4. What happens when atoms combine to form a compound? Explain with an example.s. Write the differences between monoatomic ions and polyatomic ions with the help of example6. Describe the periodic table.

4. What happens when atoms combine to form a compound? Explain with an

1.	4. What happens when atoms combine to form a compound? Explain with an example.s. Write the differences between monoatomic ions and polyatomic ions with the help of example6. Describe the periodic table.
Answer» <p>4. When elements react, their atoms join with other atoms to form compounds. Chemical bonds form, which involves atoms transferring or sharing electrons.</p> <p>5. A monatomic ion consists of a single atom that is ionized. For example Na+, Cl-, Fe+3, O-2. A polyatomic ion consists of several atoms bonded to each other, but acting as if it were one ion. ClO3-, NH3+, SO4-2, CO3-2.</p> <p>6. The periodic table is a tabular arrangement of the chemical elements, ordered by their atomic number, electron configuration, and recurring chemical properties, whose structure shows periodic trends. The modern periodic table consists of 7 horizontal periods and 16 vertical groups ( 18 vertical columns ) . The elements of the modern periodic table are classified into 4 blocks.</p>