58}_{26}Fe \).

Strontium Atom with 50 Neutrons

A strontium atom (Sr) has an atomic number of 38, which means it has 38 protons. Given that it has 50 neutrons, the mass number is the sum of protons and neutrons: \(38 + 50 = 88\). Therefore, the atomic symbol is \( ^{88}_{38}Sr \).

Atom with Mass Number 72 and Atomic Number 33

An atom with atomic number 33 is arsenic (As), which means it has 33 protons. Given that the mass number is 72, the number of neutrons is the mass number minus the number of protons: \(72 - 33 = 39\). Therefore, the atomic symbol is \( ^{72}_{33}As \).

Key concepts

atomic number

The atomic number of an element is a fundamental property that defines its identity. It tells us the number of protons present in the nucleus of an atom. For example, aluminum has an atomic number of 13, which means every aluminum atom has 13 protons.

This number is crucial because it determines the element's position on the periodic table and its chemical behavior. Here is how it works:

• Atomic number (Z): This is always equal to the number of protons.
• Element identity: Different elements have different atomic numbers.

When you know the atomic number, you can easily identify the element.

mass number

The mass number of an atom is the total number of protons and neutrons in its nucleus. This number is important for understanding the isotope of an element. Isotopes are atoms of the same element with different numbers of neutrons.

For example, in the aluminum atom with 14 neutrons:

• Protons (P): 13
• Neutrons (N): 14
• Mass number (A): P + N = 13 + 14 = 27

The mass number helps in calculating the atomic symbol, which includes both the atomic number and mass number.

neutrons

Neutrons are neutral particles found in the nucleus of an atom. They have no charge but contribute significantly to the mass of the atom. The number of neutrons in an atom can vary, leading to different isotopes of the same element.

For instance, consider the strontium atom with 50 neutrons:

• Total protons (fixed for strontium): 38
• Total neutrons: 50
• Mass number: 38 (protons) + 50 (neutrons) = 88

Knowing the number of neutrons helps in distinguishing between different isotopes.

protons

Protons are positively charged particles located in the nucleus of an atom. The number of protons is equal to the atomic number and defines the element's identity. For instance, iron has 26 protons, and therefore, its atomic number is 26.

Consider an iron atom with 32 neutrons:

• Protons (P): 26
• Neutrons (N): 32
• Mass number (A): P + N = 26 + 32 = 58

Protons determine the chemical properties of the element and its place in the periodic table. They are crucial for understanding the overall structure of the atom.