2.3 Water Chemistry

Pure water is made of how many hydrogen (H) atoms and how many oxygen (O) atoms?

• 2 hydrogen (H) atoms and 1 oxygen (O) atom

• 1 hydrogen (H) atom and 2 oxygen (O) atoms

• 2 hydrogen (H) atoms and 2 oxygen (O) atoms

• 1 hydrogen (H) atom and 1 oxygen (O) atom

What is the chemical formula for a single molecule of water?

• H2O

• CO2

• O2

• H2O2

Molecules like water stay together because the ______ are bonded.

• atoms

• electrons

• molecules

• protons

Covalent bonds mean atoms are sharing ______, the negatively charged particle in an atom.

• protons

• neutrons

• electrons

• molecules

Hydrogen (H) has a single electron.

• True

• False

Pure water is made of how many hydrogen (H) atoms and how many oxygen (O) atoms?

• 1 hydrogen and 2 oxygen

• 2 hydrogen and 1 oxygen

• 2 hydrogen and 2 oxygen

• 1 hydrogen and 1 oxygen

What is the chemical formula for a single molecule of water?

• H2O

• H2O2

• CO2

• O2

pH, a measure of acidity, is based on the number of free ________ (H) or ________ (OH) molecules in a substance.

• hydrogen, hydroxide

• oxygen, nitrogen

• carbon, sulfur

• sodium, chloride

Free hydrogen atoms or oxygen bonded with only one hydrogen (called hydroxide) can change pH.

• True

• False

A charge (such as + or -) on an atom or molecule indicates:

• an imbalance in the number of protons and electrons

• the presence of extra neutrons

• the atom is radioactive

• the atom is in a gaseous state