Atoms and Molecules_G_4

Why is understanding chemical formulas essential?

• To identify elements in molecules

• To calculate molecular weight

• To determine the color of the compound

• To study the physical state of the compound

What type of information do chemical formulas provide?

• Quantities of elements

• Physical properties of elements

• Historical background of elements

• Geographical distribution of elements

What does the formula H₂O indicate?

• A water molecule has 2 hydrogen atoms and 1 oxygen atom.

• A water molecule has 1 hydrogen atom and 2 oxygen atoms.

• A water molecule has 3 hydrogen atoms and 1 oxygen atom.

• A water molecule has 1 hydrogen atom and 1 oxygen atom.

What does the chemical formula H₂O indicate about the composition of water?

• Contains hydrogen and oxygen atoms

• Contains carbon and nitrogen atoms

• Contains sodium and chlorine atoms

• Contains helium and neon atoms

What does O₂ represent in chemical formulas?

• Oxygen molecule with 1 atom

• Oxygen molecule with 2 atoms

• Ozone molecule

• Carbon dioxide molecule

What do chemical formulas represent using symbols and subscripts?

• Elements

• Compounds

• Isotopes

• Ions

What do subscripts indicate in a molecule?

• Number of protons

• Number of neutrons

• Number of atoms of each element

• Number of electrons

What does the subscript in a chemical formula represent?

• Number of electrons in the element
• Number of atoms of that element in the compound
• Number of neutrons in the element
• Number of protons in the element

Which of the following correctly represents the chemical formula for an oxygen molecule?

• O
• O3
• O-
• O2

What information does a chemical formula provide about a molecule?

• Types of elements and numbers of atoms

• Temperature at which the molecule reacts
• Shape of the molecule
• Color of the molecule