This document discusses writing chemical formulas for covalent substances like H2O, O2, H2, and CO2. It explains that formulas are written by counting the number of atoms of each element, and uses the example of PH3 to show how phosphorus bonds with 3 hydrogen atoms due to its 3 unpaired electrons.

1. Formulae for covalent substances
By Kunal

2. Showing Covalent Bonds
H2O
O2
H2
CO2

3. For writing a formula, we need to count the
number of atoms required from each element.

4. PH3 Formula

5. The phosphorous initially had 3 unpaired
electrons.
So, 3 hydrogen atoms bonded with it.
The formula is PH3.

6. Thankyou