Atomic Glow Slides
Atomic Glow
Flame Test Spectroscopy Lab
Chemistry 101
Unit: Atomic Structure
Today's Objectives
01 Observation
Observe and record the characteristic flame colors produced by different metal ions.
02 Identification
Use your data to identify a "Mystery Sample" based on its unique spectral signature.
03 The Bohr Model
Explain the relationship between electron excitation, relaxation, and photon emission.
Safety Protocol
Eye Protection
Goggles must be worn at ALL times. No exceptions, even when writing.
Bunsen Burner Control
Tie back long hair. Never leave a flame unattended. Clear all flammable paper from the bench.
Chemical Toxicity
Wash hands thoroughly after the lab. Do not touch salts with bare skin.
Why the color?
E = hf
1. Ground State
Electrons orbit the nucleus in stable, low-energy levels.
2. Excitation
Heat energy pushes electrons to a higher energy shell.
3. Relaxation & Emission
The electron drops back down, releasing energy as a photon of specific light.
Heat In
Photon Out
Step-by-Step Procedure
1
Adjust your Bunsen burner to a hot, blue flame with a visible inner cone.
2
Dip the clean wire loop into distilled water, then into the metal salt crystal.
3
Place the loop in the hottest part of the flame (tip of the inner cone).
4
Observe the first color change and record it in your data table.
The Final Challenge
Once you have tested all known samples, come to the teacher's bench to test Mystery Sample X.
Can you match the glow to the correct element?
Atomic Glow Lab Guide
Atomic Glow
Flame Test Spectroscopy Investigation
Name:
Date:
Introduction
When elements are heated in a flame, their electrons absorb energy and jump to higher energy levels (excited state). As these electrons quickly return to their original levels (ground state), they release the excess energy in the form of light. Because each element has a unique arrangement of electrons and energy levels, each element produces a unique "spectral fingerprint" of light. In this lab, you will identify metal ions based on the specific colors they emit.
Safety Warnings
- Goggles must be worn at all times.
- Bunsen burners are hot; keep hair and sleeves back.
- Treat all metal salts as toxic. Wash hands.
- Dispose of chemicals in the designated waste jar.
Materials
- • Bunsen Burner
- • Nichrome wire loop
- • Distilled water
- • 6M HCl (Cleaning)
- • Metal Salt Samples
- • Cobalt Blue Glass
Pre-Lab Questions
1. Define "Excited State" vs "Ground State" in terms of electron position.
2. Is the light produced when an electron moves to a higher level or back to a lower level?
Observation Data
Record specific hues (e.g., "Crimson" vs "Orange-Red")
| Metal Ion | Formula | Flame Color Observed |
|---|
| Lithium | LiCl | |
| Sodium | NaCl | |
| Potassium | KCl | |
| Calcium | CaCl2 | |
| Strontium | SrCl2 | |
| Barium | BaCl2 | |
| Copper | CuCl2 | |
| MYSTERY X | ??? | |
Analysis & Conclusions
1. Based on your data, identify Mystery Sample X and explain your reasoning.
2. Why is it important to clean the nichrome wire in HCl between each test?
3. If two different elements emitted a green light, how could you distinguish between them without using a flame test?
Atomic Glow Teacher Guide
Teacher Facilitation Guide
Atomic Glow
Setup, Keys, & Troubleshooting
Lab Preparation
Chemical Solutions (Recommended)
Using 0.5M aqueous solutions of chloride salts provides the cleanest results.
- Lithium Chloride (LiCl) 21.2 g/L
- Sodium Chloride (NaCl) 29.2 g/L
- Potassium Chloride (KCl) 37.3 g/L
- Calcium Chloride (CaCl2) 55.5 g/L
- Strontium Chloride (SrCl2) 79.3 g/L
- Barium Chloride (BaCl2) 104.1 g/L
- Copper(II) Chloride (CuCl2) 67.2 g/L
Equipment Stations
- • 8 Bunsen burners + strikers
- • 8 Nichrome wire loops (pre-cleaned)
- • 16 Small beakers (50mL) for salts & HCl
- • Wash bottles with distilled water
- • Cobalt blue glass (for K+ test)
- • Waste container for heavy metals (Ba, Cu, Sr)
Expected Spectral Data
| Metal Ion | Dominant Color | Notes/Hues |
|---|
| Lithium (Li+) | Crimson / Red | Deep, rich red. Long duration. |
| Sodium (Na+) | Intense Yellow | Very bright; can mask other colors. |
| Potassium (K+) | Lilac / Light Purple | Faint. Use Cobalt Glass to filter Na+ yellow. |
| Calcium (Ca2+) | Orange-Red | Brick red hue. |
| Strontium (Sr2+) | Scarlet | Brighter red than Calcium. |
| Barium (Ba2+) | Pale Green / Yellow-Green | Faint "apple green" color. |
| Copper (Cu2+) | Blue-Green | Very distinct and vibrant. |
Answer Key & Analysis
Pre-Lab Analysis
1. Excited vs Ground: Ground state is the lowest energy orbital an electron normally occupies. Excited state is a higher energy orbital occupied when the electron absorbs energy.
2. Light Production: Light is produced when an electron moves back to a lower level (relaxation), releasing a photon.
Post-Lab Analysis
1. Mystery Sample: Answers vary. Recommended: Use Strontium (Scarlet) or Copper (Blue-Green) as they are the most distinct.
2. HCl Cleaning: To remove any residual metal ions from the previous test. Sodium is a common contaminant that easily masks other colors with its bright yellow glow.
