HELP Fill in the blank.

Atoms are held together in molecules by .
are compounds with the same chemical formula but different molecular structures.
A/An indicates the ratio of atoms in a molecule.
are similar to molecular formulas but show how atoms are bonded together.
When two atoms of the same element combine to form a molecule, this is called a molecule.
The breaking and forming of bonds between atoms in substances results in changes in the contained in the substances.
Respond to the following based on your reading.

Give two purposes for the systematic naming of chemicals.
Name the elements in the molecule H2SO4 and tell how many atoms of each element are present.
How many molecules are represented by 3CO2?