Pre-Lab 16B: Chemical Formulas

Purpose

Chemists have long noticed that groups of elements behave similarly.

The periodic table is an arrangement of the elements grouped according to similar behavior.

In this investigation, you will discover how the arrangement of electrons in atoms is related to groups on the periodic table.

You will also learn why atoms form chemical bonds with other atoms in certain ratios.

Key Question

• Why do atoms combine in certain ratios?

Background

• Define:

oxidation number

chemical formula

binary compound

Drawing

• Draw this:

Section 3:

1. Using the periodic table on the previous page, determine the ion formed by each element.

2. Figure out how many periodic table tiles of each element will be needed to make the compound electrically neutral.

3. Form the compound with your tiles and write the chemical formula for each compound based on the number of tiles of each element

I SIGN-OFF every other one: SHOW ME THE TILES

4. Add an 8th column to table 1: label it “Chemical Name”

Section 4:

In the 8th column, name the compound you created using these rules:

1. Write the name of the element with a positive oxidation number first

2. Write the root name of the element with a negative oxidation number second. For example, chlor- is the root name of chlorine. Subtract the -ine ending.

3. Add the ending -ide to the root name. Chlor- becomes chloride.

Section 5:

You will now play a crossword puzzle game and try to WIN by scoring the most points:

win by adding up the atomic numbers of the atoms of your compound you create.

• Each person starts w/ ten tiles• KEY POINT: Each turn you must build a compound in

which the oxidation numbers for that compound add up to ZERO (= stable)

• When you use up tiles, pick from the tile bank to restore your # back to ten tiles.

• How do you win?• Read the top of page 91.• I have to SIGN-CHECK YOUR GAME each time you

are done. Complete 2-3 games.

Note changes:

do NOT use the special bond cards

Noble gases:

because they do not bond, you may use them as wild cards

Post Lab 16B: Chemistry Formulas

Purpose

Chemists have long noticed that groups of elements behave similarly.

The periodic table is an arrangement of the elements grouped according to similar behavior.

In this investigation, you will discover how the arrangement of electrons in atoms is related to groups on the periodic table.

You will also learn why atoms form chemical bonds with other atoms in certain ratios.

Key Question

• Why do atoms combine in certain ratios?

Background

• Define:

oxidation number

chemical formula

binary compound

Section 2:

a. How are elements grouped according to the number of valence electrons in their outermost levels?

b. Why do elements in group 2 have an oxidation number of 2+?

c. Why do elements in group 17 have an oxidation number of 1–?

d. Why do the oxidation numbers in the first two groups tend to be positive?

Section 3:Element 1 Element 2 Oxidation # 1 Oxidation # 2 Chemical

Formula

Chemical name

Hydrogen Fluorine

Magnesium Sulfur

Calcium Bromine

Aluminum Oxygen

Potassium Chlorine

Lithium Argon

Rubidium sulfur