Final answer:
To write Lewis structures for molecules, determine the number of valence electrons and distribute them to form bonds. H₂O has two Hydrogens bonded to Oxygen with two lone pairs. CO₂ has a Carbon double bonded to two Oxygens. NH₃ has three Hydrogens bonded to Nitrogen with one lone pair. CH₄ has four Hydrogens bonded to Carbon.
Step-by-step explanation:
To write Lewis structures for the given molecules, we need to determine the number of valence electrons for each atom in the molecule. Then, we distribute the electrons to form bonds and satisfy the octet rule. Here are the Lewis structures for the given molecules:
a) H₂O: Oxygen has 6 valence electrons and Hydrogen has 1 valence electron. Oxygen forms two bonds with Hydrogen and has two lone pairs of electrons. The structure is H-O-H.
b) CO₂: Carbon has 4 valence electrons and Oxygen has 6 valence electrons. Carbon forms two double bonds with Oxygen, sharing a total of 4 electrons. The structure is O=C=O.
c) NH₃: Nitrogen has 5 valence electrons and Hydrogen has 1 valence electron. Nitrogen forms three bonds with Hydrogen and has one lone pair of electrons. The structure is H-N-H with a lone pair of electrons.
d) CH₄: Carbon has 4 valence electrons and Hydrogen has 1 valence electron. Carbon forms four bonds with Hydrogen. The structure is H-C-H with four Hydrogens around Carbon.