Flame Test & Lab SafetyFlame Test & Lab Safety

ColorsColorsWe can see white light when?We can see white light when?All colored light reaches our eyes at the All colored light reaches our eyes at the same timesame timeOnly a small portion of the electromagnetic Only a small portion of the electromagnetic spectrum is visible by the human eyespectrum is visible by the human eye

Niels BohrNiels Bohr

Modified the planetary model of the atom which had Modified the planetary model of the atom which had electrons orbiting around a nucleus, was very electrons orbiting around a nucleus, was very successful explaining hydrogen’s spectrumsuccessful explaining hydrogen’s spectrumQuantum Hypothesis = a beam of light is not a Quantum Hypothesis = a beam of light is not a continuous train of waves, but is a stream of zillions of continuous train of waves, but is a stream of zillions of particles (photons)particles (photons)Bohr used quanta to explain atomic spectraBohr used quanta to explain atomic spectraAtoms can only emit energy in very precise quantities Atoms can only emit energy in very precise quantities (energy emitted is quantized) and only in precise (energy emitted is quantized) and only in precise steps, electrons occupy specific energy levels. steps, electrons occupy specific energy levels.

LightLightAn atom becomes excited when one of its An atom becomes excited when one of its electrons absorb energy in the form of photons electrons absorb energy in the form of photons (How long does an atom stay excited?)(How long does an atom stay excited?)If enough energy is absorbed then the electron If enough energy is absorbed then the electron can make a quantum leap to the next energy can make a quantum leap to the next energy level, if there is roomlevel, if there is roomWhen the electron returns to a lower energy When the electron returns to a lower energy state the energy is released in the form of a state the energy is released in the form of a photon, which we see as visible lightphoton, which we see as visible lightThe energy of the photon determines its The energy of the photon determines its wavelength or colorwavelength or colorEach element has its own frequencies of color, Each element has its own frequencies of color, so it emits its own distinctive glowso it emits its own distinctive glow

SpectroscopeSpectroscopeAn instrument used to observe the color An instrument used to observe the color components of any light sourcecomponents of any light sourceWhen an element is burned and the flame When an element is burned and the flame looked at with a spectroscope, the color is looked at with a spectroscope, the color is revealed to consist of a pattern of distinct revealed to consist of a pattern of distinct frequenciesfrequenciesList of List of Flame SpectrumFlame SpectrumBelow calcium atomic spectrum (the Below calcium atomic spectrum (the pattern of the frequencies)pattern of the frequencies)

The Flame TestThe Flame TestThe flame test is used to The flame test is used to visually determine the visually determine the identity of an unknown identity of an unknown metal in a compoundmetal in a compoundElements heated by a Elements heated by a flame will glow their flame will glow their characteristic colorcharacteristic colorEg. Fire WorksEg. Fire WorksEg.Sodium headlampsEg.Sodium headlamps

Burning ElementsBurning Elements

Calcium, Lithium, Rubidium, Sodium, PotassiumCalcium, Lithium, Rubidium, Sodium, Potassium

Don’t Let This Happen To YouDon’t Let This Happen To You

Lab SafetyLab Safety

Wear Proper Clothing Wear Proper Clothing • Goggles must be worn at all times while in the Goggles must be worn at all times while in the

laboratory.laboratory.• Appropriate laboratory attire includes clothing Appropriate laboratory attire includes clothing

that covers the torso, arms, legs and feet. that covers the torso, arms, legs and feet. Shorts, short skirts or open-toed shoes are not Shorts, short skirts or open-toed shoes are not appropriate. Loose sleeves should be tied up to appropriate. Loose sleeves should be tied up to prevent them from dropping into a solution or prevent them from dropping into a solution or flame. For the same reason, long hair should be flame. For the same reason, long hair should be tied back.tied back.

