3A - CHEMICAL FORMULA Essential Chemistry Investigations

[Pages:2]3A ? CHEMICAL FORMULA

How can you represent the elements in a compound?

? Molecular Model Set

? Periodic table

STUDENT HANDOUT

Chemical formulas are used to represent pure substances. In this investigation, different atoms are represented by different colored balls. The sticks in the model set represent the bonds that hold the atoms together. A structural diagram can be used to indicate the arrangement of the atoms in a compound.

Follow regular lab safety procedures.

Part 1 - Simple molecules

Use the Molecular Model Set "Contents" card to match each element with each color in the following table. Use your periodic table to determine the element's symbol, atomic number, group and period. Record all answers in the matching table on your answer sheet.

Color Key for Molecular Model Set and Element Information

Color Element Black Carbon

Element symbol

Atomic number

Group

White Hydrogen

Red Oxygen

Blue Nitrogen

Orange Phosphorus

Yellow Sulfur

Green Chlorine

Purple Sodium

Period

PASCO / EC-6352

1

3A ? CHEMICAL FORMULA / STUDENT HANDOUT

Pick 5 atoms and connect them with bonds to form a compound. At least 2 of the atoms must be the same color and at least two atoms must be different colors. Draw a diagram of your compound in Table 1 on your answer sheet and determine its chemical formula. Build the following stable simple molecules: H2O, CH4, NH3, CCl4. Draw the structural formula in Table 2 on your answer sheet.

Complete the analysis for Part 1 on your answer sheet.

Part 2 ? Atom arrangement

Build the following models with the following numbers of atoms. Draw the structural diagram and write the chemical formula in Table 3 on your answer sheet. Make sure all atoms have the appropriate numbers of bonds.

Model A B C

Carbon 3 3 2

Models to build

Hydrogen 8 8 7

Oxygen 0 1 0

Nitrogen 0 0 1

Complete the analysis for Part 2 on your answer sheet.

Answer the questions on your answer sheet.

2 PASCO / EC-6352

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