Elements, Compounds, and Chemical Formulas Review

Which of the following best defines an element?

• A pure substance that cannot be broken down into simpler substances by a chemical reaction.

• A mixture of two or more substances.

• A chemical combination of two or more elements.

• A number that represents the number of molecules present.

Tags

NGSS.MS-PS1-1

What is a compound?

• A pure substance made of only one type of atom.

• A chemical combination of two or more elements.

• Two or more atoms physically mixed together.

• The number before a compound formula.

Tags

NGSS.MS-PS1-1

Which of the following is the best description of a molecule?

• A single atom of an element.

• Two or more atoms chemically combined.

• A mixture of compounds.

• The number before a chemical formula.

Tags

NGSS.MS-PS1-1

What does the coefficient in a chemical formula represent?

• The type of atoms in the molecule.

• The number of atoms in a molecule.

• The number of molecules that are present.

• The total mass of the compound.

Given the chemical equation 2H₂ + O₂ → 2H₂O, how many molecules of water are produced, and what does the coefficient "2" in front of H₂O indicate? (DoK Level 3: Strategic Thinking)

• 2 molecules of water are produced; the coefficient "2" means there are 2 molecules of water.

• 1 molecule of water is produced; the coefficient "2" means there are 2 atoms of hydrogen.

• 2 molecules of oxygen are produced; the coefficient "2" means there are 2 atoms of oxygen.

• 4 molecules of water are produced; the coefficient "2" means there are 4 molecules of water.

Tags

NGSS.MS-PS1-5

What does the subscript in a chemical formula represent?

• The number of molecules in the reaction

• The number of atoms of an element in a compound

• The total mass of the compound

• The charge of the element

Tags

NGSS.MS-PS1-1

Which of the following best describes an element symbol?

• A picture of the element

• The full name of the element

• A one or two letter representation of an element

• The atomic mass of the element

What does the term "diatomic" refer to?

• Two different elements bonded together

• Two atoms of the same element bonded together

• A single atom

• Three atoms bonded together

Tags

NGSS.MS-PS1-1

Explain how you can determine the number of atoms of each element in the compound H₂O using the chemical formula.

• By counting the letters in the formula

• By looking at the subscript numbers next to each element symbol

• By adding the atomic numbers of each element

• By checking the color of the element symbol

Tags

NGSS.MS-PS1-1

Which type of chemical bond is formed when two atoms share one or more pairs of electrons to achieve a stable outer electron shell?

• Covalent bond

• Ionic bond

• Metallic bond

• Hydrogen bond

Tags

NGSS.HS-PS1-1