Lab SafetyLab SafetyAvoid Chemical ExposureAvoid Chemical Exposure

• No eating, drinking, or chewing gum in the laboratory.No eating, drinking, or chewing gum in the laboratory.• Avoid direct contact with chemicals. Although some reagents are fairly Avoid direct contact with chemicals. Although some reagents are fairly

innocuous, it is always good practice to avoid direct exposure. If you do spill innocuous, it is always good practice to avoid direct exposure. If you do spill something on you, wash it off immediately. ALWAYS wash your hands something on you, wash it off immediately. ALWAYS wash your hands before leaving the laboratory.before leaving the laboratory.

• Avoid touching your hands to your face while in the laboratory. If you Avoid touching your hands to your face while in the laboratory. If you accidentally get chemicals on your hands, you won’t make the mistake of accidentally get chemicals on your hands, you won’t make the mistake of transferring them to your face or eyes.transferring them to your face or eyes.

• Do not sit on the laboratory bench.Do not sit on the laboratory bench.• Do Do NOTNOT smell the vapors given off by a chemical substance unless smell the vapors given off by a chemical substance unless

specifically directed to do so by the instructor. Some vapors, such as specifically directed to do so by the instructor. Some vapors, such as ammonia, can irritate and even damage the lungs if inhaled too strongly. If ammonia, can irritate and even damage the lungs if inhaled too strongly. If detecting the smell of a chemical is indicated, gently waft the chemical detecting the smell of a chemical is indicated, gently waft the chemical vapors towards your nose and carefully inhale. vapors towards your nose and carefully inhale.

• Use fume hoods when carrying out a vigorous reaction or when generating Use fume hoods when carrying out a vigorous reaction or when generating a hazardous gas. Always use the hood when directed to do so.a hazardous gas. Always use the hood when directed to do so.

• Do not pipette by mouth.Do not pipette by mouth.• Never taste a chemical.Never taste a chemical.• Never remove chemicals from the laboratory.Never remove chemicals from the laboratory.

Lab SafetyLab SafetyBunsen Burners Bunsen Burners

• 3 main controls: main gas control (on/off knob on bench; turn on all 3 main controls: main gas control (on/off knob on bench; turn on all the way which is straight down) ; burner gas control (near base of the way which is straight down) ; burner gas control (near base of burner; adjusted with air to give you the proper size flame) ; air burner; adjusted with air to give you the proper size flame) ; air control (barrel of burner) control (barrel of burner)

• When finished, turn off using main control on bench.When finished, turn off using main control on bench.• Open flames (including Bunsen Burners) are not permitted when Open flames (including Bunsen Burners) are not permitted when

flammable substances are present in the laboratory.flammable substances are present in the laboratory.• Exercise caution with long hair and loose clothing around open Exercise caution with long hair and loose clothing around open

flames.flames.

Lab SafetyLab Safety

Use of Safety Equipment Use of Safety Equipment • Eye wash stationsEye wash stations• Safety showerSafety shower• Fire Extinguishers Fire Extinguishers • Emergency ExitsEmergency Exits

Lab SafetyLab SafetyCommon Sense RulesCommon Sense Rules

• Horseplay is not permitted in the laboratory.Horseplay is not permitted in the laboratory.• Bring only a laboratory notebook, pen, and calculator to Bring only a laboratory notebook, pen, and calculator to

your laboratory bench. All other items should be safely your laboratory bench. All other items should be safely stored in the labeled cabinets under the lab bench. stored in the labeled cabinets under the lab bench. Never put anything on the floor as this might cause Never put anything on the floor as this might cause someone to trip or fall or your belongings could be someone to trip or fall or your belongings could be destroyed by spills in the laboratory.destroyed by spills in the laboratory.

• Do not conduct any unauthorized experiments in the Do not conduct any unauthorized experiments in the laboratory.laboratory.

• If unsure about a laboratory procedure, ask the instructor If unsure about a laboratory procedure, ask the instructor for help.for help.

• Never pick up hot objects with your bare hands. Always Never pick up hot objects with your bare hands. Always use the test tube holders and tongs for moving hot use the test tube holders and tongs for moving hot objects. Do not hand hot objects to the instructor.objects. Do not hand hot objects to the instructor.