Question

Give the group number and period number for each of the following clements: a. bromine b. argon c. potassium d. radium

Short answer

a. Group 17, Period 4; b. Group 18, Period 3; c. Group 1, Period 4; d. Group 2, Period 7.

Step-by-step solution

- Identify the Position of Bromine in the Periodic Table

Find bromine (Br) on the periodic table. It is located in Group 17 and Period 4.

- Identify the Position of Argon in the Periodic Table

Find argon (Ar) on the periodic table. It is located in Group 18 and Period 3.

- Identify the Position of Potassium in the Periodic Table

Locate potassium (K) on the periodic table. It is in Group 1 and Period 4.

- Identify the Position of Radium in the Periodic Table

Find radium (Ra) on the periodic table. It is found in Group 2 and Period 7.

Key concepts

Group Number

The periodic table is divided into groups, which are the vertical columns. Each group is numbered from 1 to 18. The group number indicates the number of valence electrons found in the outer shell of an element's atoms.
Elements in the same group typically have similar chemical properties. Here is a closer look at the group numbers for the elements in your exercise:

• Bromine (Br): Group 17, known as the halogens.
• Argon (Ar): Group 18, part of the noble gases.
• Potassium (K): Group 1, which contains the alkali metals.
• Radium (Ra): Group 2, belonging to the alkaline earth metals.

Understanding which group an element belongs to can help predict its reactivity and the types of bonds it will form.

Period Number

Periods are the horizontal rows on the periodic table. The period number indicates the highest energy level that contains electrons in an atom of the element. There are seven periods in the modern periodic table.
Let's examine the period numbers for the elements in the exercise:

• Bromine (Br): Period 4, which tells us it has four energy levels.
• Argon (Ar): Period 3, indicating it has three energy levels.
• Potassium (K): Period 4, sharing the same period as bromine, so it has four energy levels.
• Radium (Ra): Period 7, having seven energy levels and placing it in one of the longest rows on the table.

The period number helps determine the electron configuration and chemical behavior of the element.

Element Position

The position of an element in the periodic table is defined by its group and period number. This position can give you a lot of information about the element. For example:

• Bromine (Br): Located in Group 17 and Period 4, bromine is a halogen with important applications in disinfection and flame retardants.
• Argon (Ar): Found in Group 18 and Period 3, argon is a noble gas used in lighting and welding.
• Potassium (K): In Group 1 and Period 4, potassium is an alkali metal essential for biological functions and found in fertilizers.
• Radium (Ra): Existing in Group 2 and Period 7, radium is a radioactive element historically used in luminous paints.

Knowing an element's position helps predict its electron configuration, reactivity, and various practical uses in everyday life.