Science 8: Ch 9.2 Chemical Formulas and Equations (Pages 262-267)

Name:______date:______period:______(3)

Science 8: Ch 9.2 Chemical Formulas and Equations (pages 262-267)

Key Concept
Chemical formulas and chemical equations are used to ______how atoms are ______to form new substances in a ______.
In the analogy letters are used to form words, how are chemical symbols are put together to make what?
Chemical formulas added together to describe what?
All substances are formed by about how many elements?
Define chemical formula
What does a chemical formula show?
What is the chemical formula for water?
How many atoms of hydrogen are in one molecule of water?
How many atoms of oxygen are in one molecule of water?
What is a subscript?
If an atom in a chemical formula has no subscript, what does that mean?
Simple covalent compounds are usually composed of what?

Record the data in TABLE 1 page 263

Prefixes used in ______

=1 / =6
=2 / =7
=3 / =8
=4 / =9
=5 / =10
Are carbon and oxygen metals or nonmetals?
Use the proper prefixes to write out CO2.
Use the proper prefixes to write out N2O.
If a compound contains a metal and a nonmetal, what type of a compound is it?
When writing a formula for an ionic compound, you first have to have sure it has what type of charge?
How many valence electrons from Na have?
What is the charge on Na?
How many electrons does Cl have?
What is the charge in Cl?
Does NaCl have a 0 charge?
What is the charge on Mg?
How many electrons does Mg have?
What is the charge in Cl?
Does MgCl have a 0 charge?
How can you make MgCl have a 0 charge?
Define chemical equation.
Define reactant
What are the reactants in Figure 5 on page 264?
Define product
What is the product in Figure 5?
What does the + sign represent in a chemical equation?
Which direction does the arrow point in a chemical reaction?
If an equation has the wrong chemical symbol or formula, what will it not describe?

Looking at Figure 6 on page 265, what is the difference between:

CoCOCO2

Are atoms lost or gained in a chemical reaction?
What do atoms do in a chemical reaction?
Every atom in the reactants becomes part of what?
To balance an equation, what do you need to check?
What is the law of conservation of mass?
Whose work helped in the making of the law of conservation of mass?
What can we say about the mass of the reactants and the products in a chemical reaction?
What is a coefficient?
What does 2CO represent?
What is the coefficient in 2CO?
If 2H2O has four atoms of hydrogen, how did you get the four atoms?
What is changed when balancing an equation, coefficients or subscripts?
If a subscript is changed in a formula for a compound, what changes?

Using Figure 7 on page 266, complete the following:

1) Write the balanced equation for water using chemical formulas.

2) Record the steps to balance the equation for water.