Question

Use the periodic table and the information that follows to write the hyphen notation for each isotope described. a. atomic number = 2, mass number = 4 b. atomic number = 8, mass number = 16 c. atomic number = 19, mass number = 39

Short answer

a. Helium-4 b. Oxygen-16 c. Potassium-39

Step-by-step solution

Understand Hyphen Notation

Hyphen notation for isotopes includes the element name followed by a hyphen and the mass number. The format is: Element-Mass Number.

Identify the Element Using the Atomic Number

Use the periodic table to find the element that corresponds to the given atomic number. The atomic number represents the number of protons in an element.

Hyphen Notation for Part (a)

Find the element with atomic number 2. According to the periodic table, this element is Helium. Hence, the hyphen notation for an isotope with atomic number 2 and mass number 4 is Helium-4.

Hyphen Notation for Part (b)

Find the element with atomic number 8. According to the periodic table, this element is Oxygen. Hence, the hyphen notation for an isotope with atomic number 8 and mass number 16 is Oxygen-16.

Hyphen Notation for Part (c)

Find the element with atomic number 19. According to the periodic table, this element is Potassium. Hence, the hyphen notation for an isotope with atomic number 19 and mass number 39 is Potassium-39.

Key concepts

Atomic Number

The atomic number is a fundamental property of an element that tells us the number of protons in the nucleus of an atom. Each element on the periodic table has a unique atomic number, making it an essential identifier.
For instance, hydrogen has an atomic number of 1 because it has one proton. Similarly, helium has an atomic number of 2, meaning it has two protons.
The atomic number is often denoted as 'Z'.
Knowing the atomic number helps us identify which element we are dealing with in a chemical context.
It's the foundation for other concepts in chemistry, like isotope identification and electron configuration.

Mass Number

The mass number is another crucial property of an element and is defined as the sum of protons and neutrons in the nucleus of an atom. It's denoted using the symbol 'A'.
The mass number is important because while the number of protons defines the element, the number of neutrons can vary, leading to different isotopes.
For example, carbon-12 and carbon-14 are both isotopes of carbon. Carbon-12 has 6 protons and 6 neutrons (mass number = 12), whereas carbon-14 has 6 protons and 8 neutrons (mass number = 14).
Mass number is key in calculating the atomic mass and understanding the isotopic composition of elements.

Periodic Table

The periodic table is an organized chart of elements arranged by increasing atomic number. It helps us quickly identify properties and relationships between different elements.
Each element on the periodic table provides valuable information, such as its atomic number, atomic mass, and symbol.
The table is divided into rows called periods and columns called groups.
Groups contain elements with similar properties, for instance, Group 1 elements are all metals with similar reactivity.
The periodic table is a vital tool in both chemistry and physics for understanding how elements interact and relate to each other.

Element Identification

Identifying an element involves using its atomic number to find it on the periodic table. This process can be understood through a few simple steps:

• First, find the atomic number provided.
• Next, look up this atomic number on the periodic table to determine the element's name and symbol.
• For example, if given the atomic number 8, we locate it on the periodic table and find it corresponds to oxygen.

Once identified, we can use additional information like the mass number to understand which isotope of the element is in question.
By following these steps, we can accurately write the hyphen notation for any isotope using the element name and its mass number.