Writing the chemical formula of a covalent compound
phosphorus trichloride is used in the production of chemicals that keep plants from growing in a specific area. this
compound is made of one phosphorus atom represented by the chemical symbol p and three chlorine atoms
represented by the chemical symbol cl.
what is the chemical formula of this compound?
pci
pc13
е рзсі
1p3c1
intro
done

PCl₃  

Explanation:

If a molecule contains one P atom and three Cl atoms, its formula must be PCl₃.

A is wrong, because the formula PCl means one atom of P and one of Cl.

C and D are wrong, because the formula P₃Cl indicates a molecule consisting of three P atoms and one Cl atom.

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.