The Flame Test A basic form of Emission Spectroscopy
Ionic Bonding Anions and cations are held together by opposite charges. Anions and cations are held together by opposite charges. Ionic compounds are called salts. Ionic compounds are called salts. Simplest ratio is called the formula unit. Simplest ratio is called the formula unit. The bond is formed through the transfer of electrons. The bond is formed through the transfer of electrons. Electrons are transferred to achieve noble gas configuration. Electrons are transferred to achieve noble gas configuration.
Ionic Bonding NaCl
Ionic Bonding: Lewis Structure Na + Cl -
Ionic Bonding All the electrons must be accounted for! All the electrons must be accounted for! CaP
Ionic Bonding CaP
Ionic Bonding Ca +2 P
Ionic Bonding Ca +2 P Ca
Ionic Bonding Ca +2 P -3 Ca
Ionic Bonding Ca +2 P -3 Ca P
Ionic Bonding Ca +2 P -3 Ca +2 P
Ionic Bonding Ca +2 P -3 Ca +2 P Ca
Ionic Bonding Ca +2 P -3 Ca +2 P Ca
Ionic Bonding Ca +2 P -3 Ca +2 P -3 Ca +2
Ionic Bonding Ca 3 P 2 Formula Unit
Properties of Ionic Compounds Crystalline structure. Crystalline structure. A regular repeating arrangement of ions in the solid. A regular repeating arrangement of ions in the solid. Ions are strongly bonded. Ions are strongly bonded. Structure is rigid. Structure is rigid. High melting points- because of strong forces between ions. High melting points- because of strong forces between ions.
You and Your Partner A test tube rack with 8 test tubes A test tube rack with 8 test tubes Label, by metal, two splints for each test tube Label, by metal, two splints for each test tube Add salt solutions to separate test tube and place labeled splints in appropriate test tube Add salt solutions to separate test tube and place labeled splints in appropriate test tube Soak splints while we review the science behind today’s lab Soak splints while we review the science behind today’s lab Insert wooden splint at tip of inner cone…do not let it burn Insert wooden splint at tip of inner cone…do not let it burn Record color of flame Record color of flame
The Metals Sodium - NaCl Sodium - NaCl Potassium - KCl Potassium - KCl Strontium - Sr(NO 3 ) 2 Strontium - Sr(NO 3 ) 2 Copper - Cu(NO 3 ) 2 Copper - Cu(NO 3 ) 2 Lithium - LiNO 3 Lithium - LiNO 3 Calcium - CaCl 2 Calcium - CaCl 2 Barium - Ba(NO 3 ) 2...caution: POISON Barium - Ba(NO 3 ) 2...caution: POISON Unknown: A, B, C or D Unknown: A, B, C or D
Emission Spectroscopy Technique used to identify unknown elements in a sample Technique used to identify unknown elements in a sample
Basis of Test Electrons in the ground state get excited when energized Electrons in the ground state get excited when energized Excited electrons are unstable Excited electrons are unstable Electrons fall back down to the ground state by releasing energy Electrons fall back down to the ground state by releasing energy Energy takes the form of visible light Energy takes the form of visible light
Line Spectrum Characteristic wavelengths (colors) of light are given off by elements Characteristic wavelengths (colors) of light are given off by elements These wavelengths are an elements line spectrum These wavelengths are an elements line spectrum Hydrogen Hydrogen 410 nm 434 nm 486 nm 656 nm
Flame Test Used to identify metals in solution Used to identify metals in solution Electrons absorb energy from the flame to enter the excited state Electrons absorb energy from the flame to enter the excited state
Safety Goggles and aprons Goggles and aprons Double cone flame Double cone flame Garbage in tin can partially filled with water Garbage in tin can partially filled with water Wash hands and lab station Wash hands and lab station