Parts of a Chemical Equation

Parts of a Chemical Equation

An overview starting with Chemical Symbols and working up to Chemical Formulas

What is a chemical formula?

A chemical formula is a way to represent a chemical reaction through the use of NUMBERS and CHEMICAL SYMBOLS

To understand a chemical formula you must...

• Know how to read the chemical symbols

• know how to read the periodic table

• Know when to multiply numbers

• When to add numbers

Reading Chemical Symbols

To read a chemical symbol, you first, need to know what a chemical symbol is.

A chemical symbol is defined as a single capital letter or one capital and one lower case letter.

This means that when you are reading chemical symbols, if you see two or more capital letters side-by-side, that each capital letter represents a different element.

Multiple Select

Select all of the following examples that contain at least two elements based on the chemical symbols shown:

• H₂+O= H₂O

• C + H₄= CH₄

• O₃+O₂=O₅

• Q₃+Cl₂= 6QCL

To Read a Chemical Formula

You have to make sure you know how to read the Periodic Table of Elements. This table shows you every element that has been discovered so far, and it also shows the chemical symbol for each element.

Reading the numbers...

When looking at a chemical formula, you will see two types of numbers: a coefficient or a subscript.

Open Ended

Can you tell me what a coefficient is?

Coefficients

Are the LARGE NUMBERS located to the left of a chemical symbol.

An important thing to remember is that EVERY SYMBOL behind a coefficient gets multiplied by that coefficient.

Multiple Choice

Which of the following choices shows the correct number of atoms present in molecule 5NaHCO₃?

• 8 atoms

• 15 atoms

• 23 atoms

• 30 atoms

You will multiply to count atoms when

• You see a coefficient

• You see a coefficient and a subscript

• You see parenthesis and then a subscript

• You see a subscript inside the parenthesis and then a subscript outside of the parenthesis

You will add when counting atoms if

• You see the same element listed multiple times in the chemical formula

• 
  

• 
  

• 
  

Open Ended

In your opinion, what is a subscript?

A subscript is the number

To the lower right of the chemical symbol that represents the number of atoms in a single molecule of an atom.

Multiple Choice

How many Aluminum atoms are in Al₂O₃?

• 3

• 2

• 5

Multiple Choice

Al₂

• A single atom

• Elemental Molecule

• Compound Molecule

• None of these

Multiple Choice

Which of the following models best demonstrates a balanced chemical equation?

• F

• G

• H

• J

Multiple Choice

Which of the following chemical equations follows the Law of Conservation of Mass? Hint: which is balanced?

• CO₂ + H₂O --> C₆H₁₂O₆ + O₂

• C₆O + H₁₂O --> C₆H₁₂O₂

• CO₂ + H₂O --> C₆H₁₂O₆ + O₂

• CO₂ +H₂O --> C₆H₁₂O₆ +O₂

Multiple Choice

How many atoms are represented in the reactants of this equation?

• 6

• 12

• 24

• 36

Multiple Choice

2H₂O + 2N → 4H + 2NO

The chemical symbols on the RIGHT (at the end of the equation) are called:

• products

• reactants

• yields/produces

Multiple Choice

In the equation, 2Mg + O₂ ---> 2MgO, which are the reactants?

• 2Mg and O₂

• 2MgO

• Mg and MgO

• O and MgO

Multiple Choice

How many elements are in C₆H₁₂O₆?

• 1

• 2

• 3

• 4

Multiple Choice

Which is the correct formula for:
 three hydrogen (H)
one sulfur (S)
four oxygen (O)

• H₃SO₄
• HSO₄
• H₄S₃O
• H₂O