Elements, Compounds, and Formulae

What is an element?

• A substance that can be broken down into simpler substances by chemical means.

• A substance that cannot be broken down into simpler substances by chemical means.

• A substance that is composed of only one type of atom.

• A substance that can be broken down into simpler substances by physical means.

Give an example of an element.

• hydrogen

• carbon

• nitrogen

• oxygen

How many elements are there in the periodic table?

• 118

• 100

• 92

• 110

What is a compound?

• A compound is a substance formed by the chemical combination of two or more elements in definite proportions.

• A compound is a substance formed by the biological combination of two or more elements.

• A compound is a substance formed by the physical combination of two or more elements.

• A compound is a substance formed by the mechanical combination of two or more elements.

Give an example of a compound.

• Oxygen (O2)

• Nitrogen (N2)

• Water (H2O)

• Carbon dioxide (CO2)

What is the difference between an element and a compound?

• An element is a mixture of different substances, while a compound is a pure substance.

• An element is a pure substance consisting of only one type of atom, while a compound is a substance composed of two or more different elements chemically bonded together.

• An element is a substance that cannot be broken down into simpler substances by chemical means, while a compound is a substance that can be broken down into simpler substances by chemical means.

• An element is a substance composed of two or more different elements chemically bonded together, while a compound is a pure substance consisting of only one type of atom.

What is a chemical formula?

• A chemical formula is a diagram of the atomic structure of a molecule.

• A chemical formula is a list of chemical reactions.

• A chemical formula is a measurement of the concentration of a substance.

• A chemical formula is a representation of a chemical substance using symbols for its constituent elements.

How are chemical formulas written?

• Using colors and shapes to represent elements and their quantities.

• Using words and letters to represent elements and their quantities.

• Using symbols and numbers to represent elements and their quantities.

• Using pictures and diagrams to represent elements and their quantities.

What does the subscript in a chemical formula represent?

• Charge of the atom

• Number of atoms

• Number of electrons

• Mass of the atom

What is the chemical formula for water?

• H2O2

• CO2

• NaCl

• H2O