Question

Write the atomic symbol for each of the following: a. an atom with 4 protons and 5 neutrons b. an atom with 12 protons and 14 neutrons c. a calcium atom with a mass number of 46 d. an atom with 30 electrons and 40 neutrons e. a copper atom with 34 neutrons

Short answer

(a) \(_4^9\text{Be}\), (b) \(_{12}^{26}\text{Mg}\), (c) \(_{20}^{46}\text{Ca}\), (d) \(_{30}^{70}\text{Zn}\), (e) \(_{29}^{63}\text{Cu}\).

Step-by-step solution

- Understanding Atomic Notation

The atomic symbol for an element consists of its chemical symbol, the atomic number (number of protons), and the mass number (sum of protons and neutrons). It can be represented as \text :\(_Z^A\text{X}\), where \text{X} is the chemical symbol, \text{Z} is the atomic number, and \text{A} is the mass number.

- Atom with 4 Protons and 5 Neutrons

The element with 4 protons is Beryllium (\text{Be}). The atomic number \text{Z} is 4, and the mass number \text{A} is the sum of protons and neutrons: 4 + 5 = 9. Therefore, the atomic symbol is \(_4^9\text{Be}\).

- Atom with 12 Protons and 14 Neutrons

The element with 12 protons is Magnesium (\text{Mg}). The atomic number \text{Z} is 12, and the mass number \text{A} is 12 + 14 = 26. Therefore, the atomic symbol is \(_{12}^{26}\text{Mg}\).

- Calcium Atom with a Mass Number of 46

The element Calcium (\text{Ca}) has an atomic number of 20. The mass number is given as 46. Therefore, the atomic symbol is \(_{20}^{46}\text{Ca}\).

- Atom with 30 Electrons and 40 Neutrons

An atom with 30 electrons typically has 30 protons (assuming it is neutral). This element is Zinc (\text{Zn}). The atomic number \text{Z} is 30, and the mass number \text{A} is 30 + 40 = 70. Therefore, the atomic symbol is \(_{30}^{70}\text{Zn}\).

- Copper Atom with 34 Neutrons

The element Copper (\text{Cu}) has an atomic number of 29. The mass number \text{A} is 29 + 34 = 63. Therefore, the atomic symbol is \(_{29}^{63}\text{Cu}\).

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. This number is crucial because it defines the element itself. For example, the atomic number of Hydrogen is 1, meaning every hydrogen atom has 1 proton.
An important point to remember is that in a neutral atom, the atomic number also equals the number of electrons.
This balance keeps the atom electrically neutral, as protons have a positive charge and electrons have a negative charge.

Mass Number

The mass number is the total number of protons and neutrons in an atom's nucleus. It is represented by the symbol \(A\). The mass number is an integer and is always larger than or equal to the atomic number.
For instance, if an atom has 12 protons and 14 neutrons, its mass number will be 12 + 14 = 26.
Knowing the mass number is essential when writing atomic symbols as it helps distinguish between different isotopes of the same element, which have the same number of protons but different numbers of neutrons.

Protons

Protons are subatomic particles found in the nucleus of an atom. They carry a positive charge and their number defines the element. Each proton contributes a +1 charge to the atom.
For example, every carbon atom has 6 protons, which makes its atomic number 6. The number of protons is crucial in determining the element's identity and its position in the periodic table.
A higher number of protons generally indicates a heavier and more complex element.

Neutrons

Neutrons are neutral subatomic particles located in the nucleus of an atom. Unlike protons, they do not carry any charge, but they do contribute to the mass of the atom.
Neutrons play a critical role in the stability of an atom. Even though they don't affect the chemical properties directly (which depend more on protons and electrons), they provide the necessary 'glue' that holds the atomic nucleus together, especially in larger atoms.
The number of neutrons can vary even among atoms of the same element. This variation leads to the formation of isotopes, which are atoms with the same number of protons but different numbers of neutrons.

Element Symbols

Element symbols are shorthand notations for chemical elements. They are usually one or two letters, with the first letter capitalized and the second letter, if present, in lowercase.
For example, the symbol for carbon is \(\text{C}\), and the symbol for magnesium is \(\text{Mg}\). Element symbols are derived from their English names or, sometimes, their Latin names.
Using element symbols makes it easier to write chemical equations and formulas. It is essential to memorize the symbols for common elements, as this will make understanding chemical concepts and notations much more straightforward.