Chapter 7: Chemical Formulas - Key Questions

A polyatomic ion is:

• an ion made of only one atom

• a neutral molecule

• an ion made of two or more atoms bonded together

• a molecule with no charge

Chemical formulas are used to represent elements.

• True

• False

Identify the names of the elements in NaOH.

• Sodium, Oxygen, Hydrogen

• Nitrogen, Oxygen, Helium

• Sodium, Oxygen, Helium

• Sodium, Nitrogen, Hydrogen

Tags

NGSS.MS-PS1-1

Write the chemical formula for the molecule shown below. The element listed first in the key is written first in the chemical formula. Use your text or the periodic table to help you find symbols of elements you may not know.

• CO₂

• C₂O

• CO

• O₂C

Tags

NGSS.MS-PS1-1

The oxidation numbers of the elements in a compound must always total _____.

• 1

• 0

A subscript following an element in the name of a compound shows the oxidation number of that element in the compound.

• True

• False

What is the formula for the diatomic molecule of Nitrogen (N)?

• N2

• N3

• N4

• NO2

Tags

NGSS.MS-PS1-1

Use the table to find the formula mass of a molecule of each compound listed below. 2. Water (H2O) __________________________

• 18

• 12

• 28

• 44

What is the formula for sodium chloride?

• NaCl.

• NaCO3.

• KCl.

• Na2SO4.

Tags

NGSS.MS-PS1-1

Decide whether the underlined term in each sentence is used correctly. If so, write true in the space provided. If not, change the underlined term to a term in the box. 5. Electrons in the outermost energy level of an atom are called valence electrons.

• true

• protons

• neutrons

• ions

Tags

NGSS.HS-PS1-